NOVEL MECHANISM OF TRANSVERSE RELAXATION IN GLASSES AT ULTRA-LOW TEMPERATURES

A novel dephasing mechanism in dielectric crystals is considered. The mechanism is due to the delocalized collective excitations arising in the system of interacting two-level systems (TLS). The spectral diffus ion induced by these excitations gives rise to the transverse relaxati on which is independent of phonons. The mechanism results in linear te mperature dependence of the dephasing rate and becomes predominant at ultra low temperatures. A qualitative agreement with the experimental data is found. (C) 1998 Elsevier Science B.V. All rights reserved.