Quantum Simulation of Out-of-Equilibrium Dynamics of Gauge Theories

A perennial mystery of nature is how order can exist amidst chaos. Familiar systems such as the clock pendulum exhibit regular periodic motion. This ordered behaviour, however, is fragile. For example, interactions between particles rapidly lead to chaos, forcing the system to thermalise and forget its initial state. This can be visualised as an ice cream that melts away and never finds its way back to the frozen state. Quantum scars refer to the surprising behaviour that defies such common intuition: for special initial states, the ice cream periodically melts away and then freezes up again. Recent experiments on ultracold Rydberg atoms have found evidence of similar behaviour where the atoms were able to return to their initial state many times during the measurement. This project seeks to develop an understanding of quantum scars in systems of ultra cold atoms in optical lattices, with the goal of predicting future experiments that may unlock a range of applications in the emerging quantum technologies.

<p class="MsoNoSpacing">We are witnessing a revolution in our ability to engineer and explore complex quantum matter. Programmable platforms ultracold atoms, Rydberg arrays, trapped ions, superconducting qubits now allow physicists to build quantum systems from the bottom up, drive them far from equilibrium, and monitor their dynamics with single-particle resolution. These quantum simulators are more than powerful calculators: they are laboratories for fundamental physics, where you can watch metastable states decay, gauge fields fluctuate, and unexpected forms of order emerge from chaos. Our group have already helped shape this frontier. Our discovery of quantum many-body scars, a mechanism of weak ergodicity breaking in otherwise thermalising systems, revealed that some systems like Rydberg atom arrays can sustain long-lived coherent dynamics [Nat. Phys. 17, 675 (2021); arXiv:2011.09486]. More recently, we realised the enigmatic phenomenon of false-vacuum decay on a quantum annealer [Nat. Phys. 21, 396 (2025); arXiv:2406.14718], observing quantised bubble nucleation and interacting bubbles that mimic the decay of a metastable universe.</p> <p>In this PhD project you will harness quantum simulators to explore lattice gauge theories (LGTs)—discrete counterparts of the gauge field theories underpinning the Standard Model. Even simplified models capture hallmark phenomena such as confinement, string breaking and topological sectors, while remaining accessible to current hardware. You will design and analyse protocols that realise these models on Rydberg arrays or trapped-ion chains, and develop advanced numerical tools (tensor networks, exact diagonalisation) to predict their real-time behaviour. Building on our false-vacuum work, you will investigate metastability and bubble nucleation dynamics, asking how Gauss-law constraints and confining strings reshape the decay of false vacua. In parallel, you will search for new forms of ergodicity breaking, extending the concept of quantum scars to settings with local gauge symmetries and exploring their impact on vacuum decay. Key questions include: can gauge constraints stabilise scarred subspaces or fragment the Hilbert space in higher dimensions? Do scar-induced revivals compete with, or enhance, bubble formation and string breaking? How do these phenomena evolve as you approach the continuum limit where particle-physics questions become relevant? By combining analytics, state-of-the-art simulations, and close interaction with experimental groups, you will chart a new territory where confinement, metastability and non-thermal dynamics meet. </p>

<p>Formal applications for research degree study should be made online through the <a href="https://www.leeds.ac.uk/research-applying/doc/applying-research-degrees">University's website</a>. Please state clearly in the Planned Course of Study that you are applying for <em><strong>PHD Physics & Astronomy FT</strong></em> and in the research information section that the research degree you wish to be considered for is <em><strong>Quantum Simulation of Out-of-Equilibrium Dynamics of Gauge Theories</strong></em> as well as <a href="mailto:https://eps.leeds.ac.uk/physics/staff/4124/dr-zlatko-papic">Prof Zlatko Papic</a> as your proposed supervisor and in the finance section, please state clearly <em><strong>the funding that you are applying for, if you are self-funding or externally sponsored</strong></em>.</p> <p>If English is not your first language, you must provide evidence that you meet the University's minimum English language requirements (below).</p> <p>Applications will be considered on an ongoing basis.  Potential applicants are strongly encouraged to contact the supervisors for an informal discussion before making a formal application.  We also advise that you apply at the earliest opportunity as the application and selection process may close early, should we receive a sufficient number of applications or that a suitable candidate is appointed.</p> <p><strong>If you are applying for University or School Scholarships for 2026/27 entry, with external sponsorship or you are funding your own study, please ensure you provide your supporting documents at the point you submit your application:</strong></p> <ul> <li>Full Transcripts of all degree study or if in final year of study, full transcripts to date including the grading scheme</li> <li>Personal Statement outlining your interest in the project</li> <li>CV</li> </ul> <p><em>As an international research-intensive university, we welcome students from all walks of life and from across the world. We foster an inclusive environment where all can flourish and prosper, and we are proud of our strong commitment to student education. Across all Faculties we are dedicated to diversifying our community and we welcome the unique contributions that individuals can bring, and particularly encourage applications from, but not limited to Black, Asian, people who belong to a minority ethnic community, people who identify as LGBT+ and people with disabilities. Applicants will always be selected based on merit and ability.</em></p>

