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Quantum Many-Body Scars and Weak Ergodicity Breaking in Rydberg-Atom Quantum Simulators


Key facts

Type of research degree
Application deadline
Ongoing deadline
Project start date
Friday 1 October 2021
Country eligibility
International (open to all nationalities, including the UK)
Competition funded
Source of funding
University of Leeds
Dr Zlatko Papic
School of Physics and Astronomy
Research groups/institutes
Theoretical Physics
<h2 class="heading hide-accessible">Summary</h2>

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 &amp;quot;forget&amp;quot; its initial state. This can be visualised as an ice cream that melts away and never finds its way back to the frozen state. &amp;quot;Quantum scars&amp;quot; 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. Our recent work [Nature Physics 14, 745 (2018)] has proposed the first theoretical explanation for this phenomenon and named it &amp;quot;quantum many- body scars&amp;quot;. At this point, the origins of quantum many-body scars largely remain a mystery. Your project will develop a computer simulation of quantum many-body scars in two-dimensional lattices of Rydberg atoms, with the goal of predicting future experiments on these systems that may unlock a range of applications in the emerging quantum technologies.

<h2 class="heading hide-accessible">Full description</h2>

<p>Recent state-of-the-art experiments on a quantum simulator built from strongly-correlated Rydberg atoms [H. Bernien et al., Nature 551, 579 (2017)] have discovered a remarkable dynamical phenomenon that challenged the conventional notion of how quantum systems reach thermal equilibrium. We have recently proposed the first theoretical explanation for this phenomenon and named it &quot;quantum many-body scars&quot; [Nature Physics 14, 745 (2018]. Following the surge of international interest in this topic, including <a href="">popular articles in the press</a>, this project will contribute to the on-going quest to understand the mathematical origins of quantum many-body scars and their unusual dynamical properties. The practical benefits of this research will be new computational techniques for simulating non-ergodic many-body dynamics and phases of matter, and their potential use as a platform for robust quantum technology that could operate at arbitrarily high temperatures.&nbsp;&nbsp;</p> <p>The initial phase of the project will focus on: (i) learning about quantum dynamics, thermalisation, and related phenomena (integrability, many-body localisation), and (ii) learning how to numerically simulate quantum many-body systems (e.g., using Python, C++, or any preferred language). In particular, you will learn how to apply quantum information concepts to characterise dynamics and thermalisation (e.g., entanglement entropy and spectrum). You will apply all these tools to investigate in the detail the toy model of a 1D Rydberg atom chain, then extend the known results by investigating various physical perturbations to the model.</p> <p>Desired student background:&nbsp;We seek talented and highly-motivated physics students to pursue this project in the general area of quantum many-body physics, which intersects with the fields of quantum information and condensed matter physics. A significant component of the project is numerical modelling of quantum many-body systems via exact diagonalisation and related techniques (e.g., matrix product states, DMRG, etc.), thus the project is particularly suitable for those with strong interest in computational physics and numerical simulations.</p>

<h2 class="heading">How to apply</h2>

<p>Formal applications for research degree study should be made online through the&nbsp;<a href="">University&#39;s website</a>. Please state clearly in the research information section&nbsp;that the research degree you wish to be considered for is &ldquo;Quantum Many-Body Scars and Weak Ergodicity Breaking in Rydberg-Atom Quantum Simulators&rdquo; as well as&nbsp;<a href="mailto:">Dr Zlatko Papic</a> as your proposed supervisor.</p> <p>If English is not your first language, you must provide evidence that you meet the University&#39;s minimum English language requirements (below).</p> <p><em>We welcome applications from all suitably-qualified candidates, but UK black and minority ethnic (BME) researchers are currently under-represented in our Postgraduate Research community, and we would therefore particularly encourage applications from UK BME candidates. All scholarships will be awarded on the basis of merit.</em></p>

<h2 class="heading heading--sm">Entry requirements</h2>

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.

<h2 class="heading heading--sm">English language requirements</h2>

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.

<h2 class="heading">Funding on offer</h2>

<p><strong>Self funding students are welcome to apply.</strong></p> <p><strong>UK</strong>&nbsp;&ndash;&nbsp;The&nbsp;<a href="">Leeds Doctoral Scholarship (January deadline)</a>&nbsp;and the&nbsp;<a href="">Henry Ellison Scholarship</a>&nbsp;are available to UK applicants. The&nbsp;<a href="">Bell Burnell Scholarship Award</a>&nbsp;is available to support applicants who are from groups that are currently under-represented in physics (awarded by the IOP).&nbsp; <a href="">Alumni Bursary</a> is available to graduates of the University of Leeds.</p> <p><strong>Non-UK</strong>&nbsp;&ndash; The&nbsp;<a href="">School of Physics &amp; Astronomy Fee Only Scholarship</a>&nbsp;is available to support the additional academic fees of international applicants. The&nbsp;<a href="">China Scholarship Council - University of Leeds Scholarship</a>&nbsp;is available to nationals of China. The&nbsp;<a href="">Leeds Marshall Scholarship</a>&nbsp;is available to support US citizens. The&nbsp;<a href="">Bell Burnell Scholarship Award</a>&nbsp;is also available to international applicants and supports those who are from groups that are currently under-represented in physics (awarded by the IOP). <a href="">Alumni Bursary</a> is available to graduates of the University of Leeds.</p> <p>&nbsp;</p>

<h2 class="heading">Contact details</h2>

<p>For further information regarding the application procedure, please contact Doctoral College Admissions,<br /> e: <a href=""></a>, t: +44 (0)113 343 5057.</p>

<h3 class="heading heading--sm">Linked research areas</h3>