Current PhD Opportunities

Our PhDs are organised by our research groups. Click on the name of the subject area below for that groups current PhDs. For more information on each of these groups, please visit the Research section.

Observational Astrophysics

  • The next generation of Dark Energy measurements with supernovae

    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 projects are underway that aim to address this issue. The student will use a combination of archival data, new data from state-of-the art telescopes such as VLT, NTT and VISTA and simulated data to study statistical properties of supernovae as distance indicators. Based on these studies, he/she will help to optimise large surveys for cosmology that are planned with future telescopes and instruments, including LSST (the Large Synoptic Survey Telescope), ESA's Euclid mission and 4MOST (the 4meter Multi-Object Spectrograph Telescope).

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

  • The light that ended the dark ages: re-ionisation and the physics of the first galaxies

    Supervisor

    Dr David Sobral

    Description

    We finally have the state-of-the-art telescopes/instrumentation to peer back in time (to high redshift) and understand the nature and evolution of the first galaxies, stars and black holes, but also to study the Universe’s re-ionisation and the end of the dark ages. This project will allow the student to conduct and explore the largest surveys for very distant galaxies and pushing them to the highest look back times (z~8). She/he will benefit from our own state-of-the-art datasets that are now being obtained with the Hubble Space Telescope in space, ALMA and VLT in Chile. He/she will join the team that has discovered the most luminous Lyα emitters into the epoch of re-ionisation and the best evidence yet of sources similar to first generation stars or black holes, having the opportunity to study 100s of other similar sources for the first time with HST, VLT, Keck and WHT. The observations, analysis and modelling, which the student will push to z=7.7 for the first time with our pioneer HAWK-I/VLT survey, will provide the most stringent tests yet to state-of-the-art models of galaxy formation and evolution, of the first stars and black holes, and of re-ionisation itself.

    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.

  • Galaxy clusters in the Big Data era with LSST

    Supervisor

    Dr John Stott

    Description

    Galaxy clusters are the largest gravitationally bound objects in the Universe, consisting of 10s to 1000s of galaxies within a relatively small volume. They are used extensively as laboratories for galaxy evolution, as they contain galaxies that have experienced a similar environment and processes over many billions of years. They are also key cosmological indicators with the evolution of the number of galaxy clusters of a given mass being very sensitive to the Dark Matter content of the Universe. Because of their importance for both astrophysics and cosmology, it is desirable to obtain large, well-understood samples of galaxy clusters over a range of redshifts. The Large Synoptic Survey Telescope survey (LSST) is an imaging survey that will discover 10s of 1000s of new galaxy clusters, providing such a sample. It will image the entire Southern sky with an 8.4m telescope every few nights for 10 years, producing 200 petabytes of imaging data. This will be the state-of-the-art for optical surveys for many years to come.

    This data science-driven project aims to develop algorithms and machine learning code to identify large numbers of distant galaxy clusters within the LSST survey. The initial algorithms will be run on existing comparable, but smaller area surveys, and the early phase of LSST that will begin operation in 2019. The algorithms will be designed so that they can be scaled-up to deal efficiently with the full size of the main LSST survey. 

    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.

Space and Planetary Physics

  • Simulations of Plasma Transport in Jupiter’s Magnetosphere

    Supervisor

    Dr Chris Arridge

    Background

    The magnetosphere of Jupiter is populated by plasma that is mainly sourced from the volcanic satellite Io, initially forming a torus of plasma around Jupiter. This plasma cannot build up indefinitely and the majority of this plasma is transported outwards, ultimately to be ejected into the solar wind. Close to Jupiter (and Io) outward transport is generally accepted to be via an instability analogous to the Rayleigh-Taylor instability, but where gravity is replaced by the centrifugal force associated with rapid azimuthal plasma motion around the planet. This is known as the Centrifugal Interchange Instability and there is observational evidence for this process at both Jupiter and Saturn. However, this process is generally poorly understood, particularly in how mass and magnetic flux are “cycled”, how the transport process is regulated by the planet’s ionosphere, the importance of non-linear feedback effects, and the properties of unsteady/chaotic transport in the magnetosphere.

     This project

    The project is centred on building a new numerical model for plasma transport in the magnetosphere of Jupiter. The model will be a time-dependent 2D hybrid (kinetic ions, fluid electrons) model for the magnetosphere and a time-dependent 2D model of the ionosphere. These models will be coupled via the magnetic field of Jupiter. Once built and validated, the model will be used to investigate: 1) the physics of the transport process (examining the plasma motions and scales in the magnetosphere); 2) the importance of the ionosphere (its response to outward transport, the effect of latitudinally-varying ionospheric conductance, effects of variable ionospheric conductance); and 3) the effects of imperfect magnetosphere-ionosphere coupling.

