Geometric phase driven Josephson junction: Possible experimental scheme for the search of spin superfluidity

TL;DR

This paper investigates how a rotating magnetic field can induce oscillatory spin currents in a Josephson junction between spin-1 Bose-Einstein condensates, proposing an experimental setup to explore spin superfluidity.

Contribution

It introduces a novel scheme using geometric phases and magnetic field modulation to generate and analyze spin supercurrents in Bose-Einstein condensate junctions.

Findings

Oscillatory spin current driven by geometric phase in low-frequency limit.

Distinct high-frequency regime with Zeeman energy difference causing spin oscillations.

Analytical and numerical results support potential experimental realization.

Abstract

We use the Gross-Pitaevskii equation to study Josephson tunneling between two weakly coupled Bose-Einstein condensates, which compose spin-1 bosons. We show that a rotating magnetic field on one side can produce a phase difference across the junction, resulting in an oscillatory tunneling spin current. Besides numerical calculation, we derive analytical results in two extreme cases, namely the low- and high-frequency limits: in the low-frequency limit (magnetic field rotates adiabatically), a non-Abelian geometric phase arises and leads to the oscillatory spin current. By sharp contrast, the physics is intrinsically different in the high-frequency limit, where an average Zeeman energy difference leads to an oscillatory spin current. This proposed apparatus should be promising for the future experimental search of spin superfluidity.