Co-tunneling assisted sequential tunneling in multi-level quantum dots

TL;DR

This paper studies how co-tunneling assisted sequential tunneling (CAST) influences conductance and shot noise in multi-level quantum dots, revealing that CAST dominates the transition from Coulomb blockade to sequential tunneling and affects noise characteristics.

Contribution

It provides a detailed analysis of CAST processes in multi-level quantum dots, highlighting their impact on conductance and noise, especially the scaling behavior with temperature.

Findings

CAST processes dominate the transition region from Coulomb blockade to sequential tunneling.

The width of CAST features scales only with temperature, not coupling strength.

Shot noise is super-Poissonian at inelastic co-tunneling onset and even stronger above CAST thresholds.

Abstract

We investigate the conductance and zero-frequency shot noise of interacting, multi-level quantum dots coupled to leads. We observe that co-tunneling assisted sequential tunneling (CAST) processes play a dominant role in the transition region from Coulomb blockade to sequential tunneling. We analyze for intermediate coupling strength the dependence of the conductance due to CAST processes on temperature, coupling constant, and gate voltage. Remarkably, the width of the CAST transport feature scales only with temperature, but not with the coupling constant. While the onset of inelastic co-tunneling is associated with a super-Poissonian noise, the noise is even stronger above the threshold for CAST processes