Resonant Tunneling and Coulomb Oscillations

TL;DR

This paper investigates how quantum fluctuations affect electron transport in small metallic islands with Coulomb blockade, revealing their impact on conductance and the importance of higher order processes.

Contribution

It introduces a path integral real-time approach to systematically classify quantum fluctuation effects beyond perturbation in Coulomb blockade systems.

Findings

Quantum fluctuations renormalize system parameters.

Finite lifetime broadening is observed.

Quantum effects are detectable above thermal fluctuations.

Abstract

The influence of quantum fluctuations on electron transport through small metallic islands with Coulomb blockade effects is studied beyond the perturbative regime. In tunnel junctions with low resistance higher order coherent processes and ``inelastic resonant tunneling'' become important. We present a path integral real-time description, which allows a systematic diagrammatic classification of these processes. Quantum fluctuations renormalize system parameters and lead to finite lifetime broadening. Both effects are observable in the gate voltage dependence of the nonlinear conductance. The finite bias voltage introduces an energy scale up to which quantum fluctuations are probed. It can be larger than the temperature, which makes quantum effects experimentally observable above thermal fluctuations.