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

Mario Collura; Dragi Karevski

doi:10.1103/PhysRevB.89.214308

paper

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

arXiv:1402.1944 · doi:10.1103/PhysRevB.89.214308

Abstract

We consider a quantum quench in a non-interacting 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, $T_{L}$ and $T_{R}$ 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 ( $L \to \infty$ ), 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 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.

12 pages, 9 figures, Fig.6 improved, Sec. IVC largely modified, Sec. V improved, references added

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

Abstract

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