Current PhD Opportunities

Supervisor

Professor Isobel Hook

Description

In the late 1990s Type Ia supernovae were used as standard candles to discover that the rate of expansion of the universe is accelerating, leading to the idea that some mysterious "dark energy" is pushing the universe apart. Despite much better measurements nowadays, our lack of understanding of dark energy remains one of the most fundamental problems in Physics.

Several new telescopes and surveys are being planned to address this issue. The student will use a combination of archival supernova data, new data from state-of-the-art telescopes and simulated data to study statistical properties of supernovae as distance indicators. Based on these studies, he/she will help to optimise large surveys for cosmology that are planned with future telescopes and instruments, such as the Rubin Observatory, ESA's Euclid mission and 4MOST (the 4meter Multi-Object Spectrograph Telescope). This project will lead up to the start of operation of these exciting telescopes.

Please contact Professor Isobel Hook for further information. This PhD project represents just one component of the research performed by the wider Astrophysics group at Lancaster University. Our PhD projects are offered on a competitive basis and are subject to availability of funding. For more general information about PhD study in Physics at Lancaster please contact our postgraduate admissions staff at py-pgadmiss@lancaster.ac.uk. You can also apply on our PhD page stating the title of the project and the name of the supervisor.

Supervisor

Dr John Stott

Description

Galaxy clusters are the largest gravitationally bound objects in the Universe, consisting of tens to thousands of galaxies within a relatively small volume. They are used extensively as laboratories for galaxy evolution, as they contain galaxies that have experienced a similar environment and processes over many billions of years. They are also key cosmological indicators with the evolution of the number of galaxy clusters of a given mass being very sensitive to the Dark Matter content of the Universe. Because of their importance for both astrophysics and cosmology it is desirable to obtain large, well understood samples of galaxy clusters over a range of redshifts. The Legacy Survey of Space and Time (LSST, https://www.lsst.org/) is an imaging survey performed with the Rubin Observatory that will discover thousands of new galaxy clusters, providing such a sample. It will image the entire southern sky with an 8.4m telescope every few nights for 10 years, producing 200 petabytes of imaging data. This will be the state-of-the-art for optical surveys for many years to come.

This project aims to further develop pre-existing algorithms and machine learning code to identify large numbers of distant galaxy clusters within the LSST survey. These algorithms will be run on existing comparable, but smaller area surveys, and the early-phase of LSST that will begin operation in 2022. The algorithms will be designed so that they can be scaled-up to deal efficiently with the full size of the main LSST survey. The cluster samples generated here will also be used to study the evolution of galaxies in dense environments and potentially cosmology.

Please contact Dr John Stott for further information. This PhD project represents just one component of the research performed by the wider Astrophysics group at Lancaster University. Our PhD projects are offered on a competitive basis and are subject to availability of funding. For more general information about PhD study in Physics at Lancaster please contact our postgraduate admissions staff at py-pgadmiss@lancaster.ac.uk. You can also apply on our PhD page stating the title of the project and the name of the supervisor.

Supervisor

Dr John Stott

Description

As the Universe ages, galaxies find themselves drawn together into filaments, groups and clusters. Galaxies entering these dense environments can experience processes which ultimately lead to a dramatic change in their appearance and internal properties. This project will discover how galaxies are transformed (`quenched’) from blue star-forming spiral discs (like our own Milky Way) into passive red elliptical galaxies, through interactions with their environment.

This PhD project will be a detailed study of galaxy transformation with environment, comparing those in massive galaxy clusters to the low density "field" environment. You will use spectroscopy and imaging from Hubble Space Telescope, Very Large Telescope, Subaru telescope and the revolutionary Legacy Survey of Space and Time (LSST, https://www.lsst.org/). The results of this project will be physically interpreted through comparison with the outputs from state-of-the-art cosmological simulations of galaxy formation.

Please contact Dr John Stott for further information. This PhD project represents just one component of the research performed by the wider Astrophysics group at Lancaster University. Our PhD projects are offered on a competitive basis and are subject to availability of funding. For more general information about PhD study in Physics at Lancaster please contact our postgraduate admissions staff at py-pgadmiss@lancaster.ac.uk. You can also apply on our PhD page stating the title of the project and the name of the supervisor.

Supervisor

Dr Julie Wardlow

Description

Luminous submillimetre-selected galaxies (SMGs) and dusty star-forming galaxies are distant galaxies that are undergoing immense bursts of star formation, with typical star-formation rates of hundreds to thousands of times that of our Milky Way. These extreme systems provide challenging tests of galaxy formation and evolution theories and they seem to represent a key phase in the formation of the most massive local galaxies. However, despite ~20 years of study, they are still somewhat of a mystery -- even the physical process responsible for triggering the activity in SMGs is still a subject of intense debate. This PhD project will use data from international facilities, including the Atacama Large Millimetre/submillimetre Array (ALMA) and ESO's Very Large Telescope (VLT), to study the physical conditions in submillimetre galaxies. The results will be used to test theories of the formation and evolution of submillimetre galaxies, and probe whether they are caused by galaxy-galaxy mergers as some simulations suggest.

Please contact Dr Julie Wardlow for further information. This PhD project represents just one component of the research performed by the wider Astrophysics group at Lancaster University. Our PhD projects are offered on a competitive basis and are subject to availability of funding. For more general information about PhD study in Physics at Lancaster please contact our postgraduate admissions staff at py-pgadmiss@lancaster.ac.uk. You can also apply on our PhD page stating the title of the project and the name of the supervisor.

Supervisor

Dr Brooke Simmons

Description

Galaxies build up their complex structures over billions of years via a diverse set of processes, including interactions with other galaxies and more solitary in-situ processes. The vast majority of galaxies also host a central supermassive black hole, and these black holes accrete and grow via processes that correlate their masses with the properties of their host galaxies. Some of the most fundamental questions about these processes are not yet answered, such as: how important are galaxy mergers to the co-evolution of galaxies and supermassive black holes? By what non-merger processes can a supermassive black hole accrete enough material to sustain the observed range of luminosities at which we observe them? Are the detailed physical processes of normal matter in galaxies critical to the nature of black hole-galaxy correlations, or do such processes depend solely on more fundamental properties driven by the size and shape of the dark matter halo? With the latest generation of telescopes and high-resolution cosmological models, we are starting to answer these questions.

Investigation of these topics during a PhD project will involve data reduction and analysis of multiwavelength, multi-channel observational data, including spectroscopy and images from the Hubble Space Telescope. A key aim is to isolate and analyse the "merger-free" channel of black hole and galaxy growth, via galaxy morphological indicators. This will involve hands-on work with large datasets as well as working with and writing code. The student will join multiple established, productive communities, such as the Galaxy Zoo project. They will likely also have the opportunity to gain hands-on observing experience at world-class telescopes.

Please contact Dr Brooke Simmons for further information. This PhD project represents just one component of the research performed by the wider Astrophysics group at Lancaster University. Our PhD projects are offered on a competitive basis and are subject to availability of funding. For more general information about PhD study in Physics at Lancaster please contact our postgraduate admissions staff at py-pgadmiss@lancaster.ac.uk. You can also apply on our PhD page stating the title of the project and the name of the supervisor.

Supervisor

Dr Matthew Pitkin

Description

Gravitational waves are ripples in space-time emitted by some of the most extreme events in the Universe: colliding black holes and neutron stars. The recent observations of signals from such objects by the LIGO and Virgo gravitational-wave observatories have initiated the era of gravitational-wave astronomy, opening up a new window on the high-energy universe.

As well as the transient signals observed from such violent collisions, we also expect there to be sources of continuous signals. These would be emitted by deformed rapidly-rotating neutron stars in our own Galaxy, such as those observed electromagnetically as pulsars. This project would primarily involve looking for such signals from a range of known pulsars using data from the LIGO and Virgo gravitational-wave detectors. The project would also involve work on the astrophysical interpretation of any observed signals, the implications they would have on determining the structure of neutron stars, and the subsequent inference about the physics of the population of pulsars.

The student would become a member of the LIGO Scientific Collaboration, giving them access to data from the detectors and a range of collaboration computational resources. They would have the opportunity to spend time at one of the LIGO sites. They would be able to get involved in the analysis of some of a large number of transient signals expected to be observed as the observatories reach their design sensitivity.

The project will involve learning and using Bayesian inference methods. The project will involve software development, primarily in Python, but potential also in C. So, the project would suit someone with a strong interest in learning or developing their coding statistical analysis skills.

Please contact Dr Matthew Pitkin for further information. This PhD project represents just one component of the research performed by the wider Astrophysics group at Lancaster University. For more general information about PhD study in Physics at Lancaster please contact our postgraduate admissions staff at py-pgadmiss@lancaster.ac.uk. You can also apply on our PhD page stating the title of the project and the name of the supervisor.

Project Supervisor

Dr David Sloan

Description

Cosmology models the behaviour of our universe in terms of a small set of descriptive variables; the scale factor, Hubble parameter, relative shear expansions etc. From Einstein’s equations, we can calculate the equations of motion of these systems and find their evolution. The complete behaviour can be described in terms of dynamical systems arising from a Hamiltonian and expressed as a flow on phase space. All these descriptions rely upon factors which cannot be explicitly measured by an observer within the universe at all times. In recent work, I have shown that under certain conditions these can be extended beyond the initial singularity. One key aspect of your project will be to examine the nature of singularities in relational systems.

The goal of this project will be to develop a complete description of cosmological systems which relies only upon relational measurements and find their cosmological completions. You will develop skills in differential geometry (particularly symplectic geometry) and numerical methods alongside a strong understanding of physical systems. You will gain significant insight into the nature of singularities in general relativity and the geometry of mathematical physics.

The Physics Department is the holder of an Athena SWAN Silver award and JUNO Championship status and is strongly committed to fostering diversity within its community as a source of excellence, cultural enrichment, and social strength. We welcome those who would contribute to the further diversification of our department.

Apply Here

• Applying for postgraduate study

Supervisor

Dr Chris Arridge

Description

The magnetospheres of the giant planets are influenced by planetary ring systems and natural satellites, populations of dust, neutral gas, plasma, and radiation belts, and the host planet’s atmosphere, all embedded within the supersonic solar wind. The challenge of unravelling how these elements interact, and what physical processes are at work has been studied for over 40 years using spacecraft and ground-based observatories. Computational simulations also play an important role in investigating the physics at work in this system. In this project, the physics of Jupiter’s magnetosphere will be investigated through the use and continued development of a hybrid kinetic ion-fluid electron model of Jupiter's magnetosphere, with a particular interest in studying how plasma is transported and heated after being injected into the system from the volcanic moon Io.

Funding is available on a competitive basis. Interested candidates should contact Dr Chris Arridge (c.arridge@lancaster.ac.uk) for further information. Applicants are normally expected to have the equivalent of a first (1) or upper second class (2.1) degree in Physics, Astrophysics or a related discipline.

Supervisor

Dr Sarah Badman

Description

We are entering a new era of understanding of giant planet environments thanks to the Juno mission at Jupiter, the recent Cassini mission at Saturn, and concurrent Hubble Space Telescope images of the UV aurora. The combination of these measurements allow us to probe how the vast gas giant magnetospheres responds to changes in the external (e.g. solar wind) and internal (e.g. the volcanic moon Io) conditions. This project will exploit the available data to investigate the mechanisms and timescales of Jupiter’s and Saturn’s magnetospheric dynamics.

The successful candidate should hold a minimum of a UK MPhys Degree at 2:1 level or equivalent in a Physics-based subject. The candidate is expected to successfully work as part of a team, and to complete research suitable for the award of a PhD in Physics, including publications in high impact peer-reviewed journals. Funding is available on a competitive basis.

Please contact Dr Sarah Badman for further information.

Supervisor

Dr Licia Ray

Description

Jupiter’s upper atmosphere is connected to the local plasma environment allowing the two regions to exchange energy and angular momentum. We still don’t understand the mass flow out of the atmosphere though, which is directly affected by energy inputs into the atmosphere. This outflow can alter magnetospheric dynamics and modify coupling. We will address aspects of this interaction through the development of MI coupling theory and numerical models.

The successful candidate should hold a minimum of a UK MPhys Degree at 2:1 level or equivalent in a Physics-based subject. The candidate is expected to successfully work as part of a team, and to complete research suitable for the award of a PhD in Physics, including publications in high impact peer-reviewed journals.

Funding is available on a competitive basis. Please contact Dr Licia Ray for further information.

Supervisor

Dr Elisabetta Boella

Description

The solar wind is a flux of plasma, e.g. ionised particles, constantly irradiated by the sun. Its existence was predicted by Eugen Parker in 1958 and later confirmed by several space missions. Since then, our insight into the dynamics of the solar wind has evolved tremendously, but many open questions remain. In particular, the identification of the physical mechanisms that regulate the energy budget of the solar wind is still a challenge.

Plasma in the solar wind is almost collisionless. Therefore, its evolution is mainly determined by the interaction between waves of different nature and the plasma particles. This PhD project is dedicated to exploring plasma waves and instabilities in the solar wind using theoretical frameworks and cutting-edge numerical simulations. This work will shed light on the microphysics governing the solar wind and its effects on macroscopic solar wind parameters. Simulations modelling solar wind conditions will allow identifying the physical processes that govern the solar wind energy balance. They will clarify the contribution of the different solar wind components to the energy budget. Furthermore, the theory and modelling effort will also provide crucial support to the interpretation of data from current space missions, such as Parker Solar Probe and Solar Orbiter. These spacecrafts are currently sampling the solar wind with an unprecedented level of detail. By using simulations and observations, the project is then expected to provide a new understanding of the energetics of the solar wind.

Through this project, the candidate will:

- Learn about plasma physics and space plasmas

- Contribute to and use massively parallel codes which the student will deploy and run on the most powerful supercomputers in the world

- Develop data analysis skills employing also forefront machine learning techniques

Funding is available on a competitive basis. Potential applicants are encouraged to contact Dr. Elisabetta Boella e.boella@lancaster.ac.uk for more information. They are also encouraged to send their applications via https://www.lancaster.ac.uk/physics/study/phd/#d.en.340732

Supervisor

Professor Roger Jones

Description

The PhD will analyse new data from the world’s largest collider, LHC, situated in CERN. The data are taken after the LHC upgrade to an energy of 13 TeV. After the enormous success of the LHC in 2010-2012, culminating with finding the Higgs particle, we have now opened a new chapter in the search for New Physics. The high precision measurements of B-hadron decays allow for indirect searches for new physics, where new particles that are produced virtually alter the decays so they do not follow rules of the Standard Model. This builds on Lancaster’s leading role in the ATLAS analysis of the 2010-2012 data to search for SUSY in CP-violating of Bs-decays, which led to 3 publications in influential journals. From 2015 ATLAS has an upgraded Inner Detector with additional pixel layer (IBL), which has substantially increased a lifetime measurement precision. This change will allow ATLAS to measure CP violation in Bs meson decays with unprecedented precision and will increase the potential for finding possible SUSY effects.

We propose two distinct physics measurements, both searching for New Physics in CP violation. They study the decay channels Bs ➔J/ψφ and Bs ➔J/ψKK. The methodology is similar, while a physics potential is different. These two measurements are complementary to each other, and the conclusion on CP effects can be only done by performing both. Also, we propose a high precision measurement in channel B+ ➔J/ψK+, which is both a stringent test of the detector performance and calibration and has new interesting physics information in its own right.

