DIFFUSION OF A HEAVY PARTICLE IN A FERMI-LIQUID THEORY

This article reviews the recent work in quantum diffusion of particles interacting with the Fermi-liquid environment. Two distinct problems discussed are: (a) the dynamics of a heavy particle in a homogeneous Fermi-liquid (which is the case of ion motion in normal liquid 3 He ) and (b) the tunneling diffusion of particles in metals in the presence of strong crystal potential. Attention is given to the strong interaction effects which in most cases lead to the particle quasilocalization (localization) and destroy the coherent propagation of particles down to extremely low temperatures. The overdamped particle motion, mass renormalization and fermionic polaron effect are discussed in detail. Some attention is also given to the experimental investigations in this field, concentrating particularly on ion mobility in 3 He and muon (hydrogen) diffusion in metals.