Time and temperature dependence of optical linewidths in glasses at low temperature: Spectral diffusion

The standard theoretical model of two-level systems in low-temperature glasses is modified so that the temperature dependence of the effective homogeneous optical linewidth is in agreement with experiment. This alters the time dependence of the width due to spectral diffusion. The new results fit recent experiments without the need for gaps in the distribution function of flip rates of the two-level-systems or the addition of extra distribution functions. (C) 1996 American Institute of Physics.