Magnetic field dependent transmission phase of a double dot system in a quantum ring

TL;DR

This study investigates how the transmission phase in a quantum ring with two quantum dots varies with magnetic field, revealing unexpected dependencies and phase lapses, advancing understanding of quantum interference effects.

Contribution

It provides experimental measurements of transmission phase dependence on magnetic field in a double-dot quantum ring, highlighting novel magnetic field effects not fully predicted by existing theories.

Findings

Phase shifts align qualitatively with theory

Phase lapses occur only at specific magnetic fields

Unexpected magnetic field dependence observed

Abstract

The Aharonov-Bohm effect is measured in a four-terminal open ring geometry based on a Ga[Al]As heterostructure. Two quantum dots are embedded in the structure, one in each of the two interfering paths. The number of electrons in the two dots can be controlled independently. The transmission phase is measured as electrons are added to or taken away from the individual quantum dots. Although the measured phase shifts are in qualitative agreement with theoretical predictions, the phase evolution exhibits unexpected dependence on the magnetic field. For example, phase lapses are found only in certain ranges of magnetic field.