Research projects

This page is currently being updated for Projects available in 2020.

Applications should be submitted via the main University webpage. Apply Here

Dr Chris Ballance

1. Quantum computing with trapped ions

Trapped-ion devices have demonstrated, on a small number of qubits, all the building-blocks required to build a quantum computer with precision better than any competing technology. The aim of this project is to develop and utilise a world-class intermediate-scale quantum computer that, by virtue of high-fidelity any-qubit-to-any-qubit entangling gates along with low error rates, will operate at a performance level currently unachievable in any other architecture.

This is a challenging project which will push the limits of laser technology, quantum/classical control techniques, and quantum algorithm design.

The project will involve both experimental and theoretical work, including:
- building an apparatus that uses a newly developed type of trapped-ion qubit
- obtaining precision coherent control over individual atomic ions
- developing and applying new theoretical tools to understand and optimise many-qubit couplings

For more information, please contact Dr Chris Ballance

2. Fast, high-fidelity entanglement via optical phase control

Trapped-ion devices have demonstrated, on a small number of qubits, all the building-blocks required to build a quantum computer with precision better than any competing technology. However the speed of these devices, limited by the entangling gates, has not increased commensurately. The aim of this project is to change this by exploiting optical phase control to significantly speed up trapped-ion entangling gates whilst also removing several currently limiting fundamental sources of error.

In preliminary work, we have recently demonstrated the first high-speed entangling logic gates for trapped-ion qubits [Schafer et al., Nature 555, 75 (2018)]. We achieved a fidelity of 99.8% for a 1.6µs gate time, close to the highest reported two-qubit gate fidelities of 99.9%, but more than an order of magnitude faster. Over the course of this project we will extend this proof-of-concept technique to demonstrate the first high-speed control of multi-qubit registers.

The project will involve both experimental and theoretical work, including:

- developing and numerically modeling phase-controlled fast entangling gate dynamics
- building a new apparatus optimised for high-speed multi-qubit entangling gates
- sophisticated classical control techniques to precisely control the optical interaction phase of multi-qubit registers

For more information, please contact Dr Chris Ballance

Dr Patrick Baird

DPhil Research Opportunity on Ultra-High-Q Microresonators for Optical Frequency Comb Generation

Ultra-High-Q microresonators are extremely powerful devices that allow confining enormous amounts of light into tiny micron-scale mode volumes. This enables the observation of nonlinear optical effects at low threshold powers, making microresonators ideal components for future integrated photonic circuits and for the next generation of optical computing.

A key application that utilizes nonlinear optics in microresonators is the generation of optical frequency combs. Optical frequency combs have been first developed 15 years ago and have become ubiquitous tools for spectroscopy, precision metrology and optical clocks. In 2005 optical frequency combs have been awarded with the Nobel Prize in Physics. Microresonators have recently shown to be promising candidates for shrinking optical frequency comb generators into chip-based devices for out-of-the-lab use [1]. However, the underlying physics of optical comb generation in microresonators is far from being fully understood and fundamentally different from conventional mode-locked laser comb generators [2].

There is opportunity for an Oxford D.Phil student to join a recently established research team at the National Physical Laboratory (NPL) to work on microresonator-based frequency comb generation. At present there are several research projects available both on the applied side of frequency comb generation in microresonators as well as on the fundamental research side with the goal of understanding the physics of the underlying comb generation process.

NPL provides an ideal environment for research on optical frequency combs with an existing infrastructure of optical atomic clocks and conventional frequency combs that can be used for future experiments.

[1] Del'Haye, Optical frequency comb generation from a monolithic microresonator. Nature 450, 1214-1217 (2007)
[2] Kippenberg, Holzwarth, Diddams, Microresonator-Based Optical Frequency Combs. Science 332, 555-559 (2011)

For further information please contact either Dr Patrick Baird or Dr Pascal Del'Haye

Professor Andrea Cavalleri & Professor Paolo Radaelli

Breaking symmetry with light: ultra-fast ferroelectricity and magnetism from non-linear phononics

A collaboration between Prof. Paolo G. Radaelli and Prof. Andrea Cavalleri, who holds a joint appointment between
the Clarendon Laboratory and the Max Planck Institute for the Structure and Dynamics of Matter, (Hamburg).

