Collège Doctoral - Doktorandenkollegien

Statistical Physics of Complex Systems

Coventry - Leipzig - Lviv - Nancy

PhD positions


Title Quantum quench from a thermal tensor state: Boundary effects and generalized Gibbs ensemble
Authors Collura M., Karevski D.
Reference Phys. Rev. B 89 (2014) 214308
Abstract We consider a quantum quench in a noninteracting fermionic one-dimensional field theory. The system of size L is initially prepared into two halves L ([−L/2,0]) and R ([0,L/2]), each of them thermalized at two different temperatures TL and TR, respectively. 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 (L→∞), we 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. We show, in such a case, that the two-point correlation functions are deduced, at large times, from a simple nonequilibrium 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.

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