Interference and shot noise in a degenerate Anderson-Holstein model

TL;DR

This paper investigates how interference effects and electron-vibron interactions in a degenerate Anderson-Holstein model influence transport properties, revealing complex conductance patterns and shot noise enhancements.

Contribution

It introduces a detailed analysis of interference and vibronic effects in a degenerate Anderson-Holstein model, highlighting the impact on transport and shot noise without coupling asymmetry.

Findings

Destructive interference causes positive and negative differential conductance.

Shot noise is significantly enhanced due to interference effects.

Lamb-shift renormalization critically influences transport characteristics.

Abstract

We study the transport properties of an Anderson-Holstein model with orbital degeneracies and a tunneling phase that allows for the formation of dark states. The resulting destructive interference yields a characteristic pattern of positive and negative differential conductance features with enhanced shot noise, without further asymmetry requirements in the coupling to the leads. The transport characteristics are strongly influenced by the Lamb-shift renormalization of the system Hamiltonian. Thus, the electron-vibron coupling cannot be extracted by a simple fit of the current steps to a Poisson distribution. For strong vibronic relaxation, a simpler effective model with analytical solution allows for a better understanding and moreover demonstrates the robustness of the described effects.