Radaelli Cavalleri non linear graphic_0.png

Figure 1: schematic representation of non-linear photo-ferroicity. THz or far-IR ‘pump’ photons excite an IR-active mode (right), which is coherently coupled with a Raman mode (left). The rectified component of the Raman mode transiently generates ferromagnetism or ferroelectricity, which is probed coherently with a near-IR or visible light beam (top left).

The use of light to control the structural, electronic and magnetic properties of solids is emerging as one of the most exciting areas of condensed matter physics. One promising field of research, known as femto-magnetism, has developed from the early demonstration that magnetic ‘bits’ in certain materials can be ‘written’ at ultra-fast speeds with light in the visible or IR range [1]. More radically, it has been shown that fundamental materials properties such as superconductivity can be ‘switched on’ transiently under intense illumination [2]. Recently, the possibilities of manipulating materials by light have been greatly expanded by the demonstration of mode-selective optical control, whereby pumping a single infrared-active phonon mode results in a structural/electronic distortion along the coordinates of a second, anharmonically coupled Raman mode – a mechanism that was termed ‘nonlinear phononics’. Crucially, the Raman distortion is partially rectified, meaning that it oscillates around a different equilibrium position than in the absence of illumination. Very recently, it was realised that, under appropriate conditions, the rectified Raman distortion can transiently break the structural and/or magnetic symmetry of the crystal. Such symmetry breaking persist for a time corresponding to the carrier envelope of the pump, which can be less than a picosecond, and can give rise to the ultra-fast emergence of ferroic properties such as ferromagnetism and ferroelectricity. Through symmetry analysis and first-principle calculations, we have identified several promising ‘photo-ferroic’ materials that should display these effects, with potential applications in ultra-low-power information storage, ultra-fast electronics and many more.

This DPhil project will give the successful candidate the opportunity to pioneer this new field of research. Initial experiments on the candidate ‘photo-ferroic’ materials that we have already identified will be performed at the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg, Germany. As a mode-selective pump, we will employ coherent laser radiation in the THz or far-IR range with sub-ps carrier envelopes, while the transient emergence of the ferroic properties will be probed with second-harmonic generation (SHG) and/or Faraday rotation of near-infra-red light. Later on in the project, changes in the crystal and magnetic structures of the materials will be probed with X-rays at free electron laser sources such as the European XFEL in Hamburg. Meanwhile, the candidate will develop search strategies for new classes of ‘photo-ferroic’ materials, based on symmetry and density functional theory calculations. He/she will develop the materials specifications in collaborations with crystal growers in Oxford and elsewhere, and will be involved hands on in all aspects of the design and realisation of the experiments and the data analysis.

The experimental part of this project will be predominantly based in Hamburg, so it is essential for the candidate to be willing and able to be based in Germany for extended periods during the DPhil.

[1] Femtomagnetism: Magnetism in step with light. Uwe Bovensiepen, Nature Physics 5, 461 - 463 (2009)
[2] See for example M. Mitrano,et al., ‘Possible light-induced superconductivity in K3C60 at high temperature’, Nature, 530, 461–464 (2016)
[3] Nonlinear phononics as an ultrafast route to lattice control, M. Först et. al., Nature Physics, 7, 854–856 (2011)

For further information please contact either Prof. Andrea Cavalleri or Prof. Paolo Radaelli

Professor Christopher Foot

1. Optical lattice clocks for fundamental physics and redefinition of the second

This is an experimental project, working with some of the UK’s best atomic clocks at the National Physical Laboratory. The clocks are based on strontium atoms, which are laser-cooled to a temperature of 1 µK, and then trapped in an optical-lattice dipole trap. The trapped atoms are probed using an ultra-stable clock laser, which is tuned in frequency to address a narrow optical transition at 429 THz. By measuring whether the clock laser excites the atoms or not, we can steer the laser to “tick” at a rate matching the narrow atomic transition frequency. Following this procedure, the clock laser can measure the passage of time to 18 digits of precision – enough to resolve the gravitational redshift from a change in height of just a few cm on the surface of the earth.

Already optical lattice clocks reach fractional frequency uncertainties and instabilities more than 100 times lower than the best caesium primary frequency standards. As a result, optical lattice clocks are a likely candidate for a future redefinition of the SI second. However, before such a redefinition, it must be shown that these systems can be engineered to run reliably, and that frequencies derived from such clocks are reproducible. We achieve this through real-time comparison of NPL’s clocks with others across Europe via optical fibre links, and across the globe via satellites including the soon-to-be-operational Atomic Clock Ensemble in Space (ACES). These ultra-precise clock-clock comparisons also provide valuable insight into many open problems in fundamental physics, underpinning the hunt for dark matter, tests for violations of relativity, and constraints on possible variations in fundamental constants. To extend the reach of clocks towards new applications, new techniques must be developed to overcome the current limitations on clock performance. This effort will be the focus of the current PhD placement, for instance by exploring how quantum entanglement can be leveraged to supress frequency instability arising from quantum projection noise by engineering ‘spin-squeezed’ states.


