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 the 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 LSST (the Large Synoptic Survey Telescope), 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 Prof 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 directly here stating the title of the project and the name of the supervisor.

Supervisor

Dr David Sobral

Description

One of the most exciting open problems in Astrophysics is understanding the nature and evolution of the very first galaxies, stars and black holes, but also how they changed the Universe as a whole and ended the dark ages. This PhD project will allow the student to conduct and explore the largest surveys for very distant galaxies (Lyman-α emitters) and push them to the highest look back times when the Universe was only 700 Myrs or less. The student will reduce, analyse and explore near-infrared photometric data in the COSMOS field from the recently concluded (100%) Y-NBS survey (PI: Sobral) on the Very Large Telescope in Chile, which had an allocation of 50 hours in excellent observing conditions. The Y-NBS survey is the widest ever conducted for distant bright Lyman-α sources, even more distant than the CR7 galaxy (Sobral et al. 2015) and the student is expected to find up to 20 new bright distant galaxies, along with 1000s of other lower redshift starburst galaxies and AGN. The student will also explore our state-of-the-art datasets that have just been obtained with the Hubble Space Telescope, ALMA and with other instruments on the VLT in Chile, to place the newly discovered galaxies into a wider context and test state-of-the-art models. The second part of the project will involve obtaining and exploring follow-up observations, including spectroscopy at a variety of wavelengths with the GTC (on-going program) in La Palma, in order to investigate the physics of the first galaxies. This will involve a close link with photo-ionisation and radiative transfer models and will provide some of the first measurements of the metallicity, ionisation parameters and other properties of early galaxies. The results will provide crucial new information to improve our currently limited understanding of the re-ionisation epoch and how distant bright galaxies may have played a crucial role in such a process.

Please contact Dr David Sobral 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 directly here stating the title of the project and the name of the supervisor.

Supervisor

Dr John Stott

Description

The majority of the stars in the Universe have formed in an active period of 7 to 11 billion years ago, an epoch known as ‘cosmic noon’. The reasons for this enhancement in star formation and its subsequent decline to the present day are not fully understood and so this is a major area of galaxy evolution research. Galaxies are governed by competing for physical processes: 1. the fuelling of star formation by gas accreted from the cosmic web and 2. the quenching of star formation by feedback from supernovae and supermassive black holes. Their environment also plays an important role with galaxies in dense clusters quenching at early times.

This PhD project will use spectroscopy to study the conditions of the gas within galaxies and the gas that surrounds them (the circumgalactic medium) in order to understand the balance of star formation fuelling and feedback at cosmic noon. The quasar sightline technique will be employed, which utilises the intense light from distance accreting supermassive black holes to observe the circumgalactic medium around galaxies along the line-of-sight to Earth. 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 directly here 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 fully-funded 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. 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 here stating the title of the project and the name of the supervisor.

Supervisor

Dr Brooke Simmons

Description

Disk galaxies with masses similar to that of the Milky Way are very common in the Universe, and they build up to their masses both by forming new stars in situ and by absorbing the stars from smaller satellite galaxies. Such “minor” (and even “micro”) mergers are likely responsible for a substantial amount of galaxy growth across the full population. The tidal streams from these interactions also remain coherent for billions of years and are extremely valuable as archaeological remnants of galactic formation processes. However, very little is understood about the effect of these minor interactions on galaxy evolution as a whole, because the unique properties of their tidal signatures present significant challenges to both observing them in real galaxies and modelling them with computer simulations.

With the latest generation of survey telescopes and high-resolution cosmological models, however, that is about to change. This project will, therefore, combine cutting-edge observational, theoretical and statistical approaches to understanding the growth of disk galaxies via mergers. A key aim is to develop a new analytical tool for quantitatively constraining the merger history of galaxies given their observed tidal features. This will involve hands-on work with large datasets as well as working with and writing code. This analysis package will be of significant interest to the astrophysical community, as will the project’s results applying that code to the latest data from current surveys such as the Dark Energy Survey and the Large Synoptic Survey Telescope commissioning surveys, which will commence during the term of this project.