Supervisor

Professor Roger Jones

Description

The PhD will analyse new data from the world’s largest collider, LHC, situated in CERN. The data are taken after the LHC upgrade to an energy of 13 TeV. After the enormous success of the LHC in 2010-2012, culminating with finding the Higgs particle, we have now opened a new chapter in the search for New Physics. This proposed search for displaced supersymmetric (SUSY) particles is an example of a “direct search” in which the signal would be distinguished by an excess of displaced vertices relative to those coming from Standard Model. The search will look for events with a pair of leptons (muons, electrons) produced at a point between 0.01 cm and 2 cm from the original collision sideways from the beams. The search will be designed to be sensitive to a wide range of SUSY models with non-prompt di-lepton final states. From 2015 has an upgraded Inner Detector with additional pixel layer (IBL) that has substantially increased the precision with which the production point of the lepton pair can be resolved. This change will allow ATLAS to hugely improve the signal/ background separation for SUSY particles decaying in the range we will study.

The PhD will study two decay channels, searching for displaced supersymmetry in oppositely charged muon-muon pairs and electron-muon pairs. While the selections are different, the methodology is similar: in both cases, the central part of the analysis is the reconstruction of the displaced vertex and the impact parameters of leptons.

Supervisor

Professor Roger Jones

Description

We are working on the ATLAS experiment at the CERN Large Hadron Collider. Our main work concerns the search for the signatures of new physics processes. We wish to address the big questions: Why is there a matter/antimatter asymmetry in our universe? What is the nature of dark matter? Are there additional forces to the four in the Standard Model of particle physics? Unusually, we use the same techniques to search for new physics directly (though the search for new particles) and indirectly (through the effect of new particles, too massive to be produced directly, on very precisely measured quantities). The common themes are in our areas of expertise: the precise measurement of the tracks left by particles and the lifetimes of decaying particles; the fast identification (so-called “triggering”) of relatively low momentum muons; and the stringent control of backgrounds to the physics signals coming from particles containing beauty quarks.

The successful candidate will work on the search for new particles that live long enough to decay in the tracking detector of the ATLAS experiment, then decay to produce muons; and investigate the matter-antimatter asymmetry parameters in the decay of B_s particles.

If they wish, the student will have to opportunity to work on a smaller experiment looking at the rare decays of kaons, which can also reveal new physics departures from the Standard Model.

The student will be able to work on the software and large-scale computing for the experiment and use data science techniques in particle physics. The student would normally spend 18 months in Geneva working closely with an international team of experts on the experiment.

Please contact: Professor Roger Jones (roger.jones@lancaster.ac.uk) for further information. Students interested in this PhD studentship should apply via the .

Applicants are normally expected to have the equivalent of a first (1) or upper second (2.1) degree class in Physics or Astrophysics.

The Lancaster Physics Department holds an Athena SWAN silver award and JUNO Champion status, and is strongly committed to fostering inclusion and diversity within its community.

Closing Date

Application deadline is Jan 31, 2021. Late applications will be considered until all positions are filled.

Funding notes

It is expected that the STFC will fund the project. Full funding for fees and stipend for this project would be available to those with established residency in the UK (Residency restrictions apply). Applications from overseas citizens will be considered, provided the applicant has access to an alternative source of funding.

Supervisor

Dr Harald Fox

Description

At Lancaster, we work on the Higgs boson decay mode into two tau leptons. With this channel, we contributed to the Higgs discovery in 2012. There are two projects possible exploiting this particular final state.

The first project is investigating the Higgs boson further. The di-tau final state is the most accessible fermionic final state. Measuring the Higgs branching ratio into fermions directly is one of the tests of the Standard Model. Anomalous couplings of the Higgs boson would be a hint of new physics. The di-tau signal also allows one to measure the CP properties of the Higgs boson. The Standard Model predicts a CP-even (scalar) Higgs with no CP violation in the production or decay. On the other hand, we know that there is not enough CP violation in the quark sector of the Standard Model to explain the existence of the universe. Observation of a new source of CP violation is hence necessary. Measuring the Higgs couplings and its CP properties is hence an important test for the Standard Model.

The second project uses the Higgs boson as a portal to new physics beyond the Standard Model. Here we are investigating the production of two Higgs bosons together, where one decays into a pair of b-quarks and the other into a pair of tau leptons. Di-Higgs production is predicted by the Standard Model and will be used to determine the exact shape of the Higgs (Mexican hat) potential. However, other processes predict an enhancement of this signal, e.g. the decay of Randall-Sundrum gravitons or the decay of further, heavy Higgs bosons. In this project, you will be looking for new physics beyond the Standard Model in this decay mode.

Supervisor

Dr Daniel Muenstermann

Description

Future particle experiments will impose extreme requirements on their tracking detectors, taking today's silicon sensor technology to the very limit. To extend the physics reach of the LHC for example, upgrades to the accelerator are planned which will increase the peak luminosity by a factor 5 to 10. This will lead to much-increased occupancy and radiation damage of the sub-detectors, requiring the exchange of the current inner trackers with all-silicon ones.

Lancaster has a long-standing tradition of silicon detector R&D in CERN's RD50 collaboration and is now focusing on R&D for future pixel detectors – the innermost sub-detector of particle physics experiments and thus exposed to the harshest conditions. Possible PhD projects would include irradiation and characterisation of prototype planar pixel sensors, which are the baseline choice for all LHC detector upgrades and CLIC.

Beyond those, the PhD project may also involve the characterisation of novel HV-CMOS pixel sensors which promise very good radiation tolerance while being extremely lightweight and cost-efficient. The first large-area prototype chip has just been received from the foundry; initial results from this chip are eagerly awaited by the community and could be part of the PhD project.

Supervisor

Dr Laura Kormos

Description

The Tokai-to-Kamioka (T2K) long-baseline neutrino oscillation experiment sited in Japan is well-established and was the first experiment to indicate that mixing occurs between all three neutrino flavours. This finding opened the door to leptogenesis, in which neutrinos play a major role in the formation and evolution of our matter-dominated universe, which as yet is unexplained. Recent results from T2K suggest that we may be on the brink of discovering yet another necessary ingredient for this hypothesis: CP violation in the lepton sector. However, at present T2K cannot make a definitive statement because it doesn't have enough data. As we collect more data, we also must reduce our systematic uncertainties to ensure that they don't become the limiting factor in our understanding of the matter-antimatter asymmetry. One of the largest uncertainties is our understanding of neutrino interactions. The student on this project would work on this problem in two ways: by measuring the rates in the T2K off-axis near detector of neutrino interactions on various nuclei that result in the production of specific particles, and by comparing the results to the predictions of the models and subsequently playing a role in modifying the models. This will lead to a published cross-section measurement in an area where there are few or even none. T2K has had impressive success with using data from the near detector to constrain the uncertainties in their oscillation results (it halves them), and the constraints provided by measurements such as the ones above are key to measuring matter-antimatter asymmetry via neutrino oscillations. The student also will spend some months on-site in Japan, acting as a detector expert and doing data-taking shifts.

Supervisor

Dr Laura Kormos

Description

The SNO+ experiment, sited at SNOLab in Canada, aims to search for neutrinoless double-beta decays in Te-130. If observed, these decays would demonstrate that neutrinos are Majorana particles, a necessary condition for a theoretical hypothesis called leptogenesis in which neutrinos provide enough matter-antimatter asymmetry in the early universe to explain its existence. But SNO+ can address many other areas of neutrino and particle physics as well. Detector commissioning began in November 2016, to be followed with some months of data-taking with the detector full of ultra-pure water, then with the scintillator, and finally, the Te-130 will be added. This large, deep-underground detector allows us to search for nucleon decay, dark matter candidates, and make significant contributions to our understanding of geophysical, reactor and solar neutrinos. The student on this project would explore one or more of these topics using the SNO+ data, leading to a publication. The student will also spend some months on-site in Canada, operating the detector and doing data-taking shifts.

Supervisor

Dr Helen O'Keeffe

Description

The SNO+ experiment is a multi-purpose 1 ktonne liquid scintillator experiment that will study low energy neutrinos from a variety of sources. With the addition of 130Te to the scintillator, a search for neutrinoless double-beta decay will be performed to yield information on whether the neutrino is a Dirac or Majorana particle. Possible PhD projects include the study of low energy radioactive backgrounds and their impact on the sensitivity to neutrinoless double beta decay and/or solar neutrino physics. The project would include aspects of laboratory work, data analysis and computer simulation. It is expected that PhD students would spend 9-12 months on-site in Canada.

Supervisor

Dr Helen O'Keeffe

Description

The Tokai to Kamioka (T2K) experiment is a long-baseline neutrino oscillation experiment located in Japan. An intense beam of muon neutrinos is created in Tokai and its composition is measured 280 m and 295 km downstream of the neutrino production point. Comparison of the beam composition measured by the two detectors yields information on whether neutrino oscillations have occurred. Hyper-Kamiokande is the next-generation experiment planned to follow on from T2K. Possible PhD projects include measurements of (anti)-neutrino neutral pion production in the T2K near detector and sensitivity studies for the Hyper-Kamiokande experiment.

It is expected that PhD students would spend 9-12 months on-site at the near detector in Japan supporting ECal and/or DAQ operations.

Supervisor

Dr Andrew Blake

Description

The MicroBooNE experiment has recently begun operating in the Booster neutrino beamline at the Fermi Laboratory near Chicago USA. Its 100-ton detector is pioneering the use of Liquid Argon Time-Projection technology and offers the ability to measure neutrino interactions with unprecedented spatial and calorimetric precision. Over the coming years, MicroBooNE will perform new measurements of accelerator neutrinos and will demonstrate the exquisite imaging capabilities of Liquid Argon technology. It will also shed new light on previous experimental results from the MiniBooNE and LSND experiments, which hint at the existence of a fourth species of sterile neutrino, a potentially major discovery. In 2018, MicroBooNE will be joined in the beamline by the Short-baseline Near Detector (SBND), providing a high-statistics neutrino data set and a powerful multi-detector search for sterile neutrinos. The Lancaster neutrino group is currently working on neutrino event reconstruction and data analysis for MicroBooNE, and detector construction and software development for SBND. A new PhD student would collaborate on the operation of MicroBooNE, commissioning of SBND, analysis of data, and publication of neutrino physics results. It is expected that the student would spend a long-term attachment at the Fermi Laboratory.

Supervisor

Dr Jaroslaw Nowak

Description

The protoDUNE is a full-scale engineering prototype of the DUNE far detector and will be the largest Liquid Argon Time Projection Chamber (LArTPC) detector with almost 1kTon mass. protoDune will be placed at CERN on a test beam to aid the future long-baseline experiments with reduction of the systematic uncertainties. One of the highest uncertainties comes from hadrons interaction in the medium after they are produced in the neutrino interactions. The PhD projects will focus on the measurement of the pion and kaon cross-sections on argon for particles with momenta from about 500MeV/c to 7GeV/c. PhD candidates will be required to spend significant time at CERN and help with the installation and operation of the detector.

Supervisor

Dr Jaroslaw Nowak

Description

In the last decade measurements from several neutrino experiments (MiniBooNE, NOMAD, MINERvA, T2K) showed that our understanding of neutrino cross-sections is limited. The introduction of new processed (MEC, 2p-2h) which caused a paradigm shift in the way we think about the nuclear effects. Our understanding of the neutrino interaction cross-sections and cross-sections of the hadrons with the medium after they are created in the neutrino interactions are necessary to achieve a reduction of the systematic uncertainties required by the future long-baseline experiments, which will measure CP violation in the neutrino sector.

Several PhD projects are available: precise neutrino cross-section measurements with any of the experiments the Lancaster group is a member (T2K, MicroBooNE, SBND), development of NuWro neutrino Monte Carlo generator, measurement of proton and pion interactions on argon with the two test beam experiments at CERN (protoDUNE and HPTPC). PhD candidates will be required to spend about one year overseas to help with the operation of the experiment.

Supervisor

Dr Laura Kormos

Project Description

The Tokai-to-Kamioka (T2K) long-baseline neutrino oscillation experiment sited in Japan is well-established and was the first experiment to indicate that mixing occurs between all three neutrino flavours. This finding opened the door to leptogenesis, in which neutrinos play a major role in the formation and evolution of our matter-dominated universe, which is yet unexplained. Recent results from T2K suggest that we may be on the brink of discovering yet another necessary ingredient for this hypothesis: CP violation in the lepton sector. However, at present T2K cannot make a definitive statement because it doesn't have enough data. As we collect more data, we also must reduce our systematic uncertainties to ensure that they don't become the limiting factor in understanding the matter-antimatter asymmetry. One way we do that is by using data from our near detector, the ND280, to constrain the models used to predict the data at the far detector, Super-Kamiokande, via which the neutrino oscillation parameters are measured.

The student on this project would improve the selections of ND280 data that we use as input to constrain the models and produce the data fits and associated analyses. Also, there's an opportunity for the student to play a role in the successor to the T2K experiment, Hyper-Kamiokande, which is scheduled to begin taking data around 2027. The student also will spend some months on-site in Japan, acting as a detector expert and doing data-taking shifts.

Please contact Dr. Laura Kormos (l.kormos@lancaster.ac.uk) for further information. Students interested in this PhD studentship should apply via the Lancaster University admission system.

Applicants are normally expected to have the equivalent of a first (1) or upper second (2.1) degree class in Physics or Astrophysics. The Lancaster Physics Department holds an Athena SWAN silver award and JUNO Champion status and is strongly committed to fostering inclusion and diversity within its community.

Closing Date

Application deadline is Jan 31, 2021, Late applications will be considered until all positions are filled.

Funding Notes

It is expected that the STFC will fund the project. Full funding for fees and stipend for this project would be available to those with established residency in the UK (Residency restrictions apply). Applications from overseas citizens will be considered, provided the applicant has access to an alternative source of funding.

Supervisor

Dr. Jarek Nowak

Project Description

The standard model of particle physics accommodates three active flavours of neutrino, which interact with matter via the weak nuclear force. In recent years, a number of experimental observations have hinted at a new type of sterile neutrino, beyond the current standard model. If confirmed, this would be a major discovery and would fundamentally alter our understanding of neutrino physics.

The short-baseline neutrino programme, currently under construction at the Fermi Laboratory in the USA, will conduct a multi-detector search for sterile neutrinos using an accelerator neutrino beam and three large Liquid Argon Time Projection Chambers: SBND, MicroBooNE and ICARUS. The MicroBooNE experiment is already taking data at Fermilab, while SBND and ICARUS will begin operating in the coming year. The use of LAr-TPC detector technology offers the ability to measure neutrino interactions with exquisite spatial and calorimetric resolution, ideal for precision studies of neutrino physics. The Lancaster neutrino group is working on modelling of neutrino interactions and data analysis for the short-baseline neutrino programme, with a focus on precision measurements of neutrino interactions with argon nuclei to enable and extend the physics reach of the experiments. The group has also collaborated on the first neutrino physics results from MicroBooNE, and the construction of hardware components for SBND.

The goal of this project is to search for evidence of sterile neutrinos at the Fermilab short-baseline programme. The student will work on the analysis of the data and will also collaborate on the installation and commissioning of the SBND detector as it comes online. The project offers an excellent opportunity to experience all aspects of a particle physics experiment from detector commissioning through to physics analysis. The student would also have the chance to spend a significant period of time working onsite at the Fermi Laboratory.

Please contact Dr. Jarek Nowak (j.nowak@lancaster.ac.uk) for further information. Students interested in this PhD studentship should apply via the Lancaster University admission system.

Applicants are normally expected to have the equivalent of a first (1) or upper second (2.1) degree class in Physics or Astrophysics. The Lancaster Physics Department holds an Athena SWAN silver award and JUNO Champion status and is strongly committed to fostering inclusion and diversity within its community.

Closing Date

Application deadline is Jan 31, 2021. Late applications will be considered until all positions are filled.

Funding Notes

It is expected that the STFC will fund the project. Full funding for fees and stipend for this project would be available to those with established residency in the UK (Residency restrictions apply). Applications from overseas citizens will be considered, provided the applicant has access to an alternative source of funding.