For more information, please contact Dr Rachel Godun or Prof. Chris Foot

2. Experiments with ultracold atoms and Bose-Einstein condensates

Professor Foot’s research group investigates the fascinating properties on ultracold quantum gases at temperatures of a few tens of nanokelvin. Samples are produced using laser light to cool atoms from room temperature and then confining them in a magnetic trap where evaporation leads to further cooling. These processes increase the phase-space density by many orders of magnitude to reach quantum degeneracy (Bose-Einstein condensate for atoms with integer spin). The research group in Oxford has pioneered new methods of trapping ultracold atoms using a combination of radiofrequency and static magnetic fields that is a very powerful tool for probing 2D quantum systems.

Research on `Investigating non-equilibrium physics and universality using two-dimensional quantum gases’ is funded by a new EPSRC grant [1]. Coherent splitting and matter-wave interference techniques enable comprehensive read out the quantum information from these systems to study fundamental questions such as how an isolated quantum system evolves towards equilibrium (or quasi-equilibrium states). We are working with theoretical colleagues to make detailed comparison with quantum statistical mechanics. Understanding the fundamental quantum physics of many-body system has important implications for quantum devices and technology based on them.

Future research directions include experiments on weak quantum measurements (sometimes called quantum non-demolition) on atoms in double-well potentials (bosonic Josephson junctions), squeezed states of the atoms and extensions to quantum gases that are a mixture of multiple species such a rubidium and strontium atoms.


For more information, please contact Prof. Chris Foot

3. Development of cold-atom sources for quantum technologies

This project is suitable for those with an interest in developing new apparatus that will be applied to practical devices. We have developed a compact source of cold rubidium atoms based on a novel (patented) design of magneto-optical trap and we are collaborating with a laser company based in Scotland (M Squared Lasers) to commercialise this work. In this project we will develop a compact source of laser-cooled strontium atoms working with that company and other interested parties. Strontium requires a considerably different approach to that used for rubidium and developing the experimental methods into a robust and reliable system is the primary task.

We anticipate that there will be considerable demand for sources of cold strontium since they are necessary for clocks that use atoms in optical lattices (strontium clocks are currently the world-leading technology), matter-wave interferometers (for which one of the strontium isotopes is very suitable), as well as more fundamental research work on ultracold molecules and quantum gases. In summary, strontium has considerable advantages for quantum technology but it is not (yet) used so widely as rubidium because it requires more complicated apparatus. The technical issues will be addressed in this project and the cold-atom source will be demonstrated by building a matter-wave interferometer. Collaborations with other research teams to demonstrate other applications are likely.

It is expected that this project will be fully supported by a studentship for 4 years.

For more information, please contact Prof. Chris Foot

4. Next-generation cold-atom compact atomic clocks

EPSRC iCASE Oxford DPhil studentship in collaboration with the National Physical Laboratory

There is an opportunity for a DPhil candidate to join the miniature atomic clocks research team at the National Physical Laboratory (NPL) and become engaged in new leading-edge science developing compact cold-atom-based atomic clock systems. The experiment would be based at NPL, but with time also in the Clarendon Laboratory for graduate classes and Oxford seminars / colloquia.

NPL looks to develop novel atom cooling and interrogation schemes for cold atom high-stability frequency references within a compact form factor (< 800 cm3 volume). Existing compact microwave atomic clock systems employ frequency-modulated laser diodes to probe thermal atoms confined in small glass vapour cells using e.g. coherent population trapping (CPT) spectroscopy whereby the atoms are placed in quantum superposition states. These systems can be made to be very compact (< 17 cm3 volume), but the use of thermal atoms creates limitations in the frequency stability, as the linewidth of the detected frequency reference signal is broadened due to atomic collisions. By laser cooling the atoms, these collisions are minimised and the Q factor of the frequency reference signal can be greatly enhanced, offering high-performance atomic clocks.