    The Physics Department is a holder of an Athena SWAN Silver award and JUNO Championship status and is strongly committed to fostering diversity within its community as a source of excellence, cultural enrichment, and social strength. We welcome those who would contribute to the further diversification of our department. Lancaster University is one of the top 10 universities in the UK. The Physics Department was ranked 2nd in the UK for world-leading research in the most recent research excellence framework exercise (REF2014).

    Interested candidates should contact the supervisor 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. 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. Some experience of numerical simulations and/or computational physics is desirable but is not required.

    Funding Notes

    The PhD project is supported by a grant from the Royal Society and is for a duration of 4 years. Both UK and EU candidates are eligible.  Support includes full fees, a standard maintenance stipend and enhanced personal travel budget.

Experimental Particle Physics

PhD Projects on the ATLAS Experiment

  • Indirect New Physics searches in high precision measurements of CP violation in decays of Bs meson

    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.

  • Search for Supersymmetry particles in events with displaced vertices formed of lepton pairs in pp collisions at √s = 13 TeV with the ATLAS detector

    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.

  • Heavy Quarkonium

    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.

  • Investigating the Higgs

    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.

  • Searching for New Physics with Hadronic Jets

    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.

PhD Projects in Detector Development

  • Silicon pixel detector R&D for future particle physics experiments

    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.

PhD Projects on the Neutrino Programme

  • Neutrino interaction predictions and measurements using the T2K off-axis near detector

    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.

  • Searching for exotic phenomena at SNO+

    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.

  • SNO+ experiment

    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.  

  • T2K/Hyper-Kamiokande experiments

    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.

  • Precision neutrino physics at the MicroBooNE and SBND experiments

    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 potential 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.

  • Measurement of pion cross section on argon with the protoDUNE test beam experiment

    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 spent significant time at CERN and help with the installation and operation of the detector.

  • Precise cross-section measurements

    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.

Low Temperature Physics

  • Cooling nano-electromechanical systems to low temperatures

    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 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. 

  • Superfluid 3He far from equilibrium

    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.

  • Quantum turbulence and vortex pinning in superfluid 4He

    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. 

  • Visualisation of Quantum Turbulence via Andreev Reflection in superfluid 3He

    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

  • Miniature atomic clock based on endohedral fullerenes

    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.

    Funding for this project is for 3.5 years duration, with both UK and EU candidates eligible; support includes full fees and a standard maintenance stipend.  Potential candidates should contact Dr Laird without delay on e.a.laird@lancster.ac.uk

    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
  • Studying quantum motion using a vibrating carbon nanotube

    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 meoscopic 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 of 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. arXiv:1710.01920 (2017)
    • “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

Non-Linear and Biomedical Physics

  • Ionic Coulomb blockade, conduction and selectivity in biological ion channels

    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

    • P V E McClintock
    • A Stefanovska
    • D G Luchinsky

    Collaboration

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

Quantum Nanotechnology

  • Novel compound-semiconductor memory cells

    The ~$80bn pa memory market is almost entirely dominated by DRAM and Flash. Both have advantages and disadvantages that make them well suited for their roles in active memory and data storage respectively, but unusable in the other task. DRAM is fast, but data is erased when it is read (destructive read), and it has to be continually refreshed (DRAM is volatile). Flash is non-volatile and cheap, but intrinsically slow and requires high voltages that limit its lifetime (low endurance). An ultimate or ‘universal’ memory concept is one that combines the best features of both (non-volatile, low-voltage, non-destructive read, fast, cheap and high endurance), so suitable for either active memory or data storage. 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 non-destructive read that have the potential to fulfil all the requirements of universal memory (patent pending). The project will form part of this unique and exciting on-going research programme, with a particular focus on scaling memory cells to the nanoscale.

    Supervisor

    Professor Manus Hayne

  • Compound semiconductor nanowires and hybrids for advanced photonics and nanoelectronics

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

    Supervisor

    Dr Quian Zhuang

  • Site-controlled epitaxial quantum dots for quantum optics

    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

  • 3D architectures for molecular electronics – 3D-ME

    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 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 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 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, simulation will be used to drive and inform ongoing experiments.

    Supervisors

    • Dr Benjamin Robinson
    • Dr Sam Jarvis
  • Experimental exploration of thermal and electrical phenomena in nanostructures of Van der Waals materials.

