Quantum Transport through Nanostructures with Orbital Degeneracies

TL;DR

This paper investigates quantum transport in nanostructures with near-degenerate orbitals, highlighting the importance of using the singular-coupling limit for accurate master equation derivation, revealing off-diagonal density matrix effects.

Contribution

It introduces the necessity of the singular-coupling limit for modeling transport in nearly degenerate nanostructures, differing from traditional weak-coupling approaches.

Findings

Off-diagonal density matrix elements influence transport signatures.

Singular-coupling limit provides more accurate descriptions of degeneracy effects.

Transport characteristics reflect symmetry-breaking effects in nanostructures.

Abstract

Geometric symmetries cause orbital degeneracies in a molecule's spectrum. In a single-molecule junction, these degeneracies are lifted by various symmetry-breaking effects. We study quantum transport through such nanostructures with an almost degenerate spectrum. We show that the master equation for the reduced density matrix must be derived within the singular-coupling limit as opposed to the conventional weak-coupling limit. This results in signatures of the density matrix's off-diagonal elements in the transport characteristics.