Correlation echoes in the stochastic excitation of inhomogeneously broadened two-level systems

The third-order cross-correlations between a free induction signal of an inhomogeneously broadened two-level system and white Gaussian noise exciting this system are studied. The temporal properties of the third-order cross-correlation functions are found to correspond to the characteristics of ordinary two-and three-pulse spin and light (photon) echoes excited by determinate radio pulses. The nonlinear properties of correlation echoes are studied as functions of the noise pulse parameters. It is established that the correlation echo amplitude is determined not only by the noise pulse parameters but also by the position on the time axis of the noise counts that form the given type of echo. Finally, the behavior of the spin and light correlation echoes in the appropriate ranges is discussed. Zh. éksp. Teor. Fiz. 112, 63–77 (July 1997)