Quantum Quench in the Transverse Field Ising Chain II: Stationary State   Properties
  We consider the stationary state properties of the reduced density matrix as well as spin-spin correlation functions after a sudden quantum quench of the magnetic field in the transverse field Ising chain. We demonstrate that stationary state properties are described by a generalized Gibbs ensemble. We discuss the approach to the stationary state at late times. 
Pasquale Calabrese, Fabian H.L. Essler, and Maurizio Fagotti
cond-mat.stat-mech math-ph math.MP quant-ph