Transient current in a quantum dot asymmetrically coupled to metallic leads

TL;DR

This paper investigates how asymmetric coupling in a quantum dot affects transient current behavior, revealing oscillations caused by lead density of states that persist longer than charge fluctuations and depend on temperature and bias.

Contribution

It introduces a detailed analysis of transient current oscillations in asymmetric quantum dots using the non-crossing approximation, highlighting their microscopic origin and experimental relevance.

Findings

Oscillations in current are induced by sharp features in lead density of states.

Oscillations persist longer than charge fluctuation timescales.

Amplitude of oscillations increases with decreasing temperature or bias, saturating below the Kondo temperature.

Abstract

The time-dependent non-crossing approximation is used to study the transient current in a single electron transistor attached asymmetrically to two leads following a sudden change in the energy of the dot level. We show that for asymmetric coupling, sharp features in the density of states of the leads can induce oscillations in the current through the dot. These oscillations persist to much longer timescales than the timescale for charge fluctuations. The amplitude of the oscillations increases as the temperature or source-drain bias across the dot is reduced and saturates for values below the Kondo temperature. We discuss the microscopic origin of these oscillations and comment on the possibility for their experimental detection.