The student will join multiple established, productive communities, such as the Galaxy Zoo and Horizon-AGN projects. They will likely also have the opportunity to gain hands-on observing experience at world-class telescopes.

This fully funded project would suit someone with some experience of writing code (Python, Java etc) and, more importantly, with a strong interest in developing that skill for use in statistical analysis of large datasets.

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. 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 here stating the title of the project and the name of the supervisor.

Supervisor

Dr David Sobral

Description

This project will allow the student to take part in a recent hunt for the most metal-poor stars up to the outskirts of the halo of our own Milky Way. Finding such extreme stars born in the early Universe but still shinning today allow us to unveil their nature. Most interestingly, very metal-poor stars allow us to become “stellar archaeologists” and understand the properties of the very first generation of stars that gave rise to the traces of heavy elements that led to their creation. Potentially, we may be able to find first-generation stars which may have survived until today. Finding and studying first-generation stars that may still be shinning in the halo of the Milky Way will be a major breakthrough in Astrophysics, not only to provide new tests and constraints to state-of-the-art models, but also because we will be able to study the generation of stars that literally invented chemistry and that is directly linked with our cosmic origins. The project will involve modelling of several observed and model stars to mimic observations and confront predictions with brand new data taken by us. Data have been taken using the INT telescope in La Palma and the CFHT telescope in Hawaii with narrow-band filters that capture a strong Calcium absorption feature in stars which becomes weaker for the most metal-poor stars. Our Lancaster-led data-set is the deepest ever done with this filter in the ultra-violet and allows us to see metal-poor stars individually up to the outskirts of the halo of our Milky Way.

Please contact Dr David Sobral 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 directly here stating the title of the project and the name of the supervisor.

Project Supervisor

Dr Konstantinos Dimopoulos

Description

Cosmic Inflation is a period of superluminal expansion of space just after the Big Bang. It is fixing the initial conditions of the Universe history, in that it makes the Universe large and uniform. Additionally, inflation generates quantum-mechanically the controlled violation of uniformity necessary for the build-up of structures such as galaxies and galactic clusters.

Inflation is under new light due to the recent cosmological data, such as the Planck CMB observations. Several families of inflationary models are now excluded, while new research on the favoured models overlaps with concerns over the stability of the electroweak vacuum (Higgs inflation) and the UV completion of gravity (R^2 inflation). The discovery of gravitational waves has ignited new interest in detecting primordial gravitational waves, quantum generated during inflation, which is a smoking gun for inflation theory, and motivates forthcoming missions (e.g. POLARBEAR).

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Project Supervisor

Dr Konstantinos Dimopoulos

Description

Observations suggest that the Universe at present is engaging anew in a period of late time inflation, determined by a mysterious substance called dark energy, which makes up about 70% of the density budget of the Universe today. Dark energy can be modelled similarly to primordial inflation, through a substance called quintessence.

Quintessential inflation is the effort to economically treat dark energy and primordial inflation in a common theoretical framework. As such, quintessential inflation connects not only with primordial inflation data but also with imminent future dark energy observations (e.g. EUCLID), which can provide information on early Universe physics at very high energies, well beyond the reach of Earth-based experiments. Moreover, quintessential inflation can exploit the famous scale mystery, whereby the scale of electroweak physics, which is explored in collider experiments such as the LHC, is roughly the geometric mean of the Planck energy scale, which is associated with gravity, and the dark energy scale. This implies that observations in the early and late Universe can be used to shed some light on particle physics phenomenology.

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Project Supervisor

Dr John McDonald

Description

The Standard Model of particle physics is unable to account for a range of cosmology and phenomenology, including inflation, the nature of dark matter, the nature of dark energy, the matter-antimatter asymmetry (baryon asymmetry) and the absence of strong CP violation. In this project, you will explore plausible extensions of the Standard Model that will attempt to simultaneously account for these issues.

