Applicability of the generalized Gibbs ensemble after a quench in the quantum Ising chain

Understand

We investigate the out-of-equilibrium dynamics of the one-dimensional quantum Ising model after a sudden quench of the transverse magnetic field.

• While for a translationally invariant system the statistical description of the asymptotic order parameter correlations after the quench can be performed in terms of the generalized Gibbs ensemble, we show that a breaking of translational invariance, e.g., by perturbing the boundary conditions, disrupts its validity.
• This effect, which of course vanishes in the thermodynamic limit, is shown to be very important in the presence of disorder.