Nonequilibrium configuration interaction method for transport in correlated quantum systems

Abstract

We present a new approach to treat correlations in nonequilibrium quantum\nmany-particle system. The method is based on ideas of configuration interaction\ntheory of exact nonperturbative ground state electronic structure calculations.\nWe use superoperator techniques in Liouville-Fock space and represent the\nnonequilibrium density matrix as a linear combination of all possible\nnonequilibrium quasiparticle excitations built on the appropriate reference\nstate. As an example we consider the electron transport through the system with\nelectron-phonon interaction. The concept of embedding (buffer zones between the\nreservoirs and the correlated quantum system) is used to derive an exact master\nequation for the reduced density matrix. Using approximate (truncated)\nexpansion of the trial density matrix we obtain the linear system of equations\nfor two-quasiparticle amplitudes. Then we compute the steady-state current and\ncompare the result with other approaches. The current conserving property of\nthe method is proved.\n