Inflation can be achieved in conventional particle physics theories if the scalar particle driving inflation (the "inflation") is non-minimally coupled to gravity. You will study non-minimally coupled inflation models, in both conventional General Relativity (metric formulation) and in alternative frameworks (such as the Palantini formulation), which are rooted in plausible particle physics theories. You will study the cosmological evolution of the models from inflation through reheating to the present time. The possibility of accounting for dark matter, dark energy and the baryon asymmetry will be explored.

My present programme is focused on the QCD axion model, which can account for both inflation and dark matter, as well as providing a solution to the strong CP problem. With my present PhD student, Amy Lloyd-Stubbs, we are studying in detail the cosmological possibilities of the QCD axion model, including inflation, dark matter and dark energy. This has recently produced a first paper ["The KSVZ Axion Model with Quasi-Degenerate Minima: A Unified Model for Dark Matter and Dark Energy", A.Lloyd-Stubbs and J.McDonald, arXiv:1807.00778, to be published in Physical Review D.]

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Project Supervisor

Dr John McDonald

Description

Clockwork models of particle physics are based on a specific structure of explicit symmetry breaking which can generate particles with hierarchically small masses and interaction strengths. Such weakly coupled and low mass particles have a range of applications in cosmology, for example as stable or long-lived dark matter particles or weakly-coupled inflations to drive inflation. In this project, you will explore the possible applications of the Clockwork mechanism to cosmology and particle phenomenology. My recent work in this area has focused on its application to dark matter particles which produced by a process known as Freeze-In.

[Publications:``A Clockwork Higgs Portal Model for Freeze-In Dark Matter'', J.Kim and J.McDonald, arXiv:1709.04105 [hep-ph], Phys.Rev. D98 (2018) 023533; "Freeze-In Dark Matter from a sub-Higgs Mass Clockwork Sector via the Higgs Portal", J.Kim and J.McDonald, arXiv:1804.02661, to be published in Phys.Rev.D.]

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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.

Funding

The PhD starting date is 1 October 2019.  Funding is for 3.5 years and is available to citizens of the UK and the European Union.

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Supervisor

Professor Jim Wild

Description

Space weather describes the changing properties of near-Earth space, which influences the flow of electrical currents in this region, particularly within the Earth’s ionosphere and magnetosphere. Space weather results from solar magnetic activity, which waxes and wanes over the Sunspot cycle of 11 years, due to eruptions of electrically charged material from the Sun's outer atmosphere. Particularly severe space weather can affect ground-based, electrically conducting infrastructures such as power transmission systems, pipelines and railways. Ground-based networks are at risk because rapidly changing electrical currents in space, driven by space weather, cause rapid geomagnetic field changes on the ground. These magnetic changes give rise to electric fields in the Earth that cause geomagnetically induced currents (GIC) to flow to or from the Earth, through conducting networks, instead of in the more resistive ground. Railway infrastructure, safety-critical systems, and operations can be affected by induced electrical currents during extreme space weather. Studies of railway operations outside the UK have shown that induced and/or stray currents from the ground during strong magnetic storms result in increased numbers of signalling anomalies in track currents.  Meanwhile, induced direct current flowing in overhead line equipment has the potential to stop train movement.

In this project, you will investigate the level of GIC in UK rail infrastructure for the first time by undertaking a comparison of naturally-occurring geomagnetic activity with rail GIC measurements. The outcomes of this project will increase our understanding of the vulnerability of critical infrastructure to the space weather hazard.

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 Professor Jim Wild for further information.

Supervisor

Dr Adrian Grocott

Description

The Earth’s magnetosphere is largely controlled by the interaction between the solar wind and the Earth’s magnetic field. This interaction drives a large-scale electrical current circuit hundreds of thousands of km in size, and couples the magnetosphere to the ionised upper atmosphere - the ionosphere. These currents are also associated with a large-scale circulation of plasma and magnetic flux and together they dominate the dynamics of near-Earth space. In this project you will probe this interaction by developing novel analyses of Iridium constellation spacecraft observations of the current systems that link the magnetosphere and ionosphere (the Active Magnetosphere and Planetary Electrodynamics Response Experiment - AMPERE), and ground-based radar observations of the large-scale plasma circulation (using the Super Dual Auroral Radar Network - SuperDARN).

