Interaction and Quantum Decoherence
  We discuss a fundamental effect of the interaction-induced decoherence of the electron wave function in disordered metals. In the first part of the paper we consider a simple model of a quantum particle interacting with a bath of harmonic oscillators and analyze the physical origin of the effect. This exactly solvable model also allows to understand why the arguments against the existence of the effect at low temperatures fail. The second part of the paper is devoted to a rigorous analysis of quantum decoherence in disordered metals. We also discuss the relation of our results to the recent experiments on GaAs structures. The existence of a finite quantum decoherence rate at low $T$ implies that low dimensional disordered metals with generic parameters do not become insulators even at T=0. 
D.S. Golubev and A.D. Zaikin