Compact high-stability / high-accuracy clocks are needed for future safety-critical national infrastructure, aerospace, transport, power grid management, high-speed financial transactions and 5G telecommunications platforms, with a view to providing satellite navigation-independent timing references and synchronisation for high-volume data transfer.

For more information, please contact Prof. Chris Foot or Prof. Patrick Gill

5. Mini-fountain cold atom clock

EPSRC iCASE Oxford DPhil studentship in collaboration with the National Physical Laboratory, intended for EEA applicants.

The digital infrastructure and economy we rely on as society requires wide access to reliable and accurate timing signals synchronized to robust and largely autonomous timescales. The aim of this project is to build a prototype of a small footprint cold-atom frequency standard (clock) with short- and long-term stability enabling disciplining a local timescale to a residual deviation from UTC time smaller than a nanosecond over several weeks. Once fully developed, the mini-fountain clock is expected to find commercial applications in telecommunication, research facilities and defence. A planned novel compact optical system could also be a stand-alone product for applications in atomic physics experiments, including matter-wave interferometers.

The key subsystems of the clock to be developed include: a miniaturised fountain physics package, a novel optical bench, and electronics for control and data acquisition. The PhD candidate will have the opportunity to work on all aspects of an atomic physics experiment, such as ultra-high vacuum, narrowband lasers, microwave electronics, automated data acquisition, advanced statistical analysis and more. New research results (e.g. on cold atom detection and all-fibre optics) will be published in applied physics journals and presented at international conferences.

A systems engineering approach will be followed throughout the project lifetime which will train the candidate in sound working practices applicable to other advanced work environments. The experimental work will be carried out at National Physical Laboratory in Teddington with access to their precise timing infrastructure, engineering services, IT support etc.

For more information, please contact Prof. Chris Foot or Dr Krzysztof Szymaniec

Professor Gianluca Gregori

High Energy Density Laboratory Astrophysics - Scaling the Cosmos to the Laboratory

We are looking for DPhil experimental/theoretical positions to study and simulate in the laboratory extreme astrophysical conditions. The research is focussed on the following themes:

1. Investigation of the equation of state of ultra dense matter as the one occurring in the core of giant planets (such as Jupiter and many exoplanets). The experimental work involves using high power laser facilities to compress the matter to densities above solid and then applying x-ray techniques to probe its microscopic state. Interested students can also focus their work onto theoretical topics involving strongly coupled and partially degenerate plasmas - which are particularly relevant for describing white dwarf structure.

2. The understanding of the generation and amplification of magnetic fields in the Universe. We are particularly interested at the role of turbulence (and dynamo) in producing the present day values of magnetic fields in cluster of galaxies. Experiments on large laser facilities are planned in order to simulate in the laboratory intra-cluster turbulence and measure the resultant magnetic field generation and amplification by dynamo.

3. Quantum gravity with high power lasers. The idea is to use high intensity lasers to drive electrons to very high accelerations and then observe effects connected to the Unhruh-Hawking radiation. The ideal candidate is expected to work in defining the required experimental parameters and the proposal for a future experiment.

Our group has access to several laser facilities (including the National Ignition Facility, the largest laser system in the world). Students will also have access to a laser laboratory on campus (currently hosting the largest laser system in the department), where initial experiments can be fielded. Further details can be found by browsing our research web-page

For more information, please contact Prof. Gianluca Gregori

Professor Simon Hooker

Plasma accelerators

In a laser wakefield accelerator an intense laser pulse propagating through a plasma excites a trailing plasma wave via the action of the ponderomotive force, which acts to expel electrons from the region of the laser pulse. The longitudinal electric field in this plasma wakefield can be as high as 100 GV / m, more than three orders of magnitude larger than that found in conventional RF accelerators such as those used at CERN. Particles injected into the correct phase of the plasma wave can therefore be accelerated to energies of order 1 GeV in only a few tens of millimetres.

Theoretical and experimental work on plasma accelerators in Oxford is undertaken by a collaboration of research groups in the sub-departments of Particle Physics and Atomic & Laser Physics.

Please note that applications to work in this area should be made to the sub-department of Particle Physics, as explained at ; this page also gives further information on DPhil projects which are available in this area.

