Quantum Quench in the Transverse Field Ising Chain

I discuss the time evolution of observables in many-particle systems after a quantum quench, i.e. the sudden change of a parameter characterizing the Hamiltonian. I focus on the case of one dimensional systems, where recent experiments on cold atomic gases have found very unusual behaviour. I show that for the example of the transverse field Ising chain the behaviour of the system at late times after the quench can be understood in terms of a stationary state that is described by a "generalized Gibbs ensemble".