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 Adrian Grocott for further information.

Supervisor

Dr Sarah Badman

Description

We are entering a new era of understanding of giant planet environments thanks to the Juno mission at Jupiter, and concurrent Hubble Space Telescope images of Jupiter’s UV aurora. The combination of these measurements allow us to probe how the vast magnetosphere 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 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 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. Most recently, the Cassini-Huygens mission at Saturn/Titan, and the Juno mission at Jupiter have been providing data to answer these questions. The challenges of understanding these systems include processing and comparing 100s of GB of data; accounting for sampling, resolution and other instrumental biases; and inferring the state of processes in large-scale systems with limited spacecraft trajectories. In this project, the physics of Jupiter’s magnetosphere will be investigated using data from previous space missions (e.g., Galileo), numerical models, remote observations of the Aurora, and new data from Juno. The project will involve applying techniques from data science, such as machine learning, clustering, modelling, and statistical inference.

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

Professor Roger Jones

Description

The PhD will analyse new data from largest world’s 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 a 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 final conclusion on CP effects can be only done by performing both. In addition, 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 largest world’s 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 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 of the impact parameters of leptons.

Supervisor

Dr Vakhtang Kartvelishvili

Description

A heavy quark-antiquark bound state - has been an object of experimental and theoretical investigations over more than 40 years. Apart from an insight into the workings of Quantum Chromodynamics (QCD, the theory of strong interactions) quarkonium production at the LHC appears to be exceptionally useful in a wide variety of tasks, ranging from detector performance and trigger efficiency studies all the way to the determination of the Higgs boson couplings to fermions. Members of the Lancaster group have been instrumental in the vast majority of quarkonium studies performed in ATLAS.

Recently a variety of "new observables" in quarkonium production studies have been suggested, some of which - the production of vector quarkonium in association with a vector boson - have been performed in ATLAS. They showed a large excess over the expectation of theoretical calculations, thus injecting new interest into quarkonium physics. Other similar measurements are planned using the data from Run II of the LHC. A new PhD student will be expected to play a major role in one or more of these analyses.

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, there are other processes that 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

Professor Iain Bertram

Description

Currently, our best description of the theory of fundamental interactions of particles, the standard model of particle physics (SM), does not describe the Universe we live in. The SM cannot explain the observed matter-antimatter asymmetry of the Universe. This is before we consider the problem the 95% of the Universe that is made up of "dark" matter and energy of which the SM has nothing to say.

The LHC is currently the highest energy accelerator in the word, probing centre of mass energies up to 13 TeV. Jets of hadronic particles with transverse momenta of several TeV are produced in these collisions and are sensitive to the presence of physics beyond the SM. You will be searching for new particles that will appear as a peak in the mass spectrum or as a deviation from the predictions of the standard model (for example the angular distribution of the jets). These searches will be carried out by using jets that contain b-mesons (heavy quarks) and/or using multi-jet events to search for more esoteric particles.

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 for 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 in 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 a number of 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 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 Jonathan Gratus (Lancaster University)
Dr Hywel Owen (Manchester University)

Description

A studentship is available from Oct 2019 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 an understanding of the physics and design of future machines. A typical code may have to track 10¹⁰ 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.

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.

Closing Date

The position will remain open until filled.

