On steady-state currents through nano-devices: a scattering-states numerical renormalization group approach to open quantum systems

TL;DR

This paper introduces a numerical renormalization group method for calculating steady-state currents in nano-devices, accurately capturing boundary conditions and electron dynamics in open quantum systems.

Contribution

It develops a novel NRG approach using scattering states and Wilson chains to model steady-state transport in nano-devices under bias.

Findings

Accurate calculation of temperature-dependent current versus bias voltage.

Effective modeling of open quantum systems with boundary conditions.

Application to magnetic field effects in nano-device transport.

Abstract

We propose a numerical renormalization group (NRG) approach to steady-state currents through nano-devices. A discretization of the scattering-states continuum ensures the correct boundary condition for an open quantum system. We introduce two degenerate Wilson chains for current carrying left and right-moving electrons reflecting time-reversal symmetry in the absence of a finite bias $V$. We employ the time-dependent NRG to evolve the known steady-state density operator for a non-interacting junction into the density operator of the fully interacting nano-device at finite bias. We calculate the temperature dependent current as function of $V$ and applied external magnetic field using a recently developed algorithm for non-equilibrium spectral functions.