Pair-tunneling resonance in the single-electron transport regime

TL;DR

This paper predicts a novel electron pair-tunneling resonance in quantum dots with positive charging energies, which can be mistaken for weak single-electron resonances, providing crucial insights for interpreting transport spectroscopy data.

Contribution

It introduces the concept of pair-tunneling resonance in the single-electron transport regime and analyzes its characteristics and distinctions from inelastic cotunneling.

Findings

Identifies a new pair-tunneling resonance in quantum dot transport.

Provides analytic peak shape and dependencies on temperature, magnetic field, and asymmetry.

Highlights potential misinterpretation of experimental data due to this resonance.

Abstract

We predict a new electron pair-tunneling (PT) resonance in non-linear transport through quantum dots with positive charging energies exceeding the broadening due to thermal and quantum fluctuations. The PT resonance shows up in the single-electron transport (SET) regime as a peak in the derivative of the non-linear conductance when the electrochemical potential of one electrode matches the average of two subsequent charge addition energies. For a single level quantum dot (Anderson model) we find the analytic peak shape and the dependence on temperature, magnetic field and junction asymmetry and compare with the inelastic cotunneling peak which is of the same order of magnitude. In experimental transport data the PT resonance may be mistaken for a weak SET resonance judging only by the voltage dependence of its position. Our results provide essential clues to avoid such erroneous interpretation of transport spectroscopy data.