Supervisor

Dr Jonathan Gratus (Lancaster University)
Dr Hywel Owen (Manchester University)

Description

A studentship is available from Oct 2020 on the development of the theory, computer coding and testing of an exciting new idea for improving the numerical simulation of charged particles. Particle-in-cell (PIC) codes are essential for the numerical simulation of charged particles in both conventional accelerators and plasmas. They are used extensively for understanding of the physics and design of future machines. A typical code may have to track tens of billions of particles and may need to run on high performance computer clusters. We are investigating a revolutionary new method which promises to dramatically reduce the computation needed for simulations. This method increases the dynamical information of each particle while reducing the total number of particles. To aid in this task we need an enthusiastic PhD student to incorporate the new dynamical equations into existing PIC codes and compare the results with standard simulations.

For the student of a more theoretical consideration there is the opportunity to develop the theory using powerful tools of differential geometry and general relativity.

The applicant will be expected to have a first or upper second class degree in mathematics, physics, computer science, engineering or other appropriate qualification.

A full graduate programme of training and development is provided by the Cockcroft Institute.

Potential applicants are encouraged to contact Dr Jonathan Gratus (j.gratus@lancaster.ac.uk) for more information.

Supervisor

Dr Ian Bailey

Description

The Fermilab muon g-2 experiment is attempting to measure the anomalous magnetic moment of the muon: a quantity which is sensitive to the existence of ‘new physics’. The magnetic moment will be determined by measuring the energies and directions of electrons coming from the decay of a beam of muons orbiting inside a storage ring. In this project, you will learn skills in accelerator beam dynamics as part of the Cockcroft Institute of Accelerator Science and Technology. You will apply these skills to enhance simulations of the g-2 muon spin dynamics and help analyse the experimental data as part of the g-2 collaboration.

Supervisors

Dr Ian Bailey
Professor Yuri Pashkin
Dr Edward Laird

Description

In recent years, there has been a growing interest in the 'hidden sector' and non-traditional dark matter candidates such as axions and dark photons. If either of these hypothetical particles exists, they can be detected through their interaction with strong magnetic fields. This interaction should lead to the generation of photons whose frequency is related to the mass of the hypothetical particles. This calls for the development of sensing techniques that are capable to detect extremely weak electromagnetic signals in a wide frequency range.

There are growing efforts around the UK to undertake a nationwide project aimed at the detection of axions and dark photons using various methods. Superconducting quantum circuits offer the possibility to build amplifiers with extremely low noise temperature covering a wide frequency range.

In this project, you would have opportunities to develop superconducting detector technologies and/or develop computer simulations to optimise the sensitivity of future resonant detectors of axions and dark photons. This project will be undertaken in collaboration with the University of Sheffield and the Cockroft Institute. You may also have the opportunity to work on either the ADMX experiment in the US or planned experiments in the UK. In the latter case, you will use nanofabrication and cryogenic facilities of the Lancaster Quantum Technology Centre.

Supervisor

Professor Steven Jamison

Description

We seek a PhD candidate to undertake experimental research on laser-driven relativistic particle beam acceleration. The research will be carried out at STFC Daresbury National Laboratory, in an exciting and collaborative project involving students and staff from Lancaster University, University of Manchester and STFC Daresbury National Laboratory.

Relativistic particle acceleration driven by ultrafast optical lasers holds potential to revolutionise high energy particle accelerators. In the application of ultrafast electron diffraction, laser-driven acceleration offers control of particle beams on the femtosecond (10^-15s) time scale. Also, the high-field strengths available in ultrafast lasers may enable orders of magnitude reduction in size and cost of kilometre-scale accelerators of x-ray-free-electron lasers and high-energy particle physics.

The successful candidate will join a research team developing novel acceleration concepts using ultrafast lasers, and working towards several proof-of-concept demonstrations of laser acceleration of relativistic beams. They will carry out work in the optimisation of multi-MV/m optical and infrared sources, in high-field non-linear optics, in mm-scale accelerating structures, and in developing systems for the experimental demonstration of acceleration of relativistic beams. Through their research with high-power laser and electron-beam facilities, they will develop skills in ultrafast laser science, in relativistic particle beams physics, and the theory and modelling of ultrafast optics and particle dynamics.

The applicant will be expected to have a first or upper second class degree in physics, medical physics, electrical engineering or other appropriate qualification. A full graduate programme of training and development is provided by the Cockcroft Institute. The student will register at the Lancaster University, supervised by the THz acceleration project lead, Professor Steven Jamison.

The student will join a vibrant group of students and post-doctoral researchers already making significant progress in this area. The studentship will also work closely with scientists and Engineers at STFC Daresbury Laboratory National Laboratory. There will also be opportunities for travel and collaboration with scientific institutes and universities outside the U.K.

The Physics Department is a holder of an Athena SWAN Silver award and JUNO Championship status and is strongly committed to fostering diversity within its community as a source of excellence, cultural enrichment, and social strength. We welcome those who would contribute to the further diversification of our department.

Interested candidates should contact Professor Steven Jamison s.jamison@lancaster.ac.uk for further information. For general information about PhD studies in Physics at Lancaster please contact our postgraduate admissions staff at py-pgadmiss@lancaster.ac.uk. You can apply directly at http://www.lancaster.ac.uk/physics/study/phd/ stating the title of the project and the name of the supervisor in your application.

Closing Date

Applications will be accepted until the post is filled.

Supervisor

Dr Elisabetta Boella

Description

Magnetic reconnection is a fundamental process occurring in magnetized plasmas. It consists of a sudden and rapid change of the magnetic field topology accompanied by the release of magnetic energy [1]. Magnetic reconnection events are pervasive in space, astrophysical and laboratory plasmas.

Extensive theoretical, numerical, experimental, and observational works have contributed to clarifying many aspects of the dynamics of magnetic reconnection during the last two decades. Nevertheless, several open challenges still prevent a deeper comprehension of the process. This PhD project focuses on the so-called energetics problem (e.g., how the energy released during the explosive event is converted into high-speed flows, heat and energetic particles) and plans to advance our knowledge on this topic through massively parallel fully kinetic simulations.

Simulations based on the Particle-In-Cell technique will address both astrophysical and laboratory scenarios. The fast progress in laser technology offers an amazing opportunity to explore magnetic reconnection in the laboratory with properly scaled experiments. Indeed, reproducing astrophysical processes in the laboratory under controlled conditions is a promising path to gain physical insights that would be otherwise inaccessible. Numerical simulations play a critical role as they allow for identifying the proper configurations where magnetic reconnection can be explored using ultra-intense lasers.

The successful candidate will join a vibrant team developing a cutting-edge research program on plasma kinetic simulations. They are expected to interact with colleagues at Lancaster University and the Cockcroft Institute (STFC Daresbury Laboratory National Laboratory, Warrington) working on complementary subjects. There will be the possibility to collaborate with researchers based in scientific institutes and universities in and outside the U.K.

Through the development of this project, the student will acquire skills and expertise in plasma physics, laser-matter interaction, high-energy-density-physics, numerical techniques, and high-performance-computing.

Interested candidates should contact Dr Elisabetta Boella (e.boella@lancaster.ac.uk) for further information.

[1] E. G. Zweibel and M. Yamada, Annu. Rev. Astron. Astr. 47, 291 (2009).

Supervisors

Professor Steven Jamison - Lancaster University

Associated project supervisors: Dr D Graham / ProfessorR Appleby - University of Manchester, Department of Physics

Lancaster University, together with collaborators at University of Manchester and the Cockcroft Institute for particle accelerator science, have developed internationally leading approaches to laser-driven particle accelerators. Our research, which involves a combination of femtosecond laser non-linear optics and sub-mm structures for electromagnetic-electron beam interactions, featured as the cover article in Nature Photonics in December 2020†.

Opportunities are now available for talented physicists to join our research programme as a PhD student, in either experimentally focused or theory/simulation focused projects.

• The experimentally-focused studentship will investigate the interaction of intense THz electromagnetic pulses (generated by non-linear optics and ultrafast lasers) with 100keV and >50 MeV electron beams.
• The theory/simulation-focussed studentship will investigate the mechanisms of energy depletion and back reaction on the electromagnetic field during extremely high gradient (GV/m) and ultrafast (few femtosecond) conditions.

The student will join a vibrant team of PhD students and post-doctoral researchers from Lancaster University and University of Manchester. The research team have extensive laser and electron beam experimental facilities at STFC Daresbury National Laboratory, Lancaster and Manchester universities, and access to relativistic beam test accelerators at the National Laboratory.

Supervisor

Dr Jonathan Gratus

Description

PIC codes are used extensively in both conventional beam dynamics and laser-plasma interactions. Macro-particles are essential given the large number of particles one wishes to simulate. To calculate the input for Maxwell's equations, the charge and current of each macro-particle is \smeared" or \diluted" over the nearest cell points.

We propose an improved method of modelling the macro-particles. Current PIC codes only record the position and velocity of each macro-particle. By contrast, our new method will record higher moments. These new super-macro-particles (SMPs) will then have to be smeared over a large number of cells, the higher moments being used to reconstruct the phase space distribution of charge. This method will increase the sophistication of the algorithm, albeit at a small cost compared to the usual method of simply increasing the number of macro-particles. The potential advantages, however, may be huge, equivalent to replacing tens or hundreds of macro-particles with a handful of these new SMPs. Indeed, if enough moments are chosen, an entire bunch of particles could be represented by a single SMP.

There are two key steps for the successful implementation of this algorithm. The rest is to calculate the correct dynamical equations for the moments. The second is the reconstruction of the phase space distribution for each SMP. Using powerful techniques of differential geometry, JG has already shown that the equations of motion for the quadrupole moment have unexpected features. [1]

By October 2019 a general analytic formula for both the dynamics of the SMPs and the reconstruction of the distribution will have been calculated and we are looking for a PhD student to help implement this algorithm. As a prelude to full-scale 3-dimensional implementation, lower-dimensional codes could be run and benchmarked against existing codes.

The SMP approach will be excellent at calculating CSR wakes where the distance between the centres is large. There is also the possibility of incorporating space-charge into SMPs. Radiation reaction is difficult to model for standard macro-particles as the only information is position an velocity. However, since SMP have information about higher moments one can model space-charge by altering the equation for the second and higher moments.

Currently, we wish to develop the algorithm and demonstrate proof of principle. However, it is hoped the code could be applied to several existing projects, in particular, FELs where the CSR is so important.

As far as is known to the proposers (after searching) no similar approach has been considered. Although several people, starting with Esirkepov [2] and including Vay et al [3] do consider smearing the macro-particles over several cells with a chosen shape.

Program of PhD: We will search for a student with an interest in programming. In the first year, as well as the CI lectures, the student will learn the necessary differential geometry and theory of distributions to understand the nature of the algorithm. They will also improve their coding skills maybe leading to writing a simple 1d PIC code. She or he will then implement a 1d SMP can compare the result. In years two and three the student will familiarise themselves with an existing 3d PIC code and implement the SMP.

References

[1] Gratus, J., Banaszek, T. \The correct and unusual coordinate transformation rules for electromagnetic quadrupoles" Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences. Volume 474, 2213 (2018)

[2] \T.Zh. Esirkepov, Exact charge conservation scheme for Particle-in-Cell simulation with an arbitrary form-factor", Computer Physics Communications, Volume 135, Issue 2, 144 (2001)

[3] J.-L. Vay, C.G.R. Geddes, E. Cormier-Michel, D.P. Grote, \Numerical methods for instability mitigation in the modelling of laser wakefield accelerators in a Lorentz- boosted frame," Journal of Computational Physics, Volume 230, Issue 15, 5908 (2011)

Supervisor

Dr Jonathan Gratus

Description

Background: The successful collaboration of Jonathan Gratus, Rosa Letizia, Paul Kinsler, Taylor Boyd and Rebecca Seviour [1, 2, 3], has shown that the electric field profile in a waveguide or cavity can be shaped using a wire medium with varying wire radius. Using space-time symmetry it is reasonably straightforward to convert the concept of spatial dispersive inhomogeneous media into time and frequency-dependent media. Thus one can relatively quickly arrive at the time-dependent permittivity one will need to shape an electron bunch. The challenge for the numerical simulation of this model is the challenge of implementing directly time-dependent media.

This project will support a $1.4million EPSRC proposal (Gratus, Letizia, Kinsler, Seviour (Huddersfield), McCall (Imperial)) which among other things will experimentally verify the existence of wave profile shaping in wire media.

Taylor Boyd, who as a result of this project has 4 peer-reviewed journal articles will be submitting soon. The work is ideally suited for a PhD student.

Program of PhD

During the first year, as well as undergoing the Cockcroft postgraduate training, the student will learn about spatially and temporally dispersive, time-dependent and inhomogeneous media. Also, they would learn to run CST and run the profiles already develop successfully by our collaboration. He or she will then be able to develop the time-dependent proles necessary for bunch shaping. These theoretical results could be verified using a simple 1D EM solver. In year 2 the student will explore VSim together with the extension of open source code such as MEEP and MPB to go to 3D.

References

[1] Taylor Boyd, Jonathan Gratus, Paul Kinsler, Rosa Letizia and Rebecca Seviour \Mode profile shaping in wire media: towards an experimental verification." Applied Sciences, Vol. 8, No. 8, 1276, 01.08.2018.

[2] Taylor Boyd, Jonathan Gratus, Paul Kinsler and Rosa Letizia \Customizing longitudinal electric field profiles using spatial dispersion in dielectric wire arrays." Optics Express, Vol. 26, No. 3, 05.02.2018, p. 2478-2494.

[3] Taylor Boyd, Jonathan Gratus, Paul Kinsler and Rosa Letizia \Subwavelength mode profile customisation using functional materials." Journal of Physics Communications, Vol. 1, No. 2, 025003, 06.09.2017.

Supervisors

Dr Jonathan Gratus (Lancaster) and Professor Rebecca Seviour (Huddersfield)

Description

An opportunity has arisen to undertake a PhD at one of the UKs top universities in the area of engineered spatially dispersive materials. A class of materials that are artificially created, like metamaterials, where the materials constitutive parameters depend, spatially, on the wavevector. The successful applicant will join an established national collaboration of theoreticians and experimental physicists and engineers working in the area of engineered spatially dispersive materials. The student will build upon recent work by the collaboration using established numerical tools to further develop our understanding of the properties of these interesting materials, and enable their physical realisation.

Engineering spatial dispersion can offer many advantages to current RF technologies. Using spatially dispersive media may enable the EM field profile of a propagating wave to have an engineered field profile, engineered to present peak EM fields at the aperture of antennas. This may enable a fundamental shift in MIMO technologies, i.e. optimising waveform profiles for exploitation.

Project Programme of work:

Building upon previous work the student will start by using the commercial numerical EM 3D solvers HFSS, CST and Comsol.

(1) the student will investigate the effects of disorder on the predicted longitudinal modes in shaped wire array media. The simulations will focus on a 4x4 array of wires, with varying degrees of variation of wire position and wire radius. Variations will be chosen from a uniform random distribution, representing variations in coordinate position of the wire and radius, starting with 1%, 2%, 5% and 10%. For each of these sets of variations at least 100 disorder ensembles will be modelled. The effects of the disorder on longitudinal mode and electric field profile will be analysed, look at the extrema and average responses. The effect of disorder only on position and radius will be studied both separately and jointly.

(2) The student will start to model a physical realisable spatially dispersive wire array media capable of supporting longitudinal EM waves, using time-domain simulations.

a. Time domain simulations of wire array media loaded in an oversized waveguide. Looking at longitudinal electric field patterns, optimising the field structure, modelling the wire media with physically realisable materials and with maximal variations from (1) that still enable the realisation of longitudinal electric modes, optimised for 1GHz.

b. Model 1GHz longitudinal electric field wave propagation in standard waveguide.

c. Design and model a coupling/matching section that will couple the longitudinal electric field wave propagation in (b) to the oversized wire media loaded in oversized waveguide of (a).

d. Parallel work: look to engineer a wire array media, between two antennas, that by design the electric field profile has a peak amplitude at the points of contact with the antennas.

