Quantum Decoherence in Disordered Mesoscopic Systems

TL;DR

This paper explains the low temperature saturation of electron phase decoherence time in disordered conductors by incorporating quantum fluctuations into the weak localization theory, providing quantitative evaluations for various parameters.

Contribution

It demonstrates that quantum (high frequency) fluctuations can account for decoherence saturation, extending the weak localization framework to include quantum effects.

Findings

Quantum fluctuations explain decoherence saturation at low temperatures.

The crossover temperature below which thermal effects are negligible is evaluated.

Weak localization correction in 1D systems scales as 1/√N, with N being the number of channels.

Abstract

We point out that the low temperature saturation of the electron phase decoherence time in a disordered conductor can be explained within the existing theory of weak localization provided the effect of quantum (high frequency) fluctuations is taken into account. Making use of the fluctuation-dissipation theorem we evaluate the quantum decoherence time, the crossover temperature below which thermal effects become unimportant, and the weak localization correction $\delta \sigma$ at T=0. For 1d systems the latter is found to be $\delta \sigma \propto 1/ \sqrt{N}$, where $N$ is the number of conducting channels.