Theory Group Seminars

Quantum quench from a thermal tensor state: boundary effects and generalized Gibbs ensemble

by Mario Collura (Pisa University)

Tuesday, 18 February 2014 from to (Europe/Rome)
at Building C, First Floor ( 248 )
Description
In this talk I will consider a quantum quench in a non-interacting fermionic one-dimensional field-theory. The system of size L is initially prepared into two halves, each of them thermalized at two different temperatures. At a given time the two halves are joined together by a local coupling and the whole system is left to evolve unitarily. For an infinitely extended system, I will show that the time evolution of the particle and energy densities is well described via a hydrodynamic approach which allows us to evaluate the correspondent stationary currents. In such a case, the two-point correlation functions are deduced, at large times, from a simple non-equilibrium steady state. Otherwise, whenever the boundary conditions are retained (in a properly defined thermodynamic limit), any current is suppressed at large times, and the stationary state is described by a generalized Gibbs ensemble, which is diagonal and depends only on the post-quench mode occupation.