High-temperature Aharonov-Bohm effect in transport through a single-channel quantum ring

Abstract

We overview transport properties of an Aharonov-Bohm interferometer made of a single-channel quantum ring. Remarkably, in this setup, essentially quantum effects survive thermal averaging: the high-temperature tunneling conductance G of a ring shows sharp dips (antiresonances) as a function of magnetic flux. We discuss effects of the electron-electron interaction, disorder, and spin-orbit coupling on the Aharonov-Bohm transport through the ring. The interaction splits the dip into series of dips broadened by dephasing. The physics behind this behavior is the persistent-current-blockade: the current through the ring is blocked by the circular current inside the ring. Dephasing is then dominated by tunneling-induced fluctuations of the circular current. The short-range disorder broadens antiresonances, while the long-range one induces additional dips. In the presence of a spin-orbit coupling, G exhibits two types of sharp antiresonances: Aharonov-Bohm and Aharonov-Casher ones. In the vicinity of the antiresonances, the tunneling electrons acquire spin polarization, so that the ring serves as a spin polarizer.