Model for phase breaking in the electronic conduction in mesoscopic systems

We study the problem of electronic conduction in mesoscopic systems when th e electrons are allowed to interact not only with static impurities, but al so with a scatterer [a phase breaker (PB)] that possesses internal decrees of freedom. We first analyze the role of the PB in reducing the coherent in terference effects in a one-electron quantum-mechanical system. In the many -electron system we can make a number of quite general statements within th e framework of linear-response theory and the random-phase approximation. W e cannot calculate the conductivity tensor in full generality: we thus reso rt to a model in which that tensor can be expressed entirely in a single-el ectron picture. The resulting conductance is a bilinear expression in the s ingle-electron transmission matrix, containing an additional trace over the states of the PB.