QUANTUM DECOHERENCE IN DISORDERED MESOSCOPIC SYSTEMS

We point out that the low temperature saturation of the electron phase decoherence time in a disordered conductor can be explained within th e existing theory of weak localization provided the effect of quantum thigh frequency) fluctuations is taken into account. Making use of the fluctuation-dissipation theorem we evaluate the quantum decoherence t ime, the crossover temperature below which thermal effects become unim portant, and the weak localization correction delta sigma at T = 0. Fo r 1D systems the latter is found to be delta sigma/sigma proportional to 1/root N, where N is the number of conducting channels.