A full graduate programme of training and development is provided by the Cockcroft Institute.

Potential applicants are encouraged to contact Dr Jonathan Gratus (j.gratus@lancaster.ac.uk) for more information.

Supervisor

Dr Elisabetta Boella

Description

Laser wakefield accelerators (LWFA) are able to sustain accelerating gradients orders of magnitude larger than radio-frequency accelerators. Therefore, they represent a possible compact and cheaper alternative to conventional acceleration methods [1]. They also constitute a potential novel light source [2]. Thus, they open up promising perspectives for future compact and affordable electron and x-ray light sources, hence enabling possible revolutionary advances in science, industry, medicine, and technology. However, at the current status, the electron beam quality and stability, as well as the radiation that they generate, do not meet yet the standard for applications. Achieving high-quality beams and high-brightness radiation from LWFA are major challenges in the field.

Within this PhD project, we intend to tackle these major challenges. Leveraging high-fidelity numerical simulations, we aim at improving the electron beam and x-ray characteristics focusing on optimizing how electrons get trapped into the accelerating structure.

The successful candidate will join a vibrant research team developing novel acceleration concepts using ultra-intense lasers and working towards several proof-of-concept demonstrations of laser-driven particle acceleration. They will interact with eminent theoretical and experimental physicists making significant progress in the field. Their theory and simulation effort will enable and support forefront experiments at the STFC Daresbury Laboratory National Laboratory (Warrington) and other national and international facilities.

Through the development of this project, the student will acquire skills and expertise in plasma physics, laser-matter interaction, high-energy-density-physics, numerical techniques, and high-performance-computing. They will be registered at Lancaster University. They will also enrol in the graduate program at the Cockcroft Institute, part of STFC Daresbury Laboratory National Laboratory. Finally, they will have the opportunity to travel and collaborate with scientific institutes and universities in and outside the U.K.

Interested candidates should contact Dr Elisabetta Boella (e.boella@lancaster.ac.uk) for further information.

[1] Tajima & Dawson, Phys. Rev. Lett. 43, 267 (1979); Esarey et al. Rev. Mod. Phys. 81, 1229 (2009).

[2] Corde et al., Rev. Mod. Phys. 85, 1 (2013); Albert & Thomas, Plasma Phys. Contr. F. 58, 103001 (2016).

Supervisor

Dr Elisabetta Boella

Description

A PhD project is available from October 2022 on numerical modelling of laser-driven ion acceleration. The research will be carried out within the Cockcroft Institute of Accelerator Science and Technology in an exciting and collaborative environment involving students and staff from Lancaster University and University of Strathclyde.

Ultra-intense laser pulses can rapidly ionise matter and excite accelerating fields that are orders of magnitude higher than those characterising conventional accelerators. These extreme fields could be exploited for accelerating ions to high energies in short distances. Thus, these laser-driven ion sources may hold the key towards miniaturised compact accelerators, with broad scientific, technological and societal implications.

The PhD student will work on modelling from a numerical and theoretical point of view the production of energetic ion beams via laser-plasma interaction. They will perform simulations based on the Particle-In-Cell technique using some of the fastest supercomputers in the world. Their research will be developed in close-collaboration with experimental colleagues at Scottish Centre for the Application of Plasma-based Accelerators (University of Strathclyde) with the possibility of directly being involved in experimental campaigns.

The applicant will be expected to have a first or upper second class degree in physics or other appropriate qualification. A full graduate programme of training and development is provided by the Cockcroft Institute.

Potential applicants are encouraged to contact Dr. Elisabetta Boella (e.boella@lancaster.ac.uk) for more information. They are encouraged to send their applications via https://www.lancaster.ac.uk/physics/study/phd/#d.en.340732 and http://www.cockcroft.ac.uk/join-us

Supervisor

Professor Steven Jamison

Project

Lancaster University, Department of Physics & Cockcroft Institute

A studentship is available from October 2022 for a motivated and inquisitive physicist to undertake experimental and theoretical/numerical investigations of direct-acceleration of charged particle beams with laser beams. The successful student will gain the opportunity to work with and develop an understanding of relativistic particle beams, ultrafast lasers and nonlinear optics, and the interaction of EM fields with electron beams in a new regime.

The terahertz acceleration group (www.thzag.uk) is investigating acceleration of electron beams using ultrashort pulses of terahertz-frequency laser radiation; the terahertz pulses are produced through ultrafast non-linear optical process, while the interaction with particle beams is mediated with structures that control the electromagnetic propagation and polarisation. With recent successes in the acceleration of relativistic beams (Nature Photonics cover issue, December 2020) and laser streaking of 100 keV beams, the research will enter into a new era targeting very high-gradient acceleration for future large-scale facilities, and also for MeV electron diffraction.

The student will undertake theoretical and numerical investigations into a self-consistent ‘beam-loading’ model for the electron-electromagnetic interaction of structure-guided waves. The theory will be applied to the acceleration of both highly relativistic and lower-energy electron beams. The studentship will also undertake the development and experimental investigation of high-gradient THz-driven acceleration in dispersion-designed waveguide-like structures. The experimental research will make use of our ultrafast laser and electron-source facilities at the Cockcroft Institute, and high-energy particle accelerator facilities at Daresbury national laboratory.

The applicant will be expected to have a first or upper second-class degree in physics or other appropriate qualifications.

Education in particle accelerator physics or ultrafast lasers is not essential. A full graduate programme of training and development is provided by the Cockcroft Institute. The student will be based primarily at Lancaster University.

Potential applicants are encouraged to contact Professor Steven Jamison (s.jamison@lancaster.ac.uk) for more information.

Anticipated Start Date: October 2022 for 3.5 Years

Supervisor

Dr Elisabetta Boella

Description

The solar wind is a flux of plasma, e.g. ionised particles, constantly irradiated by the sun. Its existence was predicted by Eugen Parker in 1958 and later confirmed by several space missions. Since then, our insight into the dynamics of the solar wind has evolved tremendously, but many open questions remain. In particular, the identification of the physical mechanisms that regulate the energy budget of the solar wind is still a challenge.

Plasma in the solar wind is almost collisionless. Therefore, its evolution is mainly determined by the interaction between waves of different nature and the plasma particles. This PhD project is dedicated to exploring plasma waves and instabilities in the solar wind using theoretical frameworks and cutting-edge numerical simulations. This work will shed light on the microphysics governing the solar wind and its effects on macroscopic solar wind parameters. Simulations modelling solar wind conditions will allow identifying the physical processes that govern the solar wind energy balance. They will clarify the contribution of the different solar wind components to the energy budget. Furthermore, the theory and modelling effort will also provide crucial support to the interpretation of data from current space missions, such as Parker Solar Probe and Solar Orbiter. These spacecrafts are currently sampling the solar wind with an unprecedented level of detail. By using simulations and observations, the project is then expected to provide a new understanding of the energetics of the solar wind.

Through this project, the candidate will:

• Learn about plasma physics and space plasmas
• Contribute to and use massively parallel codes which the student will deploy and run on the most powerful supercomputers in the world
• Develop data analysis skills employing also forefront machine learning techniques

Funding is available on a competitive basis. Potential applicants are encouraged to contact Dr. Elisabetta Boella e.boella@lancaster.ac.uk for more information. They are also encouraged to send their applications via https://www.lancaster.ac.uk/physics/study/phd/#d.en.340732.

Supervisor

Dr Sergey Kafanov

In this project, the PhD student will work within the ULT group to investigate the behaviour of Micro-Electro-Mechanical (MEM) and Nano-Electro-Mechanical (NEM) resonators in the vacuum and superfluid ³He at world-record low temperatures. There is a growing demand for cooling micro and nano-electromechanical oscillators down to submillikelvin temperatures, and existing research indicates that ³He superfluid is the best available coolant to achieve this. The goals of the project are to understand and overcome existing cooling restrictions and to reach submillikelvin temperatures. Furthermore, MEM and NEM beams could be used to probe superfluid ³He at various sub-gap frequencies and length scales comparable to the coherence length of the condensate. This would have very far-reaching scientific and technological impacts.

In this project, the PhD student will work within the ULT group to study non-equilibrium phenomena in a well-known system with an established theoretical framework - superfluid 3He. Coherent condensates (or at least those to which we have experimental access) are fragile objects that only exist at the extremes of very low temperatures. We can study condensates over a wide range of conditions from the virtually zero-entropy zero-temperature quiescent state through to the regime where we have the destruction of coherence. It is "common knowledge" that when we move a scatterer through a superfluid, then at some critical velocity the superfluidity should catastrophically break down and return the system to the normal state. Recently, we have shown at Lancaster that this does not happen in superfluid 3He up to velocities well above the accepted Landau critical value. This was quite unexpected. Using for the first time the powerful combination of nuclear magnetic resonance with steady superflow in 3He at ultralow temperatures we aim to investigate several emergent phenomena such as quantum critical phase transitions between different superfluid phases.

Turbulence, we all know, is ubiquitous, impinging forcefully, not only on human activity but also overall nature on scales from the nuclear to the cosmological. That said, it is almost embarrassing that we still have no adequate theory of turbulence. This is where studies of quantum turbulence, the version of turbulence only occurring in superfluids, can play a part. Quantum turbulence is very different as there is no viscous dissipation since pure condensates do not support viscous forces. Nevertheless, the most fundamental difference arises from the phase coherence in the condensate that ensures that any vortices are singly quantised and thus identical. In consequence, we can regard such an ensemble as providing an ideal “atomic theory” of turbulence.

In this project, the student will work within the ULT group to study quantum turbulence and vortex pinning in superfluid 4He using torsional oscillator techniques. All earlier experiments on the generation of quantum turbulence by oscillating structures have used objects with convex surfaces; the flow around them is classically unstable at a low velocity, and the two expected transitions to turbulence are not distinguishable. In contrast, in this project the helium will be inside a pill-box that oscillates about its axis, thus eliminating all flow over convex surfaces. The two transitions should then be well separated and identifiable as characteristic increases in damping. The fundamental properties of the remanent vortices themselves will be studied, by investigating their pinning to microscopic protuberances.

Turbulence, we all know, is ubiquitous, impinging forcefully, not only on human activity but also overall nature on scales from the nuclear to the cosmological. That said, it is almost embarrassing that we still have no adequate theory of turbulence. This is where studies of the quantum turbulence, the version of turbulence only occurring in superfluids, can play a part. Quantum turbulence is very different as there is no viscous dissipation since pure condensates do not support viscous forces. Nevertheless, the most fundamental difference arises from the phase coherence in the condensate that ensures that any vortices are singly quantised and thus identical. In consequence, we can regard such an ensemble as providing an ideal “atomic theory” of turbulence.

In this project, the student will work within the ULT group to study numerically and experimentally visualization of quantum turbulence in superfluid 3He. We have pioneered the non-invasive detection of vortices by a surprisingly simple method which uses the Andreev reflection of quasiparticle excitations from the flow field circling each vortex. Our advanced vortex-detection techniques using mechanical oscillators provide knowledge of the turbulent behaviour that is simply not accessible in other systems. The measurements will be contrasted with computer simulations of moderately dense, three-dimensional, quasiclassical vortex tangles and the Andreev reflection of thermal quasiparticle excitations by these tangles. The research project will also address the question of how the Andreev reflectivities can distinguish quasiclassical and ultraquantum regimes of quantum turbulence, revealing their nature and signature properties

Supervisors: Yuri Pashkin, Ian Bailey, Edward Laird

One of the greatest challenges in physics is to identify the dark matter that makes up 80% of our galaxy’s mass. Among the leading candidates is a hypothetical particle called the axion. This is a well-motivated addition to the Standard Model but is very difficult to detect because it is predicted to interact feebly with ordinary matter. This project will develop quantum amplifiers in a new UK experiment that will search for axions.

If axions exist, then in a strong magnetic field they can decay into photons with frequencies proportional to the axion mass. However, the resulting electromagnetic signal is expected to be extremely weak – comparable to intrinsic quantum fluctuations, and weaker than thermal radiation except at the coldest accessible temperatures. This project aims to detect evidence of axions by developing and using superconducting amplifiers that can approach and ultimately exceed the standard quantum limit of detection sensitivity.

Lancaster Physics ranks among the highest-rated research departments in the UK. In the Low Temperature Physics and Quantum Nanotechnology groups, we carry out experiments in condensed matter physics and quantum electronics in some of the coldest and most isolated environments in the universe. We recruit highly motivated graduates in physics or related fields with curiosity, grit, and a passion for making new discoveries through experiment. We have a strong track record of high-profile publications by PhD students. We have access to excellent facilities for nanofabrication, electronics, and low-temperature measurement. These include:

• The state-of-the-art cleanroom of Lancaster’s Quantum Technology Centre.
• New cryogen-free dilution refrigerators optimised for high-speed quantum electronics.
• Extensive collaborations with low-temperature and particle physicists in Lancaster and beyond.

The student will work within the Quantum Sensors for the Hidden Sector Collaboration, which is an STFC-funded project to search for axions and axion-like particles (ALPs) using advanced quantum electronics and quantum measurement techniques. The collaboration works with the Axion Dark Matter Experiment (ADMX) in the USA, which currently leads the world in sensitivity to dark matter axions. We aim to develop a novel high-frequency axion target to be incorporated into the existing ADMX apparatus, as well as developing our own cutting-edge research instrumentation for axion and ALP research in the United Kingdom. The student will have the opportunity to develop research experience in a range of areas across quantum electronics, microwave electronics, cryogenics, magnetic field physics, quantum systems theory, and particle theory and phenomenology. They will join the collaboration as it embarks on this exciting new programme of inter-disciplinary fundamental research in the UK.

Further information:

• Low Temperature Physics at Lancaster
• The QSHS collaboration
• Professor Yuri Pashkin
• Dr Ian Bailey

Dr Edward Laird

Supervisor: Edward Laird

Magnetic resonance imaging (MRI) is a powerful and non-invasive technique for looking inside the human body. If we could make a microscope that works on the same principle, we would be able to do something that is presently impossible – to look inside cells, viruses, and potentially even individual molecules and identify the atoms from which they are made. Unfortunately, MRI machines cannot simply be made smaller, because as their radio antennas are shrunk they become less sensitive. For this reason, the resolution of conventional MRI is still far below that of other kinds of microscope.

To develop an MRI microscope, we need to develop a new kind of device that measures the same effect with much higher resolution. Such an approach is magnetic resonance force microscopy. In this technique, a tiny nano-magnet is attached to a delicate mechanical spring and positioned as close as possible to the specimen being measured. As the nuclei in the specimen precess, their magnetic field deflects the nano-magnet, thus creating a measurable signal.

To construct a microscope based on this principle is still a formidable challenge. For each nucleus in the specimen, the force exerted on the nano-magnet is roughly one zepto-Newton. We aim to detect such a force by using the lightest, most delicate spring that can be fabricated – a single carbon nanotube. This project will develop nanotube force sensors and the associated quantum electronics to measure them. The two central physics challenges are to attach a nano-magnet to a nanotube spring and to measure its tiny deflection. To overcome them, we seek highly motivated graduates in physics or related fields with curiosity, grit, and a passion for making new discoveries through experiment.

We have a strong track record of high-profile publications by PhD students. We have access to excellent facilities for nanofabrication, electronics, and low-temperature measurement. These include:

• The state-of-the-art cleanroom of Lancaster’s Quantum Technology Centre.
• New cryogen-free dilution refrigerators optimised for high-speed quantum electronics and equipped with ultra-sensitive superconducting amplifiers.
• Extensive collaborations with low-temperature and quantum physicists in Lancaster and beyond.