Funding Note

The PhD anticipated starting date is 1 October 2019.  Funding is for 3.5 years and is available to citizens of the UK and the European Union (subject to residency status)

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

Prof 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. In addition, 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 a number of 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 in 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 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 Prof 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

Context

One of the most puzzling questions in plasma astrophysics regards the origin and evolution of magnetic fields starting from unmagnetized plasmas. A full explanation for the Universe magnetogenesis [1,2] or the spontaneous magnetic field creation in gamma-ray bursts, supernovae explosions, active galactic nuclei, etc [3] is still missing. The Biermann battery (BB) [4] and the Weibel (WI) [5] or current filamentation instability (CFI) [6] have often been invoked as possible mechanisms for magnetic field generation in unmagnetized plasmas. Previous works speculated that they could concur to create seed magnetic field [7,8,9], however how these fields evolve on long temporal and big spatial scales to magnitudes necessary for turbulent dynamo amplification [1,2] or equipartition values essential for shock dissipation [3] is still unknown.

The relevant physics is extremely rich, non-linear, multidimensional and multiscale, requiring modelling both the plasma microphysics and the relaxation processes. A kinetic approach must be adopted and Particle-In-Cell (PIC) codes [10], which can take full advantage of parallel High-Performance Computing resources, constitute the most effective tools. For astrophysical scenarios, where observations provide fewer details, the computational component has enhanced relevance, as a probe of the dynamics of these plasmas and as a tool to identify laboratory scenarios, which could enable direct and controlled probing of appropriately scaled astrophysical events. In fact, recently it has been realized that High Energy Density experiments leveraging high power laser facilities, such as OMEGA or NIF [11], could represent a new opportunity to study regimes very close to astrophysical conditions. First proof-of-principle (POF) experiments have been conducted [12], however, multidimensional features remain totally unexplored and until recently could not be appropriately investigated with numerical simulations due to the lack of appropriate tools and the extreme computing power required to resolve the plasma dynamics.

Leveraging the full power of PIC massively parallel simulations, the goal of this project is to gain knowledge on the formation and evolution of the magnetic field in unmagnetized plasmas. Astrophysical and laboratory scenarios will be investigated with the aim of identifying settings where the physics of relevance in astrophysical contexts can be reproduced by intense laser or beam-plasma interaction.

Objectives

In this project, a suite of PIC codes will be employed to shed light onto the processes of magnetic field generation and long-term evolution in unmagnetized plasmas. The project is organized along 3 challenges (C).

C1: development of a global multidimensional picture of the coupling between the micro and the macroscales of WI and CFI in electron-ion (e-p+) plasmas. A multidimensional picture of the magnetic field dynamics for longer times and realistic conditions is still missing. Exploring the instability for a wide range of parameters in multidimensional configurations will allow inferring the evolution of the fields, the saturation mechanism and the possible role of other physical processes, such as the turbulent dynamo, in amplifying the fields.

C2: identification of the laboratory conditions that will allow exploring experimentally the WI and the CFI. The possibility to investigate WI and CFI in the laboratory with intense lasers or particle beams will be explored resorting to a detailed comparison between the available parameters in the laboratory and the parameters explored in C1. This challenge will lead to the identification of the experimental conditions under which the scenarios studied in C1 can be reproduced in the laboratory, resorting to full-scale simulations. The latter will be based on already or near future available user facilities. It is thus expected that these results will lead to the proposal of experimental campaigns.

C3: analysis of the interplay between BB and WI in large systems. The role of the electron WI has been identified in kinetic simulations of the BB effect [9]. Furthermore, it has been found that a temperature gradient causes a temperature anisotropy, which scales as the inverse of the gradient and triggers the WI [9]. However, it has not been verified yet if this theoretical prediction could hold at longer spatial and temporal scales.

Methodology

At the core of the project is the ability to perform ab initio fully kinetic plasma simulations based on the PIC technique. PIC codes model plasmas as particles that interact self-consistently via the electromagnetic fields, which they produce. These models work at the most microscopic level and are therefore the ideal toolbox to address the questions raised in this proposal. The parallel PIC codes that will be made available for this project are: OSIRIS is a fully explicit PIC code [13]. It is a suitable tool to investigate electron physics. The code has demonstrated a high parallel efficiency up to 95%. ECsim is a new semi-implicit PIC code [14]. Since Maxwell and Newton equations are discretized using an implicit scheme in time, the code does not present any stability or accuracy issues, allowing for the use of coarser spatial and temporal discretization respect to OSIRIS, thus reducing the computational time. These properties are fundamental for the successful completion of the project. The code has demonstrated good scaling qualities, with excellent performances up to 1000 processors.

