Which phase is measured in the mesoscopic Aharonov-Bohm interferometer?

TL;DR

This paper investigates the phase measurement in mesoscopic Aharonov-Bohm interferometers, clarifying when the measured phase corresponds to the intrinsic quantum transmission phase of a quantum dot.

Contribution

It provides a theoretical model with quantitative criteria for when the measured phase matches the intrinsic quantum dot phase, considering the effects of open and closed interferometer configurations.

Findings

In closed interferometers, the phase only jumps between 0 and π due to Onsager's relations.

Open interferometers' phase depends on the opening details.

Small transmission and reflection in lossy channels near the QD ensure the measured phase equals the intrinsic phase.

Abstract

Mesoscopic solid state Aharonov-Bohm interferometers have been used to measure the "intrinsic" phase, $\alpha_{QD}$, of the resonant quantum transmission amplitude through a quantum dot (QD). For a two-terminal "closed" interferometer, which conserves the electron current, Onsager's relations require that the measured phase shift $\beta$ only "jumps" between 0 and $\pi$. Additional terminals open the interferometer but then $\beta$ depends on the details of the opening. Using a theoretical model, we present quantitative criteria (which can be tested experimentally) for $\beta$ to be equal to the desired $\alpha_{QD}$: the "lossy" channels near the QD should have both a small transmission and a small reflection.