Séminaire du LPTMS : Marko Medenjak (LPENS)

Bounds on time translation symmetry breaking

Marko Medenjak (LPENS)

Online seminar — Zoom Meeting ID: 951 9908 9593 — Passcode: ask L. Mazza and D. Petrov —

Abstract: Isolated systems consisting of many interacting particles are generally
assumed to relax to a stationary state, whose macroscopic properties are
described by the laws of thermodynamics and statistical physics. In this
seminar we will explore whether quantum systems can avoid relaxation and
if stationarity itself can be unstable, meaning that even the slightest
disturbance of the thermal state leads to perpetually changing physical
properties. Analogous behaviour was experimentally observed in driven
quantum systems (Floquet time crystals), in which the response of the
system does not follow the period of the driving. We will show that time
translation symmetry breaking is possible even in perfectly isolated
quantum systems without any driving, and provide rigorous bounds on it
in terms of dynamical symmetries. Finally, we will see how time
translation symmetry breaking occurs in the Heisenberg XXZ spin chain,
and show that its properties are a no-where continuous (fractal)
function of the system parameters.

[1] M. Medenjak, B. Buča, and D. Jaksch, Phys. Rev. B 102, 041117(R) (2020).
[2] M. Medenjak, T. Prosen, and L. Zadnik, SciPost Phys. 9, 3 (2020).

Date/Time : 25/05/2021 - 11:00 - 12:00

Location : LPTMS (100% online seminar)