Applicants to research degree programmes should normally have at least a first class or an upper second class British Bachelors Honours degree (or equivalent) in an appropriate discipline. The criteria for entry for some research degrees may be higher, for example, several faculties, also require a Masters degree. Applicants are advised to check with the relevant School prior to making an application. Applicants who are uncertain about the requirements for a particular research degree are advised to contact the School or Graduate School prior to making an application.

The minimum English language entry requirement for research postgraduate research study is an IELTS of 6.0 overall with at least 5.5 in each component (reading, writing, listening and speaking) or equivalent. The test must be dated within two years of the start date of the course in order to be valid.

<p><strong>Self-Funded or externally sponsored students are welcome to apply.</strong></p> <p><strong>Scholarship opportunities open from October 2025</strong></p> <p><strong>UK</strong> – The <a href="https://phd.leeds.ac.uk/funding/102-bell-burnell-scholarship-award-awarded-by-the-iop">Bell Burnell Scholarship Award</a> is available to support applicants who are from groups that are currently under-represented in physics (awarded by the IOP) <strong>(closing date: 12 December 2025)</strong>. The <a href="https://phd.leeds.ac.uk/funding/209-leeds-doctoral-scholarships-2024">Leeds Doctoral Scholarship</a> <strong>(closing date: 1 April 2026)</strong> and <a href="https://phd.leeds.ac.uk/funding/234-leeds-opportunity-research-scholarship-2022">Leeds Opportunity Research Scholarship</a> <strong>(closing date: 1 April 2026)</strong> are available to UK applicants.  <a href="https://phd.leeds.ac.uk/funding/60-alumni-bursary">Alumni Bursary</a> is available to graduates of the University of Leeds.</p> <p><strong>Non-UK</strong> – The <a href="https://phd.leeds.ac.uk/funding/48-china-scholarship-council-university-of-leeds-scholarships-2021">China Scholarship Council - University of Leeds Scholarship</a> is available to nationals of China <strong>(closing date: 7 January 2026)</strong>. The <a href="https://phd.leeds.ac.uk/funding/73-leeds-marshall-scholarship">Leeds Marshall Scholarship</a> is available to support US citizens. <a href="https://phd.leeds.ac.uk/funding/60-alumni-bursary">Alumni Bursary</a> is available to graduates of the University of Leeds.</p> <p>Please note that if you are successful in securing an academic offer for PhD study, this does not mean that you have been successful in securing an offer of funding.</p> <p>If you are applying for the Leeds Doctoral Scholarship, Leeds Opportunity Research Scholarship, China Scholarship Council-University of Leeds Scholarship or Leeds Marshall Scholarship, you will need to complete a separate application, specific to these scholarships, to be considered for funding.</p> <p>You will be responsible for paying the overtime fee in full in your writing up/overtime year (£340 in Session 2025/26), but the scholarship maintenance allowance will continue to be paid for up to 6 months in the final year of award.</p> <p><strong>Important</strong>: Please note that that the award does <em><strong>not </strong></em>cover the costs associated with moving to the UK.  All such costs (<a href="https://www.leeds.ac.uk/international-visas-immigration/doc/applying-student-visa">visa, Immigration Health Surcharge</a>, flights etc) would have to be met by yourself, or you will need to find an alternative funding source. </p> <p>Please refer to the <a href="https://www.ukcisa.org.uk/">UKCISA</a> website for information regarding Fee Status for Non-UK Nationals.</p>

<p>For further information about your application, please contact PGR Admissions by email to <a href="mailto:phd@engineering.leeds.ac.uk">phd@engineering.leeds.ac.uk</a></p> <p>For further information about this project, please contact Prof Zlatko Papic by email to <a href="mailto:Z.Papic@leeds.ac.uk">Z.Papic@leeds.ac.uk</a></p>