Supervisor

Dr Rostislav Mikhaylovskiy

Description

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 Cockroft 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). 

Funding

The PhD starting date is 1 October 2019.  Funding is for 3.5 years and is available to citizens of the UK and the European Union.

Interested candidates should contact Dr Rostislav Mikhaylovskiy for further information.

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. In order 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 in addition record the 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 rst 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 dierential 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 dicult 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 signicant 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 rst year, as well as the CI lectures, the student will learn the necessary dierential geometry and theory of distributions in order to understand the nature of the algorithm. The 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 wakeeld 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 eld prole 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 in order 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 (Hudderseld), McCall (Imperial)) which among other things will experimentally verify the existence of wave prole 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 first year, as well as undergoing the Cockcroft postgraduate training, the student will learn about spatially and temporally dispersive, time-dependent and inhomogeneous media. In addition, they would learn to run CST and run the proles already develop successfully by our collaboration. He or she will then be able to develop the time-dependent proles necessary for bunch shaping. These theoretical results could be veried 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 prole shaping in wire media: towards an experimental verication." Applied Sciences, Vol. 8, No. 8, 1276, 01.08.2018.

[2] Taylor Boyd, Jonathan Gratus, Paul Kinsler and Rosa Letizia \Customizing longitudinal electric eld proles 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 prole customisation using functional materials." Journal of Physics Communications, Vol. 1, No. 2, 025003, 06.09.2017.

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 all the way through to the regime where we have the complete 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 in excess of 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 clearly 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

Atomic clocks are among the most precise scientific instruments ever made and are key to advanced navigation, communication, and radar technologies. We are pursuing a new approach to create a clock that will fit on a chip. Instead of atomic vapours, we will use electron and nuclear spins in endohedral fullerene molecules – nature’s atom traps - whose energy levels offer an exquisitely stable frequency reference. To make this novel approach work, we must overcome a range of physics and engineering challenges, including detecting spin resonance from a small number of spins, identifying the energy levels involved, and miniaturizing the control electronics and magnet. The reward will be a completely new technology with a wide range of civilian and military uses. We are looking for a candidate who has a strong interest in applying quantum physics in new technology and is motivated to develop the new and demanding electronic measurement techniques that will be necessary.

References

• “Keeping Perfect Time with Caged Atoms”, K. Porfyrakis and E.A. Laird, IEEE Spectrum (Dec 2017, p34)
• “The spin resonance clock transition of the endohedral fullerene ¹⁵N@C₆₀”, R.T. Harding et al. Phys Rev Lett. 119 140801 (2017)

Supervisor

• Edward Laird

Funding

The PhD starting date is 1 October 2019.  Funding is for 3.5 years and is available to citizens of the UK and the European Union (subject to residency status)

To predict the behaviour of a small particle, for example, an electron moving through a molecule, it is essential to use the concept of quantum superposition – the particle may traverse a superposition of multiple paths simultaneously. Such superposition states have been beautifully demonstrated for photons, atoms, and molecules, but it is an exciting open question why larger objects do not show this behaviour.

We can address this question experimentally by studying the motion of mesoscopic objects containing millions of atoms. This project will make and measure vibrating carbon nanotubes, whose resonant frequencies are high enough that they can be cooled to their quantum ground state. We recently showed theoretically how to use an analogue of a grating interferometer to measure interference between different paths of motion. This project will use advanced cryogenic and nanofabrication technology at Lancaster to carry out the experiment.

