Transmission through Quantum Dots: Focus on Phase Lapses

TL;DR

This paper explains the phenomenon of phase lapses in quantum dot transmission by analyzing the effects of asymmetric coupling and population switching, linking it to fundamental spectral properties.

Contribution

It demonstrates that phase lapses are a generic feature caused by asymmetric coupling and population switching, supported by spectral shift function analysis.

Findings

Phase lapses are linked to asymmetric dot-lead coupling.

Population switching causes systematic phase lapses.

Spectral shift function relates phase lapses to Friedel sum rule.

Abstract

Measurements of the transmission phase in transport through a quantum dot embedded in an Aharonov-Bohm interferometer show systematic sequences of phase lapses separated by Coulomb peaks. Using a two-level quantum dot as an example we show that this phenomenon can be accounted for by the combined effect of asymmetric dot-lead coupling and interaction-induced "population switching" of the levels, rendering this behavior generic. In addition, we use the notion of spectral shift function to analyze the relationship between transmission phase lapses and the Friedel sum rule.