Photon-assisted tunneling resonantly controlling spin current of a spin-orbit-coupled atom in a toroidal trap

TL;DR

This paper demonstrates how photon-assisted tunneling via a flashing ring-shaped potential can generate and control tunable AC spin and atomic currents in a spin-orbit-coupled Bose-Einstein condensate, with potential for precise spin dynamics manipulation.

Contribution

It introduces a novel method using resonant photon-assisted tunneling to control spin and atomic currents in SO-coupled BECs, including net spin current without mass flow.

Findings

Tunable AC spin and atomic currents can be generated and controlled.

Resonance phenomena are analytically described by a simple three-level model.

Net AC spin current can be achieved without accompanying mass current.

Abstract

The periodic flashing potential has proven to be a powerful tool for investigating directed atomic currents. By applying the flashing ring-shaped potential to spin-orbit (SO) coupled, noninteracting Bose-Einstein condensate (BEC) systems, through photon-assisted tunneling (resonance) techniques, we demonstrate the generation of tunable alternating (AC) spin and atomic mass currents that can be precisely controlled in terms of direction and strength. The underlying mechanism behind this phenomenon is that the flashing potential supplies enough photons to induce Rabi oscillations and provides momentum transfer for spin and atomic transport. As the single-particle ground state of the unperturbed SO-coupled BEC depends on the Raman coupling strength, we demonstrate how to generate and control AC spin currents in the cases where the initial state resides in a single-well or double-well phase. In particular, we realize and explain the mechanism of generating a net AC spin current without mass current through single-photon resonance processes. It is shown that these interesting resonance phenomena can be analytically described only by the simple three-level model, which creates the possibility of transparent controls of spin dynamics.