Tues. Joint seminar - 11:00 a.m.

[Cond.Matt. & Stat.Mech.Section]

JOINT ICTP/SISSA STATISTICAL PHYSICS SEMINAR



Tuesday, 3 March  -   11:00 hrs.

 

Luigi Stasi Seminar Room -  ICTP Leonardo Building - 1st floor

 

Gabriele MARTELLONI    ( SISSA )



"Quantum Quench from a thermal tensor state: Two stationary states, NESS and CGE"

 
Abstract

We consider a non-interacting Fermi gas in d dimensions, both in the non- relativistic and relativistic case. The system of size L_d is initially prepared into two halves L and R, each of them thermalized at two different temperatures, T_L and T_R respectively. At time t = 0 the two halves are put in contact and the entire system is left to evolve unitarily. We show that, in the thermodynamic limit, the time evolution of the particle and energy densities is perfectly described by a semiclassical approach which permits to analytically evaluate the correspondent stationary currents. In particular, in the case of non-relativistic fermions, we find a low-temperature behavior for the particle and energy currents which is independent from the dimensionality d of the system, being proportional to the difference T_L2− T_R2. Moreover we consider the same problem of two halves, thermalized at different temperatures, for two 1d XX chains using the Quench Action Method (QAM). We show that two different stationary regimes are reached at long times, depending on the interplay between the observation time scale T and the total length L of the system. We show the emergence of a non-equilibrium steady state (NESS) supporting an energy current for observation time T much smaller than the system size L. We then identify a longer time-scale for which thermalization occurs in a Generalized Gibbs Ensemble (GGE).