Beecroft Building, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU
Dr Berislav Buca, CNRS, Universite Paris-Saclay
Abstract
This talk is based on a previous proof that quantum many-body systems, rather than merely reaching a Gibbs ensemble in the long-time limit, are, following a quench, always in a time-dependent Gibbs ensemble with chemical potentials that can decay in time. The corresponding conservation laws are called "transient dynamical symmetries"
In this talk, I will show how to use Krylov subspace methods to identify these "transient dynamical symmetries". Moreover, I will provide analytical results for these based on the universal operator growth hypothesis and a careful truncation of the Krylov space - chaotic systems have only a finite number of different complex frequencies giving the corresponding decay rates of the chemical potential of the transient dynamical symmetries. The transient dynamical symmetries can likewise be identified in the generic chaotic, integrable, and free cases.
This approach of eternal equilibrium can give universal analytical results for dynamics of local observables far from equilibrium and efficient numerical calculations in concrete example systems.
References:
N. Loizeau, B. Buca, D. Sels. In preparation.
B. Buca. Phys. Rev. X 13, 031013 (2023).
D. E. Parker, X. Cao, A. Avdoshkin, T. Scaffidi, E. Altman. Phys. Rev. X 9, 041017 (2019).