Within this project, you will work in the Low Temperature Physics and Quantum Nanotechnology groups at Lancaster. You will receive a thorough training, supported by state-of-the art equipment, in quantum electronics, low-temperature physics, nanofabrication, and scientific communication. Through your research in this project, you will have the opportunity to contribute to a physics-based technology with profound potential in materials science and biology.

Further information:

• Low Temperature Physics at Lancaster

Dr Edward Laird

Supervisor

Dr Dmitry Zmeev

Description

We will attempt to achieve the lowest temperature for any liquid. The project is concentrated around developing and demonstrating a new technique for cooling superfluid Helium-3. By utilising the nuclei of solid Helium-3 adsorbed on the surface of aerogel as a refrigerant in the adiabatic demagnetisation process, we will try and cool the superfluid to well below 100 microkelvins. Measuring such low temperatures is an arduous task. We will develop a method based on creating a Bose-Einstein Condensate of magnons within the superfluid and measurement its decay due to the very few thermal excitations remaining in the liquid. If successful, we will seek to apply the developed technique to cooling other systems, such as electrons in quantum devices, where lower temperature means longer coherence times.

Supervisor

Dr Viktor Tsepelin, Dr Jonathan Prance

Description

In this project, the PhD student will work within the Ultra Low Temperature group to design, build and investigate Superconducting Quantum Interference Device (SQUID) based noise thermometry for nanodevices. There is a huge demand for cooling micro and nano-sized samples down to submillikelvin temperatures and ULT currently holds world record on cooling electrons in nano samples. Cooling is accomplished either by submerging nano samples in liquid helium-3 or by the direct adiabatic demagnetization of nano samples. The outstanding challenge is to measure temperature accurately, reliably and fast. Unprecedented SQUID sensitivity will permit us developing a non-contact thermometer measuring magnetic noise raising from the oscillations of the electrons in the metallic nano samples. The amount of noise is temperature-dependent and can be calculated from the first principles, which allows the thermometer to be self-calibrated. We aim to use cross-correlation between SQUID two-channels to eliminate any noise from the SQUID amplifier thus making it operational down to submillikelvin temperatures (~50 microkelvins).

Supervisor

Professor Richard Haley

Description

In this project the PhD student will work as a member of the ULT group, fabricating and using superconducting nanomechanical resonators and other mechanical instruments to study superfluid 3He at ultra-low temperatures. Superfluid 3He is perhaps the most influential macroscopic quantum system in the laboratory, having frequent conceptual overlap with seemingly distant fields such as particle physics and cosmology. The aim is to show that this quantum liquid is two-dimensional at low temperatures and energies: any heat inserted flows along the edges of the liquid, never entering the bulk. This would redefine how we understand superfluids and large quantum systems in general. The work done will simultaneously technologically contribute towards using the superfluid as a dark matter detector in a large inter-university project in the UK.

Applicants are expected to have the equivalent of a first (1) or upper second (2.1) degree class in Physics or Astrophysics.

Funding is available on a competitive basis. Interested candidates should apply directly on this page stating the title of the project and the name of the supervisor.

Supervisor

Professor Richard Haley

Description

In this project the PhD student will work as a member of the QUEST-DMC team in Lancaster, based in the ULT laboratory. QUEST DMC is a four-university collaboration between Lancaster, Royal Holloway, Sussex, and Oxford using Quantum Enhanced Superfluid 3He as a Dark Matter detector. The PhD student will fabricate and use superconducting nanomechanical resonators, combined with quantum amplifiers provided by project collaborators, to build a superfluid 3He bolometer at ultra-low temperatures. The aim is to detect potential dark matter particles in the sub-GeV/c^2 mass range by recording their interactions with the superfluid. This work will simultaneously contribute towards fundamental studies of superfluid 3He, aimed at exploring the microstructure of the superfluid.

Applicants are expected to have the equivalent of a first (1) or upper second (2.1) degree class in Physics or Astrophysics.

Funding is available on a competitive basis. Interested candidates should apply directly on this page stating the title of the project and the name of the supervisor.

Aims

The research aims to apply ideas from condensed matter physics (quantum dots) to reach an understanding of ion channel conduction and selectivity based on the recently discovered phenomenon of ionic Coulomb blockade also allowing for the effect of dehydration. More generally, we aim to create a statistical theory of the permeation process taking explicit account of non-identical binding sites in the channel, the possibility of more than one ion at a binding site, and the consequences of ions being able to pass each other (i.e. non-single-file conduction).

Supervisors

• PVE McClintock
• A Stefanovska
• DG Luchinsky

Collaboration

• Biological and Life Sciences Department
• University of Warwick
• Rush University (Chicago)

Supervisor

Professor Aneta Stefanovska

Autism Spectrum Disorder (ASD) is a complex neurodevelopmental condition, characterised by persistent deficits in verbal and nonverbal communication as well as restricted and repetitive behaviour, interests and activities. Symptoms most commonly appear in children around the age of 3 or sometimes as early as 1--2 years old. The condition is relatively common, with a reported prevalence of around 1.5%. Current methods of diagnosing ASD rely purely on behavioural observations, and no physiological diagnostic test exits. Hence diagnosis often comes very late, even in adulthood, affecting the individual’s life chances. There is widespread interest in devising training or other remedial action to alleviate the symptoms and (hopefully) normalise the ASD child’s developmental pathway. But for this approach to be effective, there needs to a quantitative physiological method of identifying ASD and monitoring its development.

In a recent project in collaboration with Blackpool Victoria Hospital, we investigated the network couplings between brain waves recorded by electroencephalograph (EEG) in very young children, to seek possible differences between ASD children and normally developing children. We indeed found characteristic differences, and we believe that these can provide the basis of a novel instrument for the detection and quantitative assessment of ASD

The project will be carried out in collaboration with MyMind, a life science company based in Vienna, Austria. MyMind is developing an EEG-based neurofeedback device Brain Hero®, which is designed for convenient home-use and provides personalized therapy for ASD. The quantitative way of assessing the condition will be based on novel methods for data analysis developed at Lancaster and now available in the MODA toolbox https://github.com/luphysics/MODA.

This interdisciplinary enterprise will develop algorithms and software for Brain Hero®. Data being recorded in Switzerland, Portugal and Austria will be made available by the company. The PhD research will therefore involve theory, data analysis and computation.

The applicant will be expected to have a first or upper second-class degree in physics, applied mathematics, natural sciences, computational neuroscience, or biomedical engineering.

Interested candidates should contact Professor Aneta Stefanovska for further information.

Supervisor

Professor Aneta Stefanovska

Neurovascular coupling is essential for the functioning of the brain. Recent studies show that its efficiency changes with ageing or dementia. However, an efficient model of the interactions between the vasculature, astrocytes, and the neurones in the brain is still missing. Current models are mainly based on linear approaches and use a large number of differential equations to describe flows and concentrations of metabolites in relevant compartments of the brain. Such models are based on closed-system assumptions and focus on relationships between magnitudes of physical quantities involved. This project will investigate the potential advantages of models based on networks of phase oscillators that do not include any closed-system assumptions. Coupled nonautonomous phase oscillators will be used to represent the metabolic processes occurring within brain cells. Within the context of the model to be developed, the interaction between astrocytes and neurons and their changes with ageing and dementia will be investigated. The modelling will be tested by comparison with recent experimental studies in healthy subjects of different age, as well as with studies in subjects with Huntington’s and Alzheimer’s diseases.

The applicant will be expected to have a first or upper second-class degree in physics, applied mathematics, natural sciences, computational neuroscience, or biomedical engineering.

Interested candidates should contact Professor Aneta Stefanovska for further information.

Supervisor

Professor Aneta Stefanovska

By bringing together optics, modern computational facilities, the growing understanding of nonlinear oscillators and their mutual interactions, and wireless connectivity, it is planned to create a novel diagnostic instrument to determine the health of the human endothelium – the inner lining of all the blood vessels. In each individual, the endothelium occupies an area equal to a football pitch making it a major, albeit under-appreciated, organ of the body. It orchestrates the dynamics of blood circulation including the continuous distribution and exchange of nutrients and oxygen with all the cells of the body and the removal of waste products. Recently, the health state of the endothelium has been shown to play a crucial role in determining the severity of Covid-19. Although the health of the endothelium is of crucial importance for general health, it has been extremely difficult to measure up to now. So, the new “endotheliometer” is likely to be valuable to GPs and other health professionals.

This interdisciplinary project will be based on novel methods for data analysis developed at Lancaster now available in the MODA toolbox https://github.com/luphysics/MODA.

The applicant will be expected to have a first or upper second-class degree in physics, applied mathematics, natural sciences, or biomedical engineering.

Interested candidates should contact Professor Aneta Stefanovska for further information.

Supervisor

Professor Aneta Stefanovska

The famous Hodgkin-Huxley model describes an action potential in the axon of a neurone. It is an excellent example of how, by combining experiment and theory, physics can help resolve important questions in biology. It is arguably still the most realistic model of a living system. However, it assumes that the voltage across the membrane is constant, and to fulfil this condition in the experiments the voltage was clamped. In reality, however, the voltage continuously fluctuates in living cells, and the physics behind the fluctuations of the membrane potential therefore needs to be revisited. Recent advances in technology now enable the simultaneous recording of ionic concentrations, PH, cell volume, and production of the ATP that fuels the operation of ion pumps in the membrane.

This project aims to propose a new physics of the living cell by combining the experimental data obtained from simultaneous measurements, time-series analysis using novel methods developed at Lancaster now available in the MODA toolbox https://github.com/luphysics/MODA, and the new physics of nonautonomous dynamical systems. Phase coherence and synchronization will be analysed to assess stability of interactions, to characterise the normal and dysfunctional states a cell, and to build the new model.

The model will help integrate existing biological knowledge about individual components of the cell. It will provide unifying principles of functioning for both excitable and nonexecutable cells, and will thus pave new ways of modelling the brain in health and disease.

The applicant will be expected to have a first or upper second-class degree in physics, applied mathematics, natural sciences, or computational biology.

Interested candidates should contact Professor Aneta Stefanovska for further information

Supervisors

Professor Aneta Stefanovska, Physics

Dr Suzana Ilic, Environmental Science

Professor Peter McClintock, Physics

Occasionally, rogue waves – with wave heights much larger than those of their neighbours – appear on the ocean and can sometimes overwhelm even the largest vessels e.g. supertankers. Their origins are still a mystery, but a theory suggesting that their creation mechanism involves nonlinear interactions between smaller, conventional, usually wind-blown, surface waves is the best candidate to explain their formation. To seek experimental evidence in order to test this idea, experiments have been carried out in the Marintek wave basin in Trondheim, Norway. The result is a large volume of time series data, some of which shows clear evidence of rogue waves, but which has yet to be analysed. The PhD project is to analyse the Marintek data using state-of-the-art time-series analysis methods, many of which have been developed at Lancaster and are available in MODA toolbox https://github.com/luphysics/MODA in order to investigate the hydrodynamic conditions under which rogue waves are created. In particular, evidence will be sought for the growth of rogue waves through nonlinear mutual phase interactions between smaller waves. It is a challenging problem involving spatio-temporal dynamics, but it is clear that the results could be extremely important.

The applicant will be expected to have a first or upper second-class degree in physics, applied mathematics, or other appropriate qualification.

Interested candidates should contact Professor Aneta Stefanovska for further information.

Supervisor

Professor Aneta Stefanovska

Dr Dmitry Zmeev

Professor Peter McClintock

The 2-D electron system that can be created on the surface of superfluid He-4 has some remarkable properties. The electrons can move freely, without dissipation, over the interface between the vacuum above and a surface that is almost perfect. There is compelling evidence suggesting that, under the right conditions, this system exhibits chronotaxic dynamics – a phenomenon previously associated exclusively with biological systems.

The identification of this new class of non-autonomous oscillatory dynamical systems by the Lancaster group represented a major advance in the understanding of time-varying dynamics. These are oscillators whose characteristic frequencies vary in time, in contrast to e.g. the simple pendulum and many other familiar physical oscillators. Chronotaxic systems can be regarded as one manifestation of the thermodynamically open systems that abound in nature, and especially in biology. In collaboration with scientists at Riken in Japan, we have identified seemingly chronotaxic behaviour of the currents recorded for the 2-dimensional electron gas on the superfluid surface.

The aim of this PhD research project is to explain the physical origin of the oscillations of variable frequency observed in the experiments, and to provide a theoretical model of the experimental results, thus expanding and generalising the theory of chronotaxic non-autonomous dynamical systems.

The applicant will be expected to have a first or upper second-class degree in physics, applied mathematics, natural sciences, or engineering.

Interested candidates should contact Professor Aneta Stefanovska for further information.

Supervisor

Professor Aneta Stefanovska

Professor Peter McClintock

Dr Dmitri Luchinsky

For a billion years, life has been crucially dependent on ion channels for selective control of the fluxes of ions into and out of biological cells, with evolution fine-tuning each kind of channel to be optimal in its particular role. Very recently, humans have fabricated artificial channels and pores from solid state materials, aiming to emulate and extend many of the functions of biological channels in more robust formats. A whole new sub-nanoscale technology has started to develop, with applications to e.g. fuel cells, water desalination, gas and isotope separation, lithium extraction, DNA sequencing, water pumps, field effect ionic transistors, and “blue energy” harvesting.

Not surprisingly, artificial channels are still, in general, much less efficient than biological ones. For example, they are less selective for particular ionic species and the fluxes they pass tend to be smaller. They are difficult to design, partly because there is still no satisfactory general theory of how an ion permeates through a channel. Hence design usually relies on experiments and heavy-duty molecular dynamics simulations coupled with trial-and-error – which is slow, and therefore expensive, because the parameter space is huge.

We therefore propose a different approach, building on our 2015 discovery of Coulomb blockade in biological ion channels, on our new statistical physics theory of the ionic permeation process, and on our recent and ongoing numerical simulations of pores and channels in artificial membranes. There is probably a great deal to learn from how Nature has “designed” biological channels through evolution over hundreds of millions of years, so that biomimetic approaches are likely to be useful in understanding and designing artificial channels.

The aims of the project are to develop theory and numerical tools that enable the prediction and control of free energy landscapes, selectivity and conductivity of artificial nanodevices. These methods will be applied to the design and optimization of nano-pumps, nano-sensors, and energy harvesting nanodevices. It is expected that the successful applicant will use molecular dynamics and Brownian dynamics simulations to verify and validate the results obtained.

We are looking for a student with enthusiasm for theoretical physics and some prior experience of computational and numerical work.

Interested candidates should contact Professor Aneta Stefanovska for further information.

The project will develop advanced III-V nanowires on silicon and 2D materials by molecular beam epitaxy and explore the device applications in next-generation photodetectors, fully-functional silicon photonic circuits, ultra-fast nanoelectronics and spitronics.

Supervisor

Dr Quian Zhuang

Supervisors

Professor Manus Hayne, Department of Physics

Dr Peter Garraghan, School of Computing and Communications

Project

Computers are based on the von Neumann architecture in which the processing and memory unit are largely separated, requiring information to be shuffled to and fro, which is inefficient and creates a bottleneck. This particularly disadvantageous for activities that are memory intensive, such as artificial intelligence and machine learning.

An alternative is in-memory computing [1, 2], in which certain algorithms are performed within the memory unit. This is less flexible than the traditional von Neumann approach, but has huge potential in terms of computational time and energy saved for memory intensive tasks involving operations that are performed huge numbers of times. These could be common logical functions such as AND and OR, or matrix-vector multiplications which comprise between 70% and 90 % of the deep-learning operations in speech, language and vision recognition [2]. Many conventional and emerging memory technologies have been investigated for in-memory computing, such as SRAM, DRAM, flash and phase change memory and resistive RAM. However, memory technologies with very fast, low-energy switching, high endurance (and low disturb) are required to fulfil the potential of in-memory computing and compete with the conventional CMOS-based approach [1].

