Quantum quenches from excited states in the Ising chain

Understand

We consider the non-equilibrium dynamics after a sudden quench of the magnetic field in the transverse field Ising chain starting from excited states of the pre-quench Hamiltonian.

• We prove that stationary values of local correlation functions can be described by the generalised Gibbs ensemble (GGE).
• Then we study the full time evolution of the transverse magnetisation by means of stationary phase methods.
• The equal time two-point longitudinal correlation function is analytically derived for a particular class of excited states for quenches within the ferromagnetic phase, and studied numerically in general.