Spectral diffusion decay of spontaneous echoes in disordered systems

Abstract
In a system of two level systems or 1/ 2 spins, the relaxation of spontaneous echoes is obtained in the framework of the Klauder-Anderson scheme. The assumption of a hyperbolic distribution relaxation times T1 (or « 1/f noise ») leads to a general relaxation law : exp(— γ Tτ) where T is the temperature, τ the delay time between the two pulses and γ a coefficient depending only on the average interaction between the thermally excited two level systems