ULTRARAM™ is a patented Lancaster memory technology with a non-volatile storage time of at least 1000 years, an endurance in excess of 10 million program/erase cycles, non-destructive read, low disturb, a switching energy that is 100 times lower per unit area than DRAM, and intrinsic sub-ns switching speeds [3]. It has huge potential as a conventional memory, but also for in-memory computing.

The PhD project will be the first to investigate ULTRARAM™ for in-memory computing. The research will involve modelling (at different scales), and designing, fabricating and testing some simple ULTRARAM™ for in-memory computing circuits to show proof of principle, giving applicants the opportunity to explore and design the next generation of computing memory.

[1] ‘Memory devices and applications for in-memory computing’, A. Sebastian et al., Nature Nanotechnology, 15, 529 (2020) [Link]

[2] ‘In-memory Computing for AI Applications, E. Eleftheriou, 16^th International Conference on High-Performance and Embedded Architectures and Compilers, 18-20 January 2021 [YouTube]

[3] ‘ULTRARAM: a low-energy, high-endurance, compound-semiconductor memory on silicon’, P. D. Hodgson, D. Lane et al. [Link]

The project aims to develop high quality positioned quantum dot via droplet epitaxy and to explore the application in quantum optics.

Supervisor

Dr Quian Zhuang

Background

This is a joint proposal from two 50th Anniversary lecturers in Physics and the Materials Science Institute to establish a completely new paradigm for the bottom-up growth of complex nanostructured layers targeting the ultimate level of miniaturisation in data storage and processing.

The incoming student will enjoy a stimulating research environment joining a combined research team comprising two senior research associates, four PhD students and three Master’s students. The supervisors (BR and SJ) have an extremely strong track record in producing high impact publications, both as first authors and collaboratively. For example, a recent joint paper published in ACS Nano, 2017, 11 (3), pp 3404–3412 (IF 13.9) partly provides the platform on which this project is based. The student will have access to a wide range of experimental facilities including Lancaster’s molecular thin film fabrication capabilities and a suite of state-of-the-art scanning probe microscopes - housed in the newly commissioned £2m IsoLab ultra-low-noise facility - to explore the nanoscale topographical, mechanical and electrical transport properties in functional ultra-thin film structures. The student will be supported by a growing portfolio of funding including recent awards of £470k (BJR) and £122k (SPJ) from the EPSRC and Royal Society, respectively. We expect the student working on this project will publish multiple publications in leading journals, with at least one as the first author, and commensurate conference presentations.

Background

For most high-tech applications we make things better by making them smaller. By decreasing the gap between components on a computer processor we make calculations faster and by decreasing the size and separation of LED’s we make televisions thinner and more defined. Typically this has been achieved by ‘top-down’ lithographic approaches which still dominates industrial production but are hugely expensive, for example, it is estimated that for Intel to move from the 22nm to 14nm node for silicon chips the fabrication facility cost was at least $8.5 billion-plus another $2 billion-plus for research and development. The design of the circuit layout alone is estimated to cost more than $300 million.

Increasingly attention is shifting to radically different approaches for the fabrication of functional devices, whereby tailored materials comprising nanoscale building blocks are assembled ‘from the bottom up’ akin to the building of molecular-Lego.

This project

This PhD project is truly interdisciplinary sitting at the interface of synthetic chemistry, quantum physics and device engineering, with a significant cross-over into areas traditionally in the field of data science. The project aims to explore new methods for the scalable fabrication of ultrathin organic films with tailored quantum interference properties and tuneable electrode interactions. Traditionally, organic layers are formed from solution-phase deposition via techniques such as molecular self-assembly or Langmuir-Blodgett deposition. Here you will use newly established UHV capabilities in Physics to explore sublimation deposition, the direct transition from a solid to gas phase without passing through the intermediate liquid phase, of a range of tailored organic materials. Broadly the PhD project will:

• Develop a new capability to deposit and subsequently couple multiple layers of organic and inorganic materials onto the surface of a range of metal and 2D material substrates. This approach to multi-layer asymmetric chemical assembly is highly novel.
• The nanoscale properties of these films will be characterised in-situ in IsoLab using a suite of custom scanning probe microscopy systems to access nanoscale mechanical, electrical and topographical information with sub-molecular resolution.
• Understand the detailed physics and chemistry of these materials with advanced simulation methods performed on Lancaster’s High-End Computing (HEC) facility. Carried out concurrently to experiments, a simulation will be used to drive and inform ongoing experiments.

Supervisors

• Dr Benjamin Robinson
• Dr Sam Jarvis

The project targets the explanation of recently discovered extreme thermoelectric phenomena in nanostructures 2D (Van der Waals) materials such as graphene, and transition metal dichalcogenides and their heterostructures. A state-of-the-art experimental suite is available at Physics Department in collaboration with the National Graphene Institute to explore novel physical phenomena in these advanced materials.

Supervisor

Professor Oleg Kolosov

Supervisor

Dr Andy Marshall

Applications are invited for a research PhD in the Physics Department and Quantum Technology Centre at Lancaster University, UK. The project will focus on the study and development of novel infrared photodetectors aligned with the technology interests of ams.

The successful applicant will build on the group’s existing expertise in the growth, fabrication and characterisation of novel infrared optoelectronic materials and devices. They will gain state of the art experience in the growth of III-V materials by molecular beam epitaxy and the fabrication of commercially relevant photodetectors. Through comprehensive characterisation of the material and devices, detailed understanding will be gained and performance enhancements made.

The PhD candidate will join a thriving research group with fellow students and researchers sharing their knowledge in related fields. The Lancaster Physics department has a world leading research profile and longstanding record of ranking highly in UK research assessments.

This PhD project will be funded by ams Osram, a leading global sensor company. ams Osram will provide supervisory input and an application vision for the project. Their engagement will provide a pathway to rapid application of the project’s findings, making the student’s work highly relevant to future technologies which benefit people around the world. Working closely with an industrial partner will also give the successful applicant excellent professional development and enhance their career prospects.

Informal enquiries should be directed to Dr Andrew Marshall (a.r.marshall@lancaster.ac.uk).

To apply see https://ams.com/en/-/jobno-005707-austria

The discovery of graphene led to an explosion of interest in two dimensional (2D) materials. In recent years many other atomically-thin materials have been isolated and studied, with a wide range of different properties. Direct-gap semiconductors could revolutionise the optoelectronics industry, reducing the size, weight and power requirements of conventional devices such as displays, emitters, modulators and detectors, and also opening a new field in which the quantum properties of light are harnessed.

Atom-scale defects in 2D materials have been shown to efficiently emit quantum light, which is a sought-after resource for many applications in quantum information processing. Guiding the light emitted by these centres in useful directions, to make use of it, is an outstanding challenge that this project aims to address.

Photonic circuits that are compatible with 2D materials will be designed, fabrication and tested in the state-of-the-art facilities housed in Lancaster’s Quantum Technology Centre. You will be taught how to create the required structures using nanofabrication tools in the cleanroom, and the quantum nature of the light emitted will be assessed using a quantum electro-optics laboratory housed in Isolab.

Background reading:

[1] "Quantum information to the home" I. Choi, R. Young et al. New Journal of Physics 13, 063039 (2011) – see also goo.gl/HT1Ci and goo.gl/bg1Cd

[2] "Photonic crystals to enhance light extraction from 2D materials" Y. J. Noori et al. ACS Photonics 3, 2515 (2016)

[3] QOpto.com

[4] More about Isolab - https://www.lancaster.ac.uk/physics/isolab/

Supervisor

Professor R Young

Supervisor

Dr Ben Robinson

The Student: The successful PhD candidate will have a first degree in physics, materials science or a related area, they will explore new methods for the scalable fabrication of ultrathin organic films with tailored quantum interference properties and tuneable electrode interactions.

The Challenge: The global demand and utilisation of cooling is growing exponentially, releasing gigatonnes per annum of carbon into the atmosphere and accelerating climate change. This project will take an interdisciplinary approach to address the challenge of decarbonising cooling by investigating the potential of a new class of versatile, high-efficiency nanoscale thickness thermoelectric materials, for thermal energy management and recovery. By realising this function at the microscale, the mass deployment of this technology could have a major impact by displacing inefficient fossil-fuel-derived cooling.

The aim of the project: To understand how to improve the efficiency of nanostructured thermoelectric coolers (nano-TECs) based organic thin-films for thermal energy management and recovery and to make these devices a cost effective and attractive solution as a green and commercially viable technology.

Project Structure: The PhD student will be based in physics. They will be experimentally focused on Materials Development specifically assembly, optimisation and characterisation of organic and 2D material based nano-TEC thin films. To achieve this the PhD student will have access to dedicated state of the art laboratories for materials preparation and transfer and Lancaster’s world-class suite of scanning probe microscopy laboratories. Furthermore, the PhD student will work with colleagues from MSF under the guidance of Professor Richard Harper to understand, from a societal role, how nano-TECs may revolutionise small devices – such as local medicine or food cooling, and data farms, and to prepare a roadmap to understand the implications for these contexts and what it implies for the development and manufacture of nano-TECs

The Leverhulme Centre for Materials Social Futures: Lancaster University’s Leverhulme Doctoral Training Centre in Material Social Futures is a major strategic collaborative partnership between two of the university’s recently formed research Institutes – the Institute for Social Futures and the Material Science Institute. Based in the Physics Department you will be part of a growing team of PhDs who will examine how to create more sustainable and socially beneficial futures, and who will be trained to engage in diverse aspects of materials discovery and the analysis of social and economic structures to achieve these ends. In short, the goal of PhDs in Material Social Futures will be to help produce futures that people want and the world needs.

Please contact Ben Robinson b.j.robinson@lancaster.ac.uk for further information

Superconducting quantum circuits are commonly regarded as artificial atoms as they have discrete energy levels between which transitions are possible. High tunability of energy levels makes these structures promising for applications in quantum computing and quantum sensing. The large dipole moment of the artificial atoms makes it easy to couple them to electromagnetic modes of resonators in the microwave range. Currently, this coupling is widely used for interqubit interaction, lasing, etc.

In this project, we propose to study quantum systems in which superconducting artificial atoms will be coupled to surface acoustic wave (SAW) resonators. This is a novel area of experimental condensed matter physics, where Lancaster University can play a significant role. The speed of the surface acoustic waves is five orders of magnitude smaller than the speed of light, thus the devices based on SAW can find application as a memory element in quantum computing. What is more interesting, we are going to realise the strong coupling regime in which artificial atoms will emit spontaneously into the SAW resonator, i.e., ``acoustic laser'', and also demonstrate the ground quantum-mechanical state of the macroscopic mechanical resonator.

The student will learn the best from quantum physics, ultralow temperature cryogenics, microwave engineering and nanofabrication. This combination will provide the student with a set of highly desirable transferable skills.

We are going to submit a grant application within the QuantERA call (the deadline is 18 February 2019). This project is a collaboration between Lancaster, Glasgow, CNR (Italy) and the Institute of Physics of the Polish Academy of Science.

You are expected to have a strong interest and preferably knowledge in some of the fields:

• quantum physics, superconductivity and superfluidity, Josephson junction devices, Coulomb blockade, quantum optics and quantum information
• low-noise measurements and microwave engineering
• data acquisition using Python or MatLab
• cryogenic techniques
• nanofabrication

Supervisor

Yuri Pashkin

The unit of electric current, the ampere, one of the seven SI base units, has undergone a major revision recently. The previous definition, which was difficult to realise with high precision in practice, was replaced by a definition that is more intuitive and easier to implement. From May 2019, the ampere will be defined in terms of the fundamental constant, the elementary charge e, which was fixed for this purpose. This calls for the development of ultra-stable DC sources based on the highly controlled transfer of individual electrons that can be prototypes of the future DC standard.

Coulomb blockade devices offer the possibility of controlling charge transport in electrical circuits at the level of elementary charge and have the potential to produce DC with unprecedented accuracy. One of such promising devices is the so-called a SINIS single-electron transistor containing ultrasmall tunnel junctions made of superconductors and normal metals.

In this project, you will design, fabricate and measure the SINIS single-electron transistor to understand and eliminate error events in electron tunnelling. The project will be conducted in collaboration with Aalto University and the National Physical Laboratory. The fabrication will take place in the cleanroom of the Lancaster Quantum Technology Centre. The fabricated devices will be characterised in a dilution refrigerator at millikelvin temperatures.

You are expected to have a strong interest and preferably knowledge in some of the fields:

• quantum physics, superconductivity and superfluidity, Josephson junction devices, Coulomb blockade, quantum optics and quantum information
• low-noise measurements and microwave engineering
• data acquisition using Python or MatLab
• cryogenic techniques
• nanofabrication

Supervisor

Yuri Pashkin

The ability to cool materials to millikelvin temperatures has been the foundation of many breakthroughs in condensed matter physics and nanotechnology. At this frontier, quantum behaviour can be studied by making devices smaller and colder, increasing coherence across the system. The goal of this project is to apply a new technique – on-chip demagnetisation refrigeration – to reach temperatures below 1 millikelvin in nanoelectronic structures. This will open a new temperature range for nanoscale physics.

As experiments are pushed into the sub-millikelvin regime, it becomes increasingly difficult to measure and define the temperature of a material or device. The thermal coupling between various sub-systems in can be extremely small; for example, the electrons in the metal wires contacting an on-chip structure can be at a different temperature to the electrons in the chip, the phonons in the chip, and the apparatus that you are using to cool it. This situation calls for a variety of thermometry techniques, each suited to measuring the temperature of a different physical system. The thermometers must also have extremely low heat dissipation and excellent isolation from the room temperature environment. This project will include the development of new and existing thermometry techniques that are suitable for sub-millikelvin temperatures.

Devices will be produced in the Lancaster Quantum Technology Centre cleanroom, and by our collaborators. Experiments will be conducted using the cutting-edge facilities of the Ultralow Temperature Physics group at Lancaster.

You are expected to have a strong interest and preferably knowledge in:

• electrical measurements of nanoscale devices
• cryogenic techniques
• nanofabrication
• data acquisition using Python or MatLab

Supervisor

Jonathan Prance

The most important component for building superconducting circuits is the Josephson junction. It has recently been found that graphene, encapsulated in boron nitride and placed between superconducting contacts, can form high-quality Josephson junctions. What is more, these junctions can be controlled using local voltages, which is not normally possible. So far, graphene junctions have been used to build simple superconducting devices (SQUIDs and qubits) but their full potential has not been explored. This project aims to study new types of a superconducting circuit that exploit the special properties of graphene junctions. As well as learning about the physics of the superconducting proximity effect in graphene, the circuits will be used to demonstrate applications of these junctions in ultra-sensitive amplification and sensing (principally magnetic field sensing).

This project will make use of the recently completed IsoLab facility at Lancaster, which provides the “quiet” environment needed to study quantum devices and to assess their performance. IsoLab provides three highly-isolated laboratories for testing the electrical, mechanical and optical properties of materials and devices. One of the three laboratories is equipped with a dilution refrigerator capable of cooling samples below 10 milliKelvins. The refrigerator is housed in an electromagnetically shielded room and rests on a 50-tonne concrete block to provide vibration isolation. As well as studying new devices, this project will also include testing and development of the IsoLab environment.

A student working on this project will learn how to design and fabricate nanoelectronic devices and study their electrical characteristics at low temperature. The student will benefit from an ongoing collaboration between Lancaster and the National Graphene Institute in Manchester to study graphene/superconductor hybrid devices.

