Nonequilibrium configuration interaction method for transport in correlated quantum systems

TL;DR

This paper introduces a novel nonequilibrium configuration interaction method for modeling transport in correlated quantum systems, leveraging superoperator techniques and quasiparticle excitations to accurately compute steady-state currents.

Contribution

It develops a nonperturbative approach based on configuration interaction theory for nonequilibrium quantum transport, including an exact master equation and a truncated quasiparticle expansion.

Findings

Successfully computes steady-state current in electron-phonon systems

Proves the current conserving property of the method

Demonstrates accuracy through comparison with other approaches

Abstract

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