References

• “Displacemon electromechanics: how to detect quantum interference in a nanomechanical resonator”. K.E. Khosla at al. Physical Review X 8 21052 (2018)
• “Resonant optomechanics with a vibrating carbon nanotube and a radio-frequency cavity”, N. Ares et al. Phys Rev Lett. 117 170801 (2016)

Supervisor

• 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 of cooling micro and nano-sized samples down to submillikelvin temperatures and ULT currently holds world record on cooling electrons in nanosamples. Cooling is accomplished either by submerging nanosamples in liquid helium-3 or by the direct adiabatic demagnetization of nanosamples. 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 nanosamples. The amount of noise is temperature dependent and can be calculated from the first principles, which allows the thermometer to be self-calibrated. Our aim is to use cross-correlation between SQUID two-channels in order to eliminate any noise from the SQUID amplifier thus making it operational down to submillikelvin temperatures (~50 microkelvins).

Aims

The aim of the research is 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)

An ultimate or ‘universal’ memory concept is one that combines the best features of DRAM and Flash, i.e. is non-volatile, low-voltage, non-destructively read, fast, cheap and high endurance. Implemented as RAM, such a memory would allow instantly on/off boot-free computers with unprecedented reductions in power consumption for mobile devices and computers. We have recently demonstrated the room-temperature operation of non-volatile, low-voltage, compound-semiconductor memory cells with a non-destructive read that has the potential to fulfil all the requirements of universal memory (patent pending). A project is currently available that will form part of this unique and exciting on-going research programme, with a particular focus on shrinking memory cells to the nanoscale.

Supervisor

Professor Manus Hayne

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

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 aim of the project is 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

A number of different approaches are currently being investigated for the fabrication of efficient Mid-infrared 2–5 µm light-emitting diodes LEDs. These devices are of interest because they could be used in instrumentation for environmental gas monitoring, medical imaging, free-space optical communications and other applications. However, the quantum efficiency of mid-infrared LEDs is significantly lower than those operating in the visible or near infrared. To date, different LEDs based on InAsSb/InAs or InSb/AlInSb, quantum wells, and quantum cascade structures have been produced to increase internal efficiency. Resonant cavity designs and flip-chip geometry can be used to increase optical extraction. Meanwhile, quantum dot structures have shown promising results and room temperature electroluminescence from LEDs containing InSb quantum dots has been obtained.

In this project, we aim to fabricate and characterize novel Mid-infrared LEDs based on 5-component digital alloy nanostructures grown by molecular beam epitaxy (MBE). The pentanary materials offer useful advantages to the device engineer because the presence of the fifth element in the alloy allows an additional degree of freedom for tailoring the performance of the device. For example, by fixing the band gap and the lattice constant, the alloy composition can be varied to independently adjust material properties, such as the refractive index or the spin-orbit split off band gap, for suppressing nonradiative Auger recombination and intervalence band absorption, which should ultimately improve device performance. Pentanary alloys can also be used with great effect as barriers and recently, strained type I quantum well LEDs and lasers containing pentanary AlInGaAsSb barriers have been demonstrated.

Supervisor

Professor A Krier

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 Leonid Ponomarenko

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 current sources based on the highly controlled transfer of individual electrons that can be prototypes of the future DC current 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 current 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 in order 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. The aim of this project is to study new types of 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

Vertical-cavity surface-emitting lasers (VCSELs) are very small (cheap) and efficient compound semiconductor laser diodes with established markets in optical datacoms and laser printing. In 2017 the launch of the iPhone X with its 3D sensing capabilities, based on 3 VCSEL dies, exploded the size of the VCSEL market to $330M, with predictions for a further 10-fold increase by 2023. So-called ‘eye-safe’ lasers that emit at >1400 nm are preferred for these applications, as the light is absorbed in the cornea, protecting the highly-sensitive retina. However, all production VCSELs, including those in smartphones, still lase at wavelengths <1000 nm. The aim of the project is to develop >1400 nm VCSELs and VCSEL arrays for consumer and LiDAR applications, based on our patented GaSb quantum ring technology. Strong interaction with industrial partners is expected.

