Quantum Decoherence and Weak Localization at Low Temperatures

TL;DR

This paper develops a theoretical framework for understanding how electron interactions cause decoherence in disordered metals at low temperatures, challenging the notion of strong localization.

Contribution

It introduces a formal exact equation of motion for the electron density matrix considering interactions, highlighting quantum noise as a decoherence mechanism at T=0.

Findings

Quantum noise induces decoherence at zero temperature.

Interaction effects are equivalent to an effective dissipative environment.

Results question the existence of strong localization in low-dimensional disordered metals.

Abstract

We develope a theory of a fundamental effect of the interaction-induced decoherence of the electron wave function in a disordered metal. With the aid of the Keldysh technique and the path integral formalism we derive a formally exact equation of motion for the electron density matrix in the presence of interaction. We demonstrate that the effect of interaction of the electron with other electrons and lattice ions in a disordered metal is equivalent to that of an effective dissipative environment. Quantum noise of this environment causes quantum decoherence even at T=0. Our analysis explicitely accounts for the Pauli principle which plays an important role for inelastic scattering processes but turns out not to affect quantum decoherence. Our results seriously challenge the existence of strong localization in low dimensional disordered metals.