Leeds-Loughborough-Nottingham Non-Equilibrium Seminars

Following the tradition from the previous years,  the Universities of Leeds (Dr. Papic), Loughborough (Dr. Lazarides) and Nottingham (Prof. Garrahan) will be running a joint hybrid seminar series on non-equilibrium physics during 2022/23. “Hybrid” means that some of the seminars will be delivered in person in one of the Universities and broadcast remotely in others, while some seminars will be fully online.

The seminars will be on Zoom and typically take place on Wednesdays at 3pm UK time:

Leeds-Loughborough-Nottingham Zoom Seminar

https://universityofleeds.zoom.us/j/81863636407?pwd=aitNN0pXWmJGSjhUMFFCVnFrSys1Zz09

Meeting ID: 818 6363 6407

Passcode: 1828#Ab

For a complete list of previous seminars in 2020/21 and 2021/22, please see the archive on the left.

Seminar schedule (evolving)

  • 29 November, 3pm: Gil Refael, Caltech ***NOTE: DAY CHANGE DUE TO INDUSTRIAL ACTION***

  • 7 December, 3pm: Lorenzo Piroli, ENS

Previous seminars

  • 23 November, 3pm: Curt von Keyserlingk, Kings College London

  • 16 November, 3pm: Žiga Krajnik, Ljubljana

  • 2 November, 3pm: Maarten van Damme, Ghent

Title: Tangent vectors and spectral functions
Abstract: Spectral functions are perhaps the most elementary dynamical quantity. They are not only interesting by themselves, as a clear signature of the low-lying excitations, but they are also experimentally measurable. This makes them an important target for numerical simulations. In this talk I will go over some recent algorithmic developments in the field of tensor networks that are relevant for non-equilibrium physics, primarily focused on the calculation of spectral functions.
  • 26 October, 3pm: Max McGinley, Oxford

Title: Measuring many properties of a quantum state in analog quantum simulators

Abstract: One of the many potential uses of a quantum computer is to simulate complex many-body quantum phenomena that would be computationally intractable on a classical computer. At present, fully programmable quantum computers are limited in terms of their size and noisiness. However, some experimental platforms are particularly well-suited to quantum simulation, even if they do not possess full programmability. In such analog quantum simulators, which include ultracold atomic gases and arrays of Rydberg atoms in optical tweezers, one typically has global control over interactions, instead of individual site-selective control. While this allows many interesting kinds of dynamics to be synthesised, accessing expectation values of certain observables remains challenging, due to the intrinsic limitations in programmability. In this talk, I will introduce a scheme that allows one to measure any property of a quantum state, including nonlinear functionals such as Renyi entropies, using only global control over the dynamics, making it particularly well-suited to analog quantum simulators. Crucially, the total number of experimental repetitions required to estimate a collection of observables can be bounded in the same way as in classical shadow tomography [1], which is a provably optimal protocol designed for fully programmable devices. The success of our scheme is rooted in the recently discovered phenomenon of “deep thermalization” [2], where quantum state designs emerge naturally from deterministic chaotic dynamics. I will present simulations of our protocol, which allow us to benchmark its performance, and discuss how the effects of noise can be mitigated. [1] Huang et al., Nat. Phys. 16, 1050 (2020) [2] Cotloer et al., arXiv:2103.03536 This talk is based on: MM, M. Fava, S. Biswas (arXiv — to appear)

  • 05/10/2022, 3pm: Jonathon Riddell (McMaster University)Title: Concentration of equilibration and an estimate of the recurrence timeAbstract: In this talk we will first explore the problem of equilibration and the emergence of static equilibrium in isolated quantum many body systems. We will then show that the dynamics of generic quantum systems concentrate around their equilibrium value when measuring at arbitrary times. In particular, we show that the probability of finding the system away from equilibrium is doubly exponentially supressed in system size. We will then use these concentration results to put a lower bound on the recurrence time.