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

    Supervisor

    Professor Oleg Kolosov

  • Fabrication and Characterization of Mid-infrared LEDs based on Pentanary Nanostructures using Digital Alloys

    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

  • Imperfect 2D materials for optical identification

    Supervisor

    Professor R Young

  • Charge Transport in High-Mobility Graphene Heterostructures

    Supervisor

    Dr Leonid Ponomarenko

  • Quantum phenomena in superconducting and hybrid devices

    Due to their unique properties, superconducting and hybrid superconducting/normal-metal devices allow control at the level of single charge or flux quantum, single photon and single phonon, and are promising for applications in sensing, metrology and quantum information processing. Examples of research projects include, but are not limited to:

    1. Charge pumping by nanoelectronic hybrid circuits
    2. Parametric amplification using Josephson circuits
    3. Detection of the quantum of mechanical motion by an artificial atom
    4. Interaction of surface acoustic waves with a superconducting artificial atom
    5. Probing quantum fluids with nanomechanical resonators.

    The work is experimental and involves nanofabrication of superconducting and hybrid circuits in the Quantum Technology Centre’s cleanroom and measurements at millikelvin temperatures in a dilution refrigerator. We work in close collaboration with the ULT group. We also collaborate with theorists, both at Lancaster and abroad.

    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

  • Generation and detection of single microwave photons using circuit QED

    Superconducting qubits can be used to detect and generate single photons in nearby microwave waveguides. The coupling of qubits to microwave circuits is known as circuit quantum electrodynamics (circuit QED) and it is analogous to the coupling of atoms to photon modes (cavity QED). The ability to control single microwave photons on-chip is essential for most superconducting quantum computing architectures. It also has potential uses in metrology and communications. The aim of this project is to fabricate circuit QED devices to study and improve, the efficiency of photon generation and detection.

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

    • quantum physics, superconductivity, 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

  • Ultralow temperatures in nanoelectronic devices

    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

  • 2D materials in low temperature, isolated environments

    Graphene and other 2D materials can be used to build coherent electronic devices such as Superconducting Quantum Interference Devices (SQUIDs) and Quantum dots. These devices can be used as sensors with the ability to detect single quanta of charge and magnetic flux. In order to reach this limit, it is necessary to cool the devices into the millikelvin regime and to isolate them from unwanted external perturbations including varying magnetic fields, electric fields and mechanical vibration. In this project, the recently completed IsoLab facility at Lancaster will provide the “quiet” environment to study quantum devices made from 2D materials and to assess their performance as sensors.

    IsoLab is a new facility that 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 millikelvin. 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 join 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

  • Nanostructured molecular materials on surfaces

    The Leverhulme centre for Materials Social Futures

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

    Lancaster University is one of the top 10 universities in the UK. The Physics Department was ranked 2nd in the UK for world-leading research in the most recent research excellence framework exercise (REF2014). The project will benefit from full access to the state-of-the-art facilities of Lancaster’s Materials Science Institute (http://www.lancaster.ac.uk/materials-science-institute/) and the new ultra-isolated environment lab (http://www.lancaster.ac.uk/physics/isolab/)

    Background

    We live in a world where technology is developing at a pace previously unseen. Individuals and institutions produce more and more information and use it in ever more subtle ways, for example, and this, in turn, is creating demand for ever smaller, more powerful computing devices. Manufacturers of these devices search for new materials that can revolutionise the storage of this information, making it smaller, cheaper, and more powerful. Nanotechnology offers one way forward to achieve these goals. Typically this has been achieved by ‘top-down’ lithographic approaches which still dominates industrial production but are hugely expensive. Now, increasingly, attention is shifting to a 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. Yet manufacturers, just like institutions and individuals, are not always fully aware of the ecological and social consequences that this demand for more data, more storage and new materials, might produce.  

    This project

    The successful PhD candidate will demonstrate an excellent academic record in physics, materials science or a related area, they will explore new methods for the scalable fabrication of ultrathin organic films with tailored quantum interference properties and tuneable electrode interactions. 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 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, simulation will be used to drive and inform ongoing experiments.

    The PhD project is for 3 years duration, with both UK and EU candidates eligible; support includes full fees, a standard maintenance stipend and enhanced personal travel budget.  In the first instance please contact Dr Benjamin Robinson (b.j.robinson@lancaster.ac.uk) or Dr Samuel Jarvis (samuel.jarvis@lancaster.ac.uk)  for enquiries.  You can also apply directly at http://www.lancaster.ac.uk/physics/study/phd/.  During the application process please state the title of this project and the name of the supervisor in your personal statement.  This PhD position is listed under PhD programmes in Physics.  A research proposal is not required for this position.  