For more information, please contact Prof. Simon Hooker

Professor Dieter Jaksch

Solving non-linear PDEs on a quantum computer

This project is concerned with solving non-linear partial differential equations (PDEs) on a quantum computer. Recently, it has been shown that an exponential speedup in conventional multigrid (MG) methods for solving non-linear PDEs on a classical computer can be obtained via MG renormalization (MGR) methods [Journal of Computational Physics 372, 587 (2018)]. In this project, the DPhil student will implement MGR methods on a quantum computer focussing on industrially relevant problems in fluid dynamics. Based on current timetables for the future availability of quantum hardware (e.g. through our partnership with IBM), we expect our quantum algorithms to outperform classical computers within the next 3 – 5 years. Since non-linear PDEs are ubiquitous in all areas of science and technology, our method has the potential to leverage the use of quantum-enhanced algorithms in a broad range of real-world applications. The main tasks are:

(i) developing optimized implementations of algorithms for solving non-linear PDEs on existing quantum devices aiming to achieve an exponential speedup. This entails developing platform-specific algorithms mitigating their individual weaknesses such that a quantum advantage can be obtained. The student will consider quantum devices based on trapped ions and in particular the Q20:20 machine, as well as devices on IBM’s quantum computing network.

(ii) identifying industrially relevant applications where MGR methods on a quantum computer could help solving outstanding problems or improve the quality of existing solutions. This part of the project will be carried out in close collaboration with BAE Systems, who are interested in solving complex fluid dynamics problems that are modelled by non-linear PDEs.

For more information, please contact Prof. Dieter Jaksch

Dr Axel Kuhn

Demonstration of a cavity-based photonic entangler

Entanglement, in which two quantum systems can exhibit correlations that are greater than the limit allowed by classical physics, is one of the most intriguing predictions of quantum mechanics. Entanglement between remote atoms or ions is a key resource for quantum computing, and plays a central role in NQIT, the Oxford-led quantum technology hub.

We propose two schemes for entangling remote atoms: one probabilistic and one deterministic. In the probabilistic scheme, two distant atoms each emit a photon which are combined at the two input ports of a 50:50 beamsplitter. If the photons are detected at different output ports, then the atoms are projected into an entangled state. In place of a simple beam splitter, we also anticipate using more complex photonic networks [A. Holleczek, PRL 117, 023602 (2016)] in combination with active optical photon switching and routing. In the deterministic scheme, an atom emits a single photon which is reabsorbed by a second atom by running the emission process in reverse [J. Dilley, PRA 85, 023834 (2012)]. In doing so, the state of the first atom is entangled with that of the second. In both schemes, a high-finesse optical cavity is used to enhance the light-atom interactions.

Currently, we have two optical cavity experiments with random atom loading. The first phase of the project will be to build an optical dipole trap to permanently hold single atoms in the cavities. The feasibility of this approach has recently been demonstrated [D. Stuart, arXiv:1708.06672], and suitable fibre-tip and FIB-milled cavity mirrors are at present under development. The second phase will be to generate and quantify the entanglement between the two remote atoms using full Bell-state tomography.

Person specification

This is a highly challenging experimental project which will push the limits of laser and optical technology. It would suit a student with experience in atomic and laser physics and a keen interest in exploring quantum phenomena experimentally.

Work environment

The research team does encompass two postdocs and four graduate students which operate three laboratories dedicated to cavity-qed and atom-photon coupling in cavities at the Physics department of the University of Oxford. The work space is well equipped, comprising four vacuum chambers for studying atom-photon coupling in cavities, a large number of ECDL and fibre lasers for atom manipulation, a frequency comb for synchronously stabilising all laser and cavity frequencies, and a large battery of single-photon counters. The project builds on the current work by other graduate students in our group, atom-cavity coupling and strong cavity coupling.

The new student will directly contribute towards achieving cavity-mediated remote entanglement. All necessary apparatus exists within NQIT, including high-finesse cavities, vacuum chambers, and all lasers for trapping and driving the photon production process. Close support on a day-to-day basis will be provided by at least one Oxford PDRA for the duration of the project.

For more information, please contact Prof. Axel Kuhn

Professor Alexander Lvovsky

1. Superresolution imaging via linear optics in the far-field regime

Rayleigh's criterion defines the minimum resolvable distance between two incoherent point sources as the diffraction-limited spot size. Enhancing the resolution beyond this limit has been a crucial outstanding problem for many years. A number of solutions have been realized; however, all of them so far relied either on near-field or nonlinear-optical probing, which makes them invasive, expensive and not universally applicable. It would therefore be desirable to find an imaging technique that is both linear-optical and operational in the far-field regime. A recent theoretical breakthrough demonstrated that “Rayleigh’s curse” can be resolved by coherent detection the image in certain transverse electromagnetic modes, rather than implementing the traditional imaging procedure, which consists in measuring the incoherent intensity distribution over the image plane. To date, there exist proof-of-principle experimental results demonstrating the plausibility of this approach. The objective of the project is to test this approach in a variety of settings that are relevant for practical application, evaluate its advantages and limitations. If successful, it will result in a revolutionary imaging technology with a potential to change the faces of all fields of science and technology that involve optical imaging, including astronomy, biology, medicine and nanotechnology, as well as optomechanical industry.

