Quantum interference of electrons in a ring: tuning of the geometrical phase

TL;DR

This paper investigates how magnetic and electric fields influence electron conductance oscillations in a mesoscopic ring, revealing tunable geometric phase effects from adiabatic to nonadiabatic regimes, considering realistic device imperfections.

Contribution

It introduces a comprehensive model that captures the interplay of dynamical and geometric phases in conductance oscillations, including effects of disorder and backscattering.

Findings

Conductance oscillations depend on Aharonov-Bohm flux and spin-orbit coupling.

Geometric phase contribution can be tuned from Berry to Aharonov-Anandan regimes.

Disorder and backscattering effects are incorporated into the model.

Abstract

We calculate the oscillations of the DC conductance across a mesoscopic ring, simultaneously tuned by applied magnetic and electric fields orthogonal to the ring. The oscillations depend on the Aharonov-Bohm flux and of the spin-orbit coupling. They result from mixing of the dynamical phase, including the Zeeman spin splitting, and of geometric phases. By changing the applied fields, the geometric phase contribution to the conductance oscillations can be tuned from the adiabatic (Berry) to the nonadiabatic (Ahronov-Anandan) regime. To model a realistic device, we also include nonzero backscattering at the connection between ring and contacts, and a random phase for electron wavefunction, accounting for dephasing due to disorder.