title: Correlations after quantum quenches in the XXZ spin chain: failure of the generalized Gibbs ensemble.
abstract: We study the nonequilibrium time evolution of the spin-1/2 anisotropic Heisenberg (XXZ) spin chain, with a choice of dimer product and Néel states as initial states. We investigate numerically various short-ranged spin correlators in the long-time limit and find that they deviate significantly from predictions based on the generalized Gibbs ensemble (GGE) hypotheses. By computing the asymptotic spin correlators within the recently proposed quench-action formalism [Phys. Rev. Lett. 110, 257203 (2013)], however, we find excellent agreement with the numerical data. We, therefore, conclude that the GGE cannot give a complete description even of local observables, while the quench-action formalism correctly captures the steady state in this case.
authors.affiliation: MTA-BME "Momentum" Statistical Field Theory Research Group, Department of Theoretical Physics, Budapest University of Technology and Economics, 1111 Budapest, Budafoki út 8, Hungary.
authors.forename: B
authors.initials: B
authors.lastname: Pozsgay
authors.affiliation: MTA-BME "Momentum" Statistical Field Theory Research Group, Department of Theoretical Physics, Budapest University of Technology and Economics, 1111 Budapest, Budafoki út 8, Hungary.
authors.forename: M
authors.initials: M
authors.lastname: Mestyán
authors.affiliation: MTA-BME "Momentum" Exotic Quantum Phases Research Group, Department of Theoretical Physics, Budapest University of Technology and Economics, 1111 Budapest, Budafoki út 8, Hungary.
authors.forename: M A
authors.initials: MA
authors.lastname: Werner
authors.affiliation: MTA-BME "Momentum" Statistical Field Theory Research Group, Department of Theoretical Physics, Budapest University of Technology and Economics, 1111 Budapest, Budafoki út 8, Hungary.
authors.forename: M
authors.initials: M
authors.lastname: Kormos
authors.affiliation: MTA-BME "Momentum" Exotic Quantum Phases Research Group, Department of Theoretical Physics, Budapest University of Technology and Economics, 1111 Budapest, Budafoki út 8, Hungary.
authors.forename: G
authors.initials: G
authors.lastname: Zaránd
authors.affiliation: MTA-BME "Momentum" Statistical Field Theory Research Group, Department of Theoretical Physics, Budapest University of Technology and Economics, 1111 Budapest, Budafoki út 8, Hungary.
authors.forename: G
authors.initials: G
authors.lastname: Takács