You are expected to have a strong interest and preferably knowledge in:

• electrical measurements of nanoscale devices
• cryogenic techniques
• nanofabrication
• data acquisition using Python or MatLab

Supervisor

Jonathan Prance

Supervisor

Dr Edward Laird

Jamming of satellite signals, by accident or design, is an increasing threat to transport infrastructure. In this joint project between Forsberg Services Ltd and Lancaster Physics Department, we are developing a device that will rapidly locate jammers based on measurements of their signals from different receiver locations.

Satellite navigation by GPS and its equivalents is a cornerstone of modern transport infrastructure. However, satellite navigation signals are easy to jam. Operators of ports and airports regularly encounter inadvertent jamming from leaky electronics and deliberate jamming due to criminal activity, and are also at risk of serious attacks by saboteurs or terrorists.

This studentship (for which we have applied for support via the CASE scheme) will devise reliable ways to locate jammers using a combination of physical insight and data processing. Your time will be divided between the Physics Department and Forsberg’s site in Heysham. This is an exciting opportunity to apply your knowledge of physics to an important challenge in engineering, and to work at the interface between the university and the technology industry.

Project Description

Lancaster University is offering a PhD project to study superconducting quantum devices, with a focus on Josephson parametric amplifiers operating at millikelvin temperatures. The start date is 1 October 2019.

Quantum technologies require the preparation, manipulation and readout of quantum states that are sensitive to noise and prone to decoherence. One of the most promising approaches is based on using superconducting circuits that benefit from extremely low dissipation and well-established fabrication process. The challenge in the field is handling quantum states with the utmost care and amplifying extremely weak signals using advanced instrumentation. Recent developments depend on the availability of cryogenic amplifiers with sufficient gain and bandwidth, and with an added noise level that is only limited by intrinsic quantum fluctuations. Existing semiconductor and superconducting amplifiers all suffer from compromises in one or more of these critical specifications.

The Josephson Travelling Wave Parametric Amplifier (JTWPA) (A.B. Zorin, Phys. Rev. Applied 6, 034006 (2016)) is predicted to outperform the existing versions of parametric amplifiers in gain, bandwidth and simplicity of construction. The JTWPA will be integrated with the single-Cooper-pair transistor to facilitate early uptake by the user community.

The project will be undertaken in the Lancaster Quantum Technology Centre. The work is experimental and an essential part of the project will be device fabrication using state-of-the-art nanofabrication facilities available in the LQTC cleanroom. The student will gain experience of working in a cleanroom environment and acquire practical skills in electron-beam and photolithography, thin-film deposition and plasma processing. They will be assisted by the experienced dedicated cleanroom technicians and academic staff who have the expertise and hands-on experience in nanofabrication. Device characterisation will be performed in a cryogen-free dilution refrigerator equipped with microwave measurement lines and cold amplifiers.

The Physics Department is a holder of Athena SWAN Silver award and JUNO Championship status and is strongly committed to fostering diversity within its community as a source of excellence, cultural enrichment, and social strength. We welcome those who would contribute to the further diversification of our department.

Supervisor

Professor Yuri Pashkin

Please contact Professor Yuri Pashkin y.pashkin@lancaster.ac.uk for any additional enquiries.

Supervisor

Dr Quian Zhuang

Description

This project aims to develop broadly tunable mid-infrared VCSEL devices and explore its use for interferometry. This will be achieved through the use of semiconductor type II cascade structures with an external cavity, to provide VCSEL with tenability of ~ 1 um. Precise tuning of the emitting wavelength of VCSEL pairs through self-heating phenomena will be explored to investigate the use in interferometry.

The project will be closely incorporated with MIRICO, a company dedicated in gas analysing based on laser interference induced by phase shift. The success of the project will provide a completely new technology for gas analysing, which can provide significantly improved accuracy, response time and compactness, with massively reduced cost. MIRICO will provide in-kind input, e.g. investigate the interferometry features from VCSEL pairs that commercially in the market and assess Lancaster VCSELs and their interferometry, and offer secondment opportunities for the student to develop and use their optical bench setup to assess Lancaster VCSEL. The student will be trained for the use of companies’ facilities and will be supervised by senior engineers from the company; the student will also learn about the management approaches of the companies, in particular with MIRICO which is experienced in managing EU and Innovate UK research projects. The student should also develop the skills in lecturing – he/she will be the key contact to present the research outcomes to the companies and to intake the feedback from companies to achieve the next milestone.

Also, there will be a good chance formulating a joint research proposal including Physics, LEC and MIRICO for a bid to the forthcoming UKRI research program aiming to tackle climate change and driving clean growth (focused on the theme of Clean Air). The PhD candidate will be in a consortium including physicists, environmental scientists and instrumental engineers if the bid is successful.

Temperature is a fundamentally important thermodynamic parameter. For life, the temperature range is markedly restricted by phase transitions in biomolecules, biomolecular assemblies and physiological environment limitations. Expanding these boundaries, an ability to reversibly freeze physiological processes making life dormant and to revive at will would be invaluable.

This PhD project that is a collaboration between Lancaster Physics and Biology and Life Sciences will identify, quantify and manage nanoscale, the physical and biological impact of cryo-induced changes. It will use the effects of low temperatures on life as a versatile biocompatible physical interrogation revealing novel principles of function of biological objects from molecular assemblies through to tissues.

You will study the nanoscale structure of systems quenched at variable stages of the cryo-process will be investigated via scanning probe nano-tomography, providing 3D nano-maps of key physicochemical properties – mechanical (affecting crystallisation), thermal (governing ice-nucleation), dielectric (water content) and spectrochemical (biomolecular nano-identification), developing a fundamental knowledge of low temperature influence on biosystems across diverse length scales.

Supervisor

Professor Oleg Kolosov

Majority of nanoscale materials and devices involve layered and patterned structures such as nanowires or nanopillars with dimensions ranging from ~ 10 nm to um. The properties, morphology and quality of multiple buried layers and interfaces are crucial for the development of novel devices, improving device performance and optimization of production processes. Unfortunately, the key active layers case hidden 10s to 1000s nm deep under the device's surface.

The PhD project will make a step-change offering a new widely applicable concept for fast and efficient 3D characterisation of nanomaterials and devices. This approach, pioneered at Lancaster in Kolosov’s group uses Ar ion beam targeted at the edge of the sample to create a perfectly flat oblique flat section with near-atomic flatness across all layers of interest. These are studied by the material sensitive scanning probe microscopy (SPM), revealing 3D morphology, composition, strain and crystalline quality via local physical properties –mechanical and piezoelectric moduli, nanoscale heat conductance, work function and electrical conductivity. This capability not existing before the Lancaster developments have huge potential in revolutionizing how we can explore and develop new nanoscale devices from microelectronics and lasers to biosensors.

Supervisor

Professor Oleg Kolosov

Industrial collaborators

Bruker LTD, LMA Ltd

The project aims to address the complex and currently rapidly worsening global problem of comfortable yet energy-efficient urban housing aggravated by the unprecedented growth of population density in metropolitan areas, with this project targeting both improving cities sustainability and reducing air pollution in the metropolitan areas. Residential and commercial structures consume up to 40% of electricity across the globe, with a significant fraction devoted to the heating, air conditioning and ventilation (HVAC). With windows (fenestration) estimated to provide around 60% heat entry (or loss), the material science aspect of this project targets novel concept of energy-efficient coatings (including external and internal coatings along with the fenestration).

The project employs an innovative strategy of tackling “invisible” but very active parts of the light spectrum. This is achieved by novel coatings with spectrally selective transmission, reflection and emissivity in visible (VIS) solar light, near-IR (NIR) parts of solar spectrum (carrying about 50% of solar heat energy) and at mid-infrared radiation (MIR) wavelengths (Fig.1), reducing heat inflow into internal areas, while preserving useful visible light helping to reduce internal illumination cost. Applied to windows and the wall coatings/paint, these will modulate the thermal heat outflow (for external surfaces) and reduce thermal heat inflow (for internal surfaces).

You will use the high-throughput materials discovery approaches to experimentally and theoretically screen the widest range of potential materials candidates - inorganic solid-state materials, the two-dimensional materials and organic additives, exploiting optical and plasmonic nature of thin layers and their internal nanostructure. Besides the films’ quality and devices’ performance, the fabrication method will constitute another crucial consideration, as manufacturing costs is an equally important parameter in many emerging technologies. To this end, the development of alternative deposition methods based on solution processing paradigms could provide a breakthrough in both cost and performance by marrying fabrication simplicity with high-throughput manufacturing, addressing the very large area deposition needs at industrial scale. A remarkable aspect of this approach is the accurate control over the electronic properties of solution-processed films through the simple physical blending of precursor solutions and soluble dopant molecules with successful coating prototypes engineered jointly with project industrial collaborators.

Supervisor

Professor Oleg Kolosov

The demand for new thermoelectric materials – those that generate electricity from waste heat – is vital to realising continued advances in information technologies, the built environment, aerospace and automotive industries. This project aims to develop a new family of materials, which exploit room temperature quantum interference effects, to maximise this potential and help fight climate change.

Small organic molecules (~3nm in length) are ideal candidates for thermoelectricity generation they are scalable, stable, and can be tuned to exhibit a high Seebeck coefficient. In this project, you will use Lancaster’s molecular thin film fabrication capabilities and a suite of state-of-the-art scanning probe microscopes to explore the physical processes of thermal and electrical transport in single-molecule junctions and ultra-thin organic films.

You will work closely with colleagues in Lancaster’s Quantum Technology Centre and theory division to design, fabricate and characterise efficient thermoelectric devices using direct chemical synthesis and also layer by layer assembly. The successful applicant will, amongst others, acquire skills in graphene and other 2D material fabrication and transfer, chemical self-assembly and scanning probe microscopy for nano-mechanical, -thermal and –electrical characterisation.

Supervisor

Dr Benjamin Robinson

Whereas graphene unique electron mobility and current densities - have been thoroughly investigated, its thermal properties, equally exceptional, are comparatively unexplored. In the thermal world, graphene is the highest thermal conductivity material, whereas another two-dimensional material (2DM), WSe2, possess the lowest cross-plane thermal conductance. This project combines efforts of two leading groups in 2DM's, for theoretical description in 2DM’s and advanced scanning probe microscopy (SPM) nano thermal characterisation of 2DM's to exploit these record-breaking thermal and electrical properties of 2DMs, where current and heat flows are confined into <100nm geometrical structures. Some recent preliminary studies at Lancaster of thermoelectric (TE) properties of graphene nanoconstrictions strongly suggest that the geometric dimensions of current and heat bearing pathways in the 2DMs lead to novel TE phenomena. The pioneering paper published by Professor Kolosov’s group in Nano Letters in 2018 had about 1,500 in just two months since its publication.

The project will target synthesis of 2DMs, manufacture nanostructures of individual 2DMs, heterostructures and their heterojunctions, measuring and mapping local nanoscale electronic transport in 2DMs nanoconstrictions and heterostructures from low to high current densities, using both lithography-defined electrodes Kelvin Probe/potential microscopy, scanning gate microscopy, local anodic oxidation. Exploration and analysis of the heat transport in 2DMs based nanostructures, its anisotropy, the layer number dependence, and the interaction with the substrate including encapsulation.

The project will explore the newly discovered paradigm of thermoelectricity to create a new platform for energy generation and heat management via nanoscale devices. The project is a follow-up of the large scale EU project QUANTIHEAT that finished at the end of 2017. For the materials and applications, we have the strong support of our key industrial collaborator on this project – Thales (France) who is extremely interested both in the portable thermoelectricity in their devices, as well as in thermal interface materials that can dissipate heat on RF and optoelectronics, preferably as flexible devices. For the characterisation side, Bruker has a major vested interest in the scientific instrumentation to explore nanoscale thermal and thermoelectric phenomena, acquiring in 2018 Anasys Instruments, a leading thermal probe microscopy company (where Professor Kolosov was a scientific advisor since 2006).

Please contact Professor Oleg Kolosov (o.kolosov@lancaster.ac.uk) for further information. For more general information about PhD study in Physics at Lancaster please contact our postgraduate admissions staff at py-pgadmiss@lancaster.ac.uk. You can also apply directly on this page stating the title of the project and the name of the supervisor.

Supervisors

Professor Oleg Kolosov

Dr Edward McCann

The incredible properties of 2D materials and vdW heterostructures provide a rich playground of exploration owing to their elegant quantum mechanical nature. We have recently shown that one class of 2D materials, TMDs (e.g. MoS₂ and WS₂), exhibit complex and identifiable variation in their optical emission which can be exploited as physically unclonable functions[1] for unbreakable quantum IDs. vdW heterostructures further increase this potential, where interlayer interactions are important in defining their physical properties locally. To gain a detailed understanding of this we need to glean information about the atomic uniqueness of the 2D material’s structure, both in single and multi-layers, and the defects which determine variations in physical properties. Our group has helped pioneer one of the few methods capable of imaging single atoms and chemical bonds[2]via advanced scanning probe microscopy (SPM) as shown in Fig. 1. SPM has the unique capability that it can simultaneously measure electronic and chemical properties, which promises a detailed understanding of 2D material structures.

This project will explore inter-layer interactions between vdW heterostructures of 2D materials and their use as atomically unique security devices. We will study how bilayer contact points in WS₂ and MoS₂ heterostructures, trapped material, and incorporation of graphene, boron nitride or organic layers affect their physical properties locally. The resulting hybrid structures will provide an exciting playground to develop a fundamental understanding of 2D material defects and inter-layer interactions. 2D material and vdW heterostructure properties will be studied and correlated with images of their detailed atomic and electronic structure (with resolution better than 0.1nm), using methods capable of imaging a single atom. Using these methods we will identify atomic scale defects and contact points in heterostructure materials that can be tuned to improve device performance and ultimately pioneer a new area of quantum security and technology.

The selected student will have the opportunity to become trained in a broad range of techniques to study a variety of 2D materials. This will involve advanced scanning probe microscopy methods capable of imaging single atoms and characterising nanoscale electronic and chemical properties, then correlating these with measured optical behaviour. This work will take place in world-leading facilities including Lancaster’s Quantum Technology Centre and the award winning IsoLab, providing some of the most advanced environments for characterisation in the world. You will work in a vibrant research group, whose research has been shortlisted for the Times Higher Education award for ‘STEM project of the year’ in 2019. You will also become highly trained in 2D material fabrication, Raman spectroscopy, photoluminescence, X-ray spectroscopy, clean room usage, device testing and use nano-fabrication tools to prepare devices for integration with embedded systems. Students are also expected to publish high impact journal publications, and present their work at international meetings and conferences, and will have the opportunity to work closely with our spin-out company, Quantum Base Ltd, around product development, providing excellent experience and prospects for future development and opportunities.

Please contact Dr Samuel Jarvis (s.jarvis@lancaster.ac.uk) for further information. For more general information about PhD study in Physics at Lancaster please contact our postgraduate admissions staff at py-pgadmiss@lancaster.ac.uk. You can also apply directly on this page stating the title of the project and the name of the supervisor.

Supervisor

Dr Samuel Jarvis

[1] T. McGrath et al., Appl. Phys. Rev. 6, 011303 (2019), Y. Cao et al., 2D Mater. 4, 045021 (2017)

[2] S. P. Jarvis et al., Nature Commun. 6, 8338 (2015), A. M. Sweetman et al., Nature Commun. 5, 3931 (2014)

The goal of this project is to develop new materials for use in sub-molecular scale electronics and as surface templates. This will be achieved by realising step-by-step on-surface synthesis of stable conjugated 1D and 2D molecular structures on electrically isolated surfaces. Due to their quantum mechanical nature, single molecules provide a fascinating playground for exploring and tuning electrical, optical and catalytic properties, with the promise of pioneering completely new fields of quantum technology.

