Effects of Parity and Symmetry on the Aharonov-Bohm Phase of a Quantum Ring.

Rousan Debbarma,Calle Janlén Stenberg,Claes Thelander,Sebastian Lehmann,Kimberly Dick,Athanasios Tsintzis,Martin Leijnse,Heidi Potts

doi:10.1021/acs.nanolett.1c03882

Abstract

We experimentally investigate the properties of one-dimensional quantum rings that form near the surface of nanowire quantum dots. In agreement with theoretical predictions, we observe the appearance of forbidden gaps in the evolution of states in a magnetic field as the symmetry of a quantum ring is reduced. For a twofold symmetry, our experiments confirm that orbital states are grouped pairwise. Here, a π-phase shift can be introduced in the Aharonov–Bohm relation by controlling the relative orbital parity using an electric field. Studying rings with higher symmetry, we note exceptionally large orbital contributions to the effective g-factor (up to 300), which are many times higher than those previously reported. These findings show that the properties of a phase-coherent system can be significantly altered by the nanostructure symmetry and its interplay with wave function parity.

Highlights

We experimentally investigate the properties of onedimensional quantum rings that form near the surface of nanowire quantum dots
300), which are many times higher than those previously reported. These findings show that the properties of a phase-coherent system can be significantly altered by the nanostructure symmetry and its interplay with wave function parity
In a number of theoretical works on semiconductorbased quantum rings, it was shown that a reduction in the symmetry of a ring results in states undergoing avoided crossings as a function of the magnetic field, leading to energy gaps in the spectrum.[14−21] In essence, a system with an n-fold rotational symmetry of the confinement potential should show orbital states in groups of n separated by gaps close to which the orbital angular momentum approaches zero.[15]

Summary

Introduction

We experimentally investigate the properties of onedimensional quantum rings that form near the surface of nanowire quantum dots. Under a varying magnetic field (B), a phase-coherent quantum ring displays the Aharonov−Bohm (AB) effect,[4] where states with different angular momentum signs periodically cross in energy with the enclosed flux.

Results

Conclusion