Transport Through Nanostructures with Asymmetric Coupling to the Leads

TL;DR

This paper models quantum transport through nanostructures with asymmetric coupling, revealing how system openness and asymmetry influence transmission, resonance behavior, and the transition to super-radiant regimes, with extensions to disorder and higher dimensions.

Contribution

It introduces a non-Hermitian Hamiltonian approach to analyze asymmetric quantum transport, highlighting the sensitivity of transmission to system parameters and identifying super-radiant transitions.

Findings

Transport is highly sensitive to system opening and asymmetry.

Maximum transmission occurs at specific parameters.

A double transition to super-radiance significantly alters resonances.

Abstract

Using an approach to open quantum systems based on the effective non-Hermitian Hamiltonian, we fully describe transport properties for a paradigmatic model of a coherent quantum transmitter: a finite sequence of square potential barriers. We consider the general case of asymmetric external barriers and variable coupling strength to the environment. We demonstrate that transport properties are very sensitive to the degree of opening of the system and determine the parameters for maximum transmission at any given degree of asymmetry. Analyzing the complex eigenvalues of the non-Hermitian Hamiltonian, we show a double transition to a super-radiant regime where the transport properties and the structure of resonances undergo a strong change. We extend our analysis to the presence of disorder and to higher dimensions.