LOW-TEMPERATURE DYNAMICS IN GLASSES AND THE STOCHASTIC SUDDEN-JUMP MODEL

Non-linear optical experiments in glasses exhibiting spectral diffusion give strong support for the importance of two-level system excitations (TLS). The difference in the line widths measured by these experiments and fast two-pulse photon echo experiments has been ascribed to slowly relaxing TLS. The sudden jump model is found to be an appropriate description of the dynamics; within this model, we derive new analytical results for three-pulse experiments at all temperatures. These experiments and the dynamics of TLS in glasses are discussed within the context of these results.