  We study the nonequilibrium dynamics of the Quantum Ising Model following an
abrupt quench of the transverse field. We focus on the on-site autocorrelation
function of the order parameter, and extract the phase coherence time
$\tau^{\phi}_Q$ from its asymptotic behavior. We show that the initial state
determines $\tau^{\phi}_Q$ only through an effective temperature set by its
energy and the final Hamiltonian. Moreover, we observe that the dependence of
$\tau^{\phi}_Q$ on the effective temperature fairly agrees with that obtained
in thermal equilibrium as a function of the equilibrium temperature.