At present, on-surface synthesis is reliant on the use of metal surfaces to catalyse reactions, which quench molecular electronic properties, severely limiting their broad applicability. You will instead exploit single-atom-catalysts (SACs) and recently developed atomic quantum clusters (AQCs) to activate covalent coupling reactions on non-conducting surfaces, where molecular density of states is largely unaffected by strong surface binding, enabling high tunability of electronic properties. We will use the unique chemical structure of AQCs to overcome catalyst poisoning and cluster formation, preparing samples across a range of cryogenic and elevated temperatures to control surface desorption and removal of reaction by-products, overcoming several known challenges for developing atomic scale molecular structures.

You will get the opportunity to become trained in a broad range of state-of-the-art techniques. This will include atomic force microscopy (AFM) facilities capable of imaging and characterising molecular and surface structure down to individual atoms and bonds and characterising nanoscale electronic and chemical properties. This work will take place in world-leading facilities including Lancaster’s Quantum Technology Centre and the award winning multimillion pound IsoLab, providing some of the most advanced environments for characterisation in the world.

You will work in a vibrant research group, whose research has been shortlisted for the Times Higher Education award for ‘STEM project of the year’ in 2019. You will also become highly trained in ultra-high vacuum equipment, molecular self-assembly, X-ray spectroscopy, scanning tunnelling microscopy and clean room usage. Students are also expected to publish high impact journal publications, and present their work at international meetings and conferences, with significant training providing excellent experience and prospects for future development and opportunities.

Please contact Dr Samuel Jarvis (s.jarvis@lancaster.ac.uk) for further information. For more general information about PhD study in Physics at Lancaster please contact our postgraduate admissions staff at py-pgadmiss@lancaster.ac.uk. You can also apply directly on this page stating the title of the project and the name of the supervisor.

Supervisor

Dr Samuel Jarvis

Supervisor: Edward Laird

Magnetic resonance imaging (MRI) is a powerful and non-invasive technique for looking inside the human body. If we could make a microscope that works on the same principle, we would be able to do something that is presently impossible – to look inside cells, viruses, and potentially even individual molecules and identify the atoms from which they are made. Unfortunately, MRI machines cannot simply be made smaller, because as their radio antennas are shrunk they become less sensitive. For this reason, the resolution of conventional MRI is still far below that of other kinds of microscope.

To develop an MRI microscope, we need to develop a new kind of device that measures the same effect with much higher resolution. Such an approach is magnetic resonance force microscopy. In this technique, a tiny nano-magnet is attached to a delicate mechanical spring and positioned as close as possible to the specimen being measured. As the nuclei in the specimen precess, their magnetic field deflects the nano-magnet, thus creating a measurable signal.

To construct a microscope based on this principle is still a formidable challenge. For each nucleus in the specimen, the force exerted on the nano-magnet is roughly one zepto-Newton. We aim to detect such a force by using the lightest, most delicate spring that can be fabricated – a single carbon nanotube. This project will develop nanotube force sensors and the associated quantum electronics to measure them. The two central physics challenges are to attach a nano-magnet to a nanotube spring and to measure its tiny deflection. To overcome them, we seek highly motivated graduates in physics or related fields with curiosity, grit, and a passion for making new discoveries through experiment.

We have a strong track record of high-profile publications by PhD students. We have access to excellent facilities for nanofabrication, electronics, and low-temperature measurement. These include:

• The state-of-the-art cleanroom of Lancaster’s Quantum Technology Centre.
• New cryogen-free dilution refrigerators optimised for high-speed quantum electronics and equipped with ultra-sensitive superconducting amplifiers.
• Extensive collaborations with low-temperature and quantum physicists in Lancaster and beyond.

Within this project, you will work in the Low Temperature Physics and Quantum Nanotechnology groups at Lancaster. You will receive a thorough training, supported by state-of-the art equipment, in quantum electronics, low-temperature physics, nanofabrication, and scientific communication. Through your research in this project, you will have the opportunity to contribute to a physics-based technology with profound potential in materials science and biology.

Further information:

• Low Temperature Physics at Lancaster
• Dr Edward Laird

Finding a fundamentally new way for data processing in the fastest and most energy-efficient manner is a frontier problem for applied physics and technology. The amount of data generated every second is so enormous that the heat produced by modern data centres has already become a serious limitation to further increase their performance. This heating is a result of the Ohmic dissipation of energy unavoidable in conventional electronics. At present, the data industry lacks a solution for this problem, which in future may contribute greatly to the global warming and energy crisis.

An emerging alternative approach is to employ spin waves (magnons) to realize waveform-based computation, which is free from electronic Joule heating. However, the present realization of this approach, called magnonics, uses electric currents to generate and modulate magnons. In the course of this PhD project, we will work towards the replacement of the current by light using antiferromagnetic materials, in which spins precess on a picosecond (one trillionth of a second) timescale and strongly coupled to electromagnetic waves [1]. Yet, the antiferromagnetic THz magnons remain practically unexplored.

To excite THz magnons we will use ultrashort strong electromagnetic fields produced either by table-top ultrafast lasers or by electron bunches at electron-beam facilities of Cockcroft Institute. We will push the driven spin dynamics into a strongly nonlinear regime required for practical applications such as quantum computation or magnetization switching [2]. We will investigate nonlinear interaction of intense and highly coherent magnons with an eye on reaching regimes of auto-oscillations, nonlinear frequency conversion and complete magnetization reversal.

This interdisciplinary project at the interface between magnetism and photonics offers training in ultrafast optics, THz and magneto-optical spectroscopies as well as in physics of magnetically ordered materials. Also, there will be opportunities for travel and experiments using THz free-electron laser facilities such as FELIX (Nijmegen, Netherlands) and TELBE (Dresden, Germany).

Interested candidates should contact Dr Rostislav Mikhaylovskiy for further information. You can also apply directly on this page stating the title of the project and the name of the supervisor. For more general information about PhD study in Physics at Lancaster please contact our postgraduate admissions staff at py-pgadmiss@lancaster.ac.uk.

Supervisor

Dr Rostislav Mikhaylovskiy

Supervisor

Neil Drummond

Description

In this project the successful applicant will use the CASINO quantum Monte Carlo software to model interacting charge carriers in two-dimensional semiconductors such as transition metal dichalcogenides. These materials are important candidates for novel optoelectronic devices, and excitonic charge-carrier complexes play a key role in the interaction of these materials with light. The project will build on earlier work on isolated charge-carrier complexes in monolayers and bilayers of these materials by examining multilayer systems and finite concentrations of charge carriers.

The project is computational in nature, and strong scientific programming skills are required (e.g., as evidenced by a significant undergraduate or Masters scientific programming project). It is hoped that the successful applicant will play an active role in maintaining and developing the CASINO code, including adapting it to exploit accelerators such as GPUs.

Supervisor

Neil Drummond

Description

In this project, quantum Monte Carlo and density functional theory methods will be used to understand the optical and excitonic properties of two-dimensional crystals of indium selenide and gallium selenide. The valence band exhibits a non-quadratic dispersion so that holes cannot be treated straightforwardly within an effective mass approximation. The effects of nonquadratic dispersion will be implemented within the variational quantum Monte Carlo method, requiring good programming skills.

Supervisor

Henning Schomerus

Description

Quantum systems can display robust features related to topological properties. These attain precise values that can only change in phase transitions where the states change their topological properties. While the scope of these effects is well understood for electronic and superconducting systems, a much richer range is accounted for photonic and in general bosonic systems. In these systems particles can be created and annihilated, which results in loss, gain, and nonlinearity. Recent years have seen a surge of activity to tailor these bosonic systems to their electronic counterparts, mostly by eliminating the mentioned differences. Going beyond these efforts, work of the supervisor and collaborators has demonstrated that topological physics extends beyond these mere analogies, leading to experimental demonstrations for laser, microwave resonator arrays, and polaritonic condensates.

What is missing is a detailed understanding of the actual scope of these extensions - how to systematically define the topological invariants, and classify systems in the manner achieved in the electronic context. This project tackles this question both generally, as well as practically by examining specific photonic and polaritonic model systems of experimental interest, and inquire how to increase their robustness for possible applications. This project develops both analytical skills in quantum mechanics as well as numerical modelling skills.

Supervisor

Henning Schomerus

Description

Quantum systems can encode information, but this information quickly becomes inaccessible if the associated degrees of freedom coupled with the environment. A key recent realization points towards a mechanism whereby quantum information can be localised by combining interactions with the generic disorder. This turns previously undesired artefacts into a highly valuable resource.

In previous work, we developed an efficient description of these so-called many-body localised systems based on a simple single-particle picture. This project aims to transfer this picture to a wider context, such as interacting spins or systems with additional internal degrees of freedom or dimensions. The project develops highly advanced numerical skills, such as DMRG, exact diagonalisation, and tensor network approaches. These will be applied to a range of model systems designed to yield conceptual insights that transfer to a wide range of systems.

Supervisor

Henning Schomerus

Description

The choice of geometry has dramatic consequences on the features of wave-optical systems. Two paradigms of this situation are optical microresonators with irregular shape whose classical ray dynamics connects to the notion of classical chaos, and metamaterials that acquire unconventional properties from sub-wavelength design features. This project explores the combination of these features with new a class of symmetries that involves the loss and gain in the system. The project aims to identify mechanisms for switching, mode guiding, and directed emission. The project develops both numerical skills for the modelling of optical and photonic systems, as well as analytical and conceptual skills for the design of novel structures that display new physical phenomena.

Supervisor

Janne Ruostekoski

Description

Cold atomic gases cooperatively coupled with light provide a rich strongly interacting quantum many-body system. The atoms and photons both are treated as quantum fields that can be solved using stochastic simulations and phenomenological approximate models. Long-range interactions between atoms occur through exchange of photons. The atoms can also similarly be considered of mediating interactions between photons. The aim of the project is to study such long-range dipole-dipole interactions between the atoms and their cooperative behaviour. The research can also be related to the effects of continuous quantum measurement processes and non-trivial topologies.

Background

One of the success stories of quantum physics is how individual quantum particles have been controlled and manipulated for quite some time. However, the realisation of a fully controllable, strongly interacting and coherent quantum system, consisting of many particles, is an outstanding challenge. A new frontier of quantum physics has recently emerged utilising photons strongly coupled to quantum atomic gases, such as Bose-Einstein condensates and atoms trapped in optical lattice potentials. Such systems can utilise quantum phenomena for higher precision measurements and for quantum information processing while the interactions between photons and atoms can be engineered and manipulated for applications in quantum technologies.

Supervisor

Janne Ruostekoski

Description

Understanding the behaviour of a collection of particles is a challenging problem in physics, in particular in quantum mechanics, where the interaction between a pair of constituents is not necessarily a sufficient guide to predict many-particle dynamics. In many areas of physics, such as in typical relativistic quantum field-theoretical, elementary particle physics or cosmological systems direct observations or controlled laboratory experiments may not be possible. Many dynamical effects involving the emergence of topological defects and textures are so complex that even numerical treatment becomes unfeasible for their accurate description. Ultracold atom systems have been discussed as candidates for experimentally accessible laboratory testing grounds for theories in other areas of physics. Symmetry breaking in a phase transition to an ordered phase provides an important example.

The project concerns of a study of ultracold atomic gases with spin degrees of freedom as a laboratory system for topological defects and textures that emulates, e.g., stability properties of field-theoretical vacuum states of particularly rich phenomenology, such as knotted solutions. The project combines in unique and ambitious ways interdisciplinary ideas from optical and atomic physics and modern quantum field theories for state engineering, exploiting their generic features.

Supervisor

Edward McCann

Description

The aim of this theoretical project is to model the electronic properties of surface states in rhombohedrally-stacked multilayer graphene which are unusual because their topological nature gives rise to flat, degenerate electronic bands near the Fermi level. Their origin can be understood by noting the similarity between the lattice of rhombohedral graphene and that of a one-dimensional chain with alternating bond strengths as described by the Su-Schrieffer-Heeger (SSH) model which describes a one-dimensional topological insulator. This means that two surface states in rhombohedral graphene (each of which is localised near one of the outer two graphene layers) are almost degenerate, giving flat bands fixed to the middle of the bulk band gap for a broad range of in-plane wavevectors. The aim of the project is to model their properties taking into account symmetry-breaking effects, developing both analytical skills in quantum mechanics as well as numerical modelling skills.

A fundamental question in theoretical physics is how quantum information gets scrambled in many-body quantum systems. Strongly-correlated many-body quantum systems are notoriously difficult to analyze. A recent breakthrough has allowed physicists to make progress by utilizing a new family of minimal models, called random quantum circuits, which capture universal signatures of chaos, but yet are analytical tractable since the details of the physical system are abandoned except for unitarity and locality.

This project aims to advance the understanding of many-body quantum chaos especially in the presence of symmetries, by studying observables like the growth of quantum entanglement, spectral form factor, and out-of-time-order correlator. This project develops transferable numerical skills and analytical skills when possible.

I will be a lecturer at the Lancaster University starting from September 2022. Please visit https://amoshmchan.wixsite.com/home and get in touch at amos.chan@princeton.edu

Supervisor

Janne Ruostekoski

Description

Background

The interaction of light with resonant scattering centres is increasing in importance, for both fundamental research and technological applications, as experimentalists realise a growing number of such systems. Together with ready access to massive computer clusters, this has created the interesting confluence that we now have both the motive and the opportunity to study strong light coupling by means of microscopic numerical simulations. Advances in nanofabrication now allow us to reach high sensitivities with longer coherence times and an enhanced optical thickness (which characterises the light-matter coupling) in miniaturised devices. This results in a cooperative response and strong light-mediated interactions between the excitations of the scattering centres that poses a theoretical challenge in many-body physics with the eventual goal of reaching the quantum regime.

3D solid-state media as advanced resonance optical devices have encountered fundamental problems due to photon loss and fabrication challenges. These are being replaced by 2D metasurfaces, providing realisations of ultrathin, lightweight flat lenses with unprecedented functionalities.

Project Outline

In this project, the student will theoretically analyse and numerically simulate the collective responses of 2D arrays of subwavelength-spaced resonant scattering centres. Together with the research group, they will develop methods for designing novel cooperative responses that can be utilised for optical manipulation and functionalities of ultrathin devices. By locally varying the properties of the system it is possible to build optical holograms and phenomena reminiscent of chirality that can be utilised for directed emission of light, as well as potentially for quantum devices, allowing the design of active optical media. The advantage of strong interactions is that the sensitivity of the optical devices is no longer limited by the resonance linewidth of the isolated scatterer, but by the collective resonance linewidth [1], which is potentially several times narrower. The project involves close collaboration with experimental effort to build such structures in thin semiconductor layers of AlAs and GaAs [2] or MoSe [3], in photonic crystal and silicon arrays.

The student will join a theory group studying cooperative optical phenomena in different physical systems and will gain experience in large-scale numerical simulations and high-performance computing. The co-supervisor will be performing experiments on these systems, providing guidance on the suitability of the models for laboratory realisations.

Supervisor Professor Janne Ruostekoski, Physics Dept, Lancaster, j.ruostekoski@lancaster.ac.uk

Co-supervisor Professor Rob Young, Physics Dept, Lancaster, r.j.young@lancaster.ac.uk

[1] S. D. Jenkins, J. Ruostekoski, N. Papasimakis, S. Savo, and N. I. Zheludev, Phys. Rev. Lett. 119, 053901 (2017). [2] G. Scuri et al., Phys. Rev. Lett. 120, 037402 (2018). [3] Patrick Back, Sina Zeytinoglu, Aroosa Ijaz, Martin Kroner, and Atac Imamoğlu, Phys. Rev. Lett. 120, 037401 (2018).