    Supervisors

    Dr Benjamin Robinson (b.j.robinson@lancaster.ac.uk), Dr Samuel Jarvis (samuel.jarvis@lancaster.ac.uk)

  • PhD position in Superconducting Quantum Devices

    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 2018.

    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.

    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.

  • Electron Transport Studies in Ultra-High Quality Graphene Based Heterostructures.

    Project description:

    Graphene is one of the most fascinating materials ever discovered. It holds great potential for applications spanning nanoelectronics, sensors, composites and energy harvesting. Understanding its fundamental electronic properties is of paramount importance for making technological devices with novel functionalities [1]. The aim of this experimental project is to investigate fundamental aspects of electron transport in ultra-high quality graphene [2, 3] and related novel two-dimensional materials. To achieve this goal, the successful candidate will work with state-of-the-art graphene based devices and employ a wide range of experimental techniques available in the physics department of Lancaster University. These include atomic force microscopy, cryogenic experiments and high magnetic field techniques to name a few. The project would also involve nanofabrication work in the clean room of the Lancaster Quantum Technology Centre in close cooperation with the National Graphene Institute in Manchester.

    Requirements for the candidate. The candidate should be able to demonstrate good knowledge of solid state physics and have, or expect to obtain, Master degree in physics or natural sciences (not lower than UK second upper class or its international equivalent).

    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.

    Please contact Dr Leonid Ponomarenko (l.ponomarenko@lancaster.ac.uk) for further information.  You can also apply directly at http://www.lancaster.ac.uk/physics/postgraduate/how-to-apply/  stating the title of the project and Dr Leonid Ponomarenko as the supervisor in your Personal Statement.

    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

    Funding Notes

    The PhD starting date is 1 October and the project is supported by a grant from the Royal Society and is for a duration of 3 years. Both UK and EU candidates are eligible. Support includes full fees and a standard maintenance stipend.

    Supervisor:  Dr Leonid Ponomarenko

    1.            L. Britnell et al., Field-Effect Tunneling Transistor Based on Vertical Graphene Heterostructures. Science 335, 947(2012).

    2.            R. K. Kumar et al., High-temperature quantum oscillations caused by recurring Bloch states in graphene superlattices. Science 357, 181 (2017).

    3.            R. K. Kumar et al., Superballistic flow of viscous electron fluid through graphene constrictions. Nat. Phys. 13, 1182 (2017).

     

Condensed Matter Theory

  • Quantum Monte Carlo study of excitons and trions in doped transition metal dichalcogenide semiconductors

    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.

  • Optical properties of indium and gallium chalcogenides from first-principles calculations

    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.

  • Topological concepts for robust lasers and condensates

    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.

  • Statistical descriptions of interacting disordered quantum systems

    Supervisor

    Henning Schomerus

    Description

    Quantum systems can encode information, but this information quickly becomes inaccessible if the associated degrees of freedom coupled to 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.

  • Waveoptical control and dynamics in complex microresonator arrays and metamaterials

    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.

  • Long-range dipolar interactions in cold atom systems

    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. 

  • Numerical and theoretical studies of topological objects in ultracold atomic systems

    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.

  • Theoretical studies of nanophotonics of cold atoms in waveguides

    Supervisor

    Janne Ruostekoski

    Description

    In nanophotonics the goal is to enhance the interactions of light with matter by confining light. One-dimensional guided propagation light can be achieved in fibres and waveguides.

    Cold atoms, on the other hand, form a fascinating quantum medium for both fundamental physical phenomena as well as for applications in high-precision quantum technologies.

    Cold atoms experience long-range interactions that are induced by laser light, and in experiments they can even be confined inside fibres and waveguides. The waveguide enhances the coupling of light with the atoms, allowing for strong light-mediated dipole-dipole interactions between the atoms and a strong nonlinearity for light.

    The goal of the project is to theoretically and numerically study these interactions in order to understand, enhance, control and manipulate them. We will work closely with experimental groups providing guidance for their future experiments. Modelling the light transport in waveguides filled with atoms requires a combination of theory and numerical simulations. The topics that are relevant to the project include quantum mechanics, atom-light interactions, quantum optics and scientific computation.

    The Physics Department is 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.

    Please contact Prof Janne Ruostekoski (j.ruostekoski@lancaster.ac.uk  for any additional enquiries. You can also apply directly here stating the title of the project and the name of the supervisor.

    Funding Notes

    Funding for this project 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.

    Interested candidates should contact the supervisor 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.