For more information, please contact Prof. Alexander Lvovsky

2. Optical neural networks

Machine learning has made enormous progress during recent years, entering almost all spheres of technology, economy and our everyday life. Machines perform comparably to, or even surpass humans in playing board and computer games, driving cars, recognizing images, reading and comprehension. It is probably fair to say that a modern machine will perform better than a human in any environment it has complete knowledge of. These developments however impose growing demand on our computing capabilities, including both the size of neural networks and the processing rate. This is particularly concerning in view of the decline of Moore’s law.

The project is to implement artificial neural networks using optics rather than electronics. The training of neural network consists of linear operations (matrix multiplication) combined with nonlinear activation functions applied to individual units. Both these operations can be implemented optically using lenses, spatial light modulators and nonlinear optical techniques such as saturable absorption. However, one crucial element of the training procedure - so-called backpropagation - has so far remained elusive. Our group has developed an idea to overcome this obstacle and implement pure optical backpropagation in a neural network, thereby enabling the training that is practically electronics-free. We confirmed the viability of this approach by simulation. Our next goal – and the goal of this doctoral research project – is to set up an experiment and test the method in a practical setting.

For more information, please contact Prof. Alexander Lvovsky

3. Quantum machine learning

Quantum machine learning is an emerging interdisciplinary field that deals both with the application of quantum technology to accelerate the performance of neural networks, or, conversely, applying machine learning methods to solve problem in quantum physics. In this project, we are concerned with the latter. More specifically, we are interested in quantum variational optimization – the problem of finding the quantum state that best satisfies a certain criterion. Examples include determining the ground state of a certain Hamiltonian, quantum tomography (state estimation from measurements) and quantum chemistry. The Hilbert space dimension, and hence the number of parameters describing the state of a quantum system, grows exponentially with its size and becomes unwieldy very quickly; hence the ability of machine learning algorithms to analyze and find regularities in large datasets is extremely useful. The results of this research have a broad spectrum of applications, including drug and new material discovery, understanding biological processes, quantum computation and communications.

For more information, please contact Prof. Alexander Lvovsky

Professor David Lucas

Entangling gates with performance close to fundamental limits

The Oxford and NIST Boulder ion trap groups have both demonstrated two-qubit entangling gates with world-record 99.9% fidelity, significantly higher than in any other qubit platform [Ballance et al. Phys.Rev.Lett. 2016, Gaebler et al., Phys.Rev.Lett. 2016]. However, the error is still about one order of magnitude above the quasi-fundamental limit set by Raman photon scattering. Oxford have also recently achieved the fastest (480ns) entangling gate in ion traps [Schäfer et al., Nature 2018] which is similar in speed to the recently-demonstrated two-qubit gates in silicon devices. This project will have the ambitious goal of minimizing the remaining technical errors, to push the best fidelity closer to the photon scattering limit of 99.99%. The student will also investigate the practicality of demonstrating new ideas for accelerating the gate speed further by control of the optical phase of the laser field that drives the gate, and/or reduction of the Lamb-Dicke parameter.

We are looking for a highly motivated first-class student to join these world-leading projects. For further information, please see our web page at

For more information, please contact Prof. David Lucas

Professor David Lucas & Professor Andrew Steane

Ion trap optical cavities for next-generation quantum networking

The NQIT vision of quantum computing (see using distributed modular processors (network “nodes”) is limited by low entanglement rates between different nodes. The current state-of-the-art is <10Hz; we are aiming for ~1kHz average rate, but this is close to the limit imposed by the collection efficiency of the largest NA lens (NA 0.6) that is practical for photon collection. The long-term intention has always been to use optical cavities, which can in principle increase the photon collection probability close to unity, which would offer MHz entanglement rates between nodes. The technical challenges of integrating optical cavities and ion traps are formidable, hence cavities do not form part of the “Q20:20 machine” first-generation design. However, we would like to explore methods of combining cavities with microfabricated ion traps, and colleagues at Southampton have already undertaken some exploratory fabrication tests in this direction. The goal of this project will be to design and fabricate a simple ion trap / cavity system, in collaboration with microfabrication experts Southampton, and test it at Oxford. The use of cavities will be a critical research strand of our planned “phase 2” UK Quantum Technology “Hub” project, a ~£30M cross-disciplinary effort which, if awarded, will begin in Dec 2019.