The PhD starting date is 1 October 2019.  Funding is for 4 years and is available to citizens of the UK and the European Union (subject to residency status)

Supervisor

Professor Manus Hayne

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 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 Prof Yuri Pashkin (y.pashkin@lancaster.ac.uk  for any additional enquiries.)

Funding Notes

Funding for these projects is available to citizens of the European Union including the UK. Applications from non-EU citizens will be considered, provided the applicant has access to an alternative source of funding.

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.

In addition, 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

Prof 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

Prof Oleg Kolosov

Industrial collaborators

Bruker LTD, LMA Ltd.

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 Prof. 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 Prof. Kolosov was a scientific advisor since 2006).

Supervisors

Prof Oleg Kolosov

Dr Edward McCann

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 a number of 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

Prof Oleg Kolosov

The demand for new thermoelectric materials – those that generate electricity from waste heat – are vital to realising continued advances in information technologies, the built environment, aerospace and automotive industries. The aim of this project is 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) have been shown to be 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

Supervisor

Neil Drummond

Description

In this project quantum Monte Carlo methods will be used to investigate the behaviour of interacting charge carriers in heterostructures of two-dimensional transition-metal dichalcogenide semiconductors, and hence to understand the photoluminescence spectra of these fascinating materials.  In particular, the experimentally relevant situation in which there is a finite, low concentration of electrons will be investigated.  The project is computational in nature and good programming skills are highly desirable.

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 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

Applications are invited for a PhD studentship in theoretical cold atom physics, at the Department of Physics, Lancaster University. Cold atomic gases cooperatively coupled with light provide a rich strongly interacting quantum many-body system. The aim of the project is to study long-range dipole-dipole interactions between the atoms and their cooperative behaviour. The light-mediated interactions can also be engineered and manipulated for applications in quantum technologies and to simulate novel strongly interacting quantum systems, e.g., in the context of hybrid systems of atoms and nanophotonic structures. The project involves both numerical and analytic modelling is related to areas, such as quantum optics, optical physics and many-body physics. 

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.

Supervisor

Alessandro Romito

Description

Quantum measurement is a pillar of quantum mechanics. Recent technological make it possible to employ quantum measurements in a variety of protocols for precision measurement, quantum control, quantum feedback, and even quantum thermodynamics. With such a level of control, it is possible to use quantum measurements to induce geometric and topologically protected features in the quantum dynamics, as recently proposed.

The project aim is to set the theoretical basis for this measurement induced geometric dynamics. It will move from the formulation of a general theory that accounts for the effects of different and Hamiltonian dynamics to the proposal and modelling of experiments in electronic nanostructures. The student will make extensive use of theoretical tools of quantum mechanics and numerical simulation of quantum trajectories and will gain experience in the physics of electronic nanostructures.

Funding

The PhD starting date is 1 October 2019.  Funding is for 3.5 years and is available to citizens of the UK and the European Union.

Supervisor

Alessandro Romito

Description

Superconductors can exist in a phase that supports topologically protected excitations, Majorana zero modes, which can be controlled to perform certain quantum operations with exponentially good accuracy. The potential of Majorana zero modes for error-free quantum computation has triggered extensive experimental work, and experiments have successfully engineered Majorana zero modes in superconducting nanostructures. Due to their neutral electric charge, Majorana zero modes signatures are limited in electric probing but are expected to be more sensitive to energy probes.

The project aims at characterising the energetics and thermodynamic properties of driven Majorana based devices. The project will develop the theory of the topologically protected contribution to basic thermodynamic relations at the quantum level, and will then consider the implication of the results for quantum heat pumps and thermal machines. The student will work with the theory of topological superconductors in conjunction with quantum mechanics and thermodynamics. This will require the development of both analytical and numerical skills.

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 a 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  Prof. Janne Ruostekoski, Physics Dept, Lancaster, j.ruostekoski@lancaster.ac.uk

Co-supervisor  Prof. 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).