We are looking for a highly motivated first-class student to join these world-leading projects. For further information, please see our web page at

For more information, please contact Prof. David Lucas

Professor Peter Norreys

1. Maximising plasma turbulence in the hot spot of inertial fusion targets

The student will investigate, using relativistic fluid theory and Vlasov-Maxwell simulations, the local heating of a dense plasma by two crossing electron beams generated during multi-PW laser-plasma interactions with a pre-compressed, inertial fusion target. Heating occurs as an instability of the electron beams that drives Langmuir waves, which couple non-linearly into damped ion-acoustic waves and into the background electrons. Initial simulations show a factor-of-2.8 increase in electron kinetic energy with a coupling efficiency of 18%. By considering the collisionless energy deposition of these electron beams, we are able to demonstrate, via sophisticated radiation-hydrodynamic simulations, that this results in significantly increased energy yield from low convergence ratio implosions of deuterium-tritium filled “wetted foam" capsules, as recently demonstrated on the National Ignition Facility. This approach promises to augment the heating of the central hot spot in these targets, and is attractive as a complementary approach that of fast ignition inertial fusion.

The student will:
• Simulate (Vlasov or possibly particle-in-cell) parameter scan of the energy cascade. The question is how dependent are we upon the electron energy, thermal spread, divergence, beam-to-background density ratio.
• Simulate the energy cascade process in an inhomogeneous plasma.
• Simulate energy cascade using finite beams.
• Help design experiments verifying the energy cascade process.
The student will also use machine learning to study the optimisation of the energy deposition process.

For more information, please contact Prof. Peter Norreys

2. Laser-Plasma Interaction Physics for Inertial Fusion and Extreme Field Science

Intense lasers have extraordinary properties. They can deliver enormous energy densities to target, creating states of matter in the laboratory that are otherwise only found in exotic astrophysical phenomena, such as the interiors of stars and planets, the atmospheres of white dwarfs and neutron stars, and in supernovae. The behaviour of matter under these extreme conditions of density and temperature is a fascinating area of study, not only for understanding of fundamental processes that are, in most cases, highly non-linear and often turbulent, but also for their potential applications for other areas of the natural sciences.

My team is working on:
• Inertial confinement fusion - applications include energy generation and the transition to a carbon-free economy and the development of the brightest possible thermal source for neutron scattering science
• New high power optical and X-ray lasers using non-linear optical properties in plasma
• Novel particle accelerators via laser and beam-driven wakefields - including the AWAKE project at CERN, as a potential route for a TeV e-e+ collider
• Unique ultra-bright X-ray sources

The understanding of these physical processes requires a combination of observation, experiment and high performance computing models on the latest supercomputers. My team is versatile, combining experiment, theory and computational modelling, including applications of machine learning - I can offer projects in all of these areas.

For more information, please contact Prof. Peter Norreys

Dr Robert Smith

Single Impurity in a dipolar Bose-Einstein Condensate

A single impurity interacting with a quantum bath is a simple (to state) yet rich many-body paradigm that is relevant across a wide sweep of fields from condensed matter physics to quantum information theory to particle physics. The aim of this project is to create a highly controllable setting in which to study this physics. This starting point for this project will be our existing Erbium cold-atom machine. The special feature of Erbium atoms is their large magnetic dipole moments which result in long-range and anisotropic dipole-dipole interactions in addition to the short-range contact interactions more normally seen in cold atom systems. This project will involve adding a second atomic species to the experiment and using the resulting system to study a range of topics from polaron physics to information flow in open quantum systems.

For more information, please contact Dr Robert Smith

Dr Sam Vinko

Exploring quantum high energy density matter via Resonant Inelastic X-ray Scattering (RIXS)

The advent of high-brightness 4th generation free-electron laser (FEL) light sources has revolutionised our ability to study dense plasmas with unprecedented precision and control. The addition of new high-repetition rate, high energy laser drivers to FEL beamlines, such as the Dipole laser at the high-energy-density (HED) endstation of the European XFEL, will allow for a host of new compression experiments in well-controlled HED conditions to be investigated. In particular, the capability to tune the inter-atomic spacing between atoms in plasmas and compressed solids to the point where inner-shell electrons start overlapping, interacting and hybridizing, is of particular interest as it will provide unparalleled experimental access to a new quantum frontier in dense plasmas.

This project aims to develop the spectroscopic tools needed to diagnose such systems, and apply them to experimental campaigns at FEL facilities world-wide. We will focus primarily on methods to extract the detailed electronic structure and excitation spectrum of HED systems via resonant inelastic x-ray scattering (RIXS). By using RIXS to explore the time-resolved density of states in highly compressed systems we will explore whether core-electron-hybridization does take place at high densities, and if it can lead to new forms of bonding in extreme conditions. We will further investigate the nature of electron de- and re-localization, and study how the depression of the ionization energy in plasmas changes as a function of density.

On the computational side the project will leverage the substantial capabilities present in the group on atomic kinetics and quantum electronic structure simulations, and on machine learning approaches to large-scale data analysis, including the use of fast deep-learning-based emulators and intelligent optimization. This will ensure we will be able to make best use of the highly valuable and limited experimental time on FELs to extract maximum information from high-repetition rate, high-throughput experimental campaigns.

This project will be conducted in collaboration with the research groups of Prof. Justin Wark and Prof. Gianluca Gregori.

For more information, please contact Dr Sam Vinko

Professor Justin Wark

Title TBA

Despite the impressions that might be gained within an undergraduate physics course, there are still vast ranges of the phase diagram of matter (in temperature and density space) that remain, both from an experimental and theoretical point of view, largely unexplored. One particular class of matter is so-called warm-dense matter, by which we mean materials at about solid density, but taken to temperatures through and beyond the melt, such that they start to become partially ionised plasmas. These systems are of fundamental scientific interest, as they actually represent a significant fraction of the observable matter in the universe - being the the conditions that prevail within a giant exoplanet, or deep within a star. The problem in understanding this state is that the thermal energies and binding energies are of the same magnitude, and as such one type of energy cannot be taken to be a perturbation on the other (e.g. in a gas the binding energy is usually taken as perturbation to the thermal energy, and vice versa in a solid). There is therefore much interest in being able to create and study such matter in the laboratory, and in the development of sophisticated first principles quantum-based models to understand it. From the experimental perspective, one recent advance that can significantly impact this field is the development of free-electron x-ray lasers. These are ~ 100-fsec sources of x-rays, produced by electrons accelerated to relativistic energies and passed through extremely long periodic magnetic structures. These novel sources of x-rays are more than a billion times brighter than any other type of x-ray source on the planet. By focussing these sources onto thin solid foils, we can heat the foils to extreme temperatures, far into the plasma regime, before they have had time to move even a single lattice spacing - they thus remain at solid density, but become very hot. We therefore can create and interrogate (via diffraction, inelastic scattering, spectroscopy, etc.) matter under exactly the sort of conditions in which we are interested.

The project offered here is a fully-funded (stipend, fees, and necessary funds for travel to experiments and conferences) DPhil project, sponsored by OxCHEDS (the Oxford Centre for High Energy Density Science) and AWE Aldermaston, to use x-ray lasers (primarily the new FEL based in Hamburg, Germany, although we may also use the system in Stanford, California) to create, study, and develop the theory of, such matter. The experimental part of this project will involve irradiating solid materials with x-rays at unprecedented intensities on ultra-short timescales, and recording both emitted and scattered photons. The theoretical part of the project will involve undertaking multi-million atom molecular dynamics calculations to predict target response, and may also involved some ab initio calculations based on quantum density functional theory.

The lead supervisor on the project will be Professor Justin Wark, and will be co-supervised by Prof. Gianluca Gregori, and Dr Sam Vinko. Candidates interested in the project must be willing to undertake some foreign travel, although the majority of the work will be spend in Oxford undertaking simulation and analysis. X-Ray free electron lasers rank amongst the most revolutionary scientific technologies of the past decade, to the extent that new ideas for experiments and routes of inquiry abound. As such, as well as the normal plethora of skills that a graduate student would gain by undertaking a thesis program, this project, and the skills gained by undertaking it, afford the opportunity to join and contributed to a new branch of science that is very much in its infancy.

For more information, please contact Prof. Justin Wark