Momentum-Space Josephson Effects

TL;DR

This paper introduces a novel momentum-space Josephson junction in a spin-orbit coupled Bose-Einstein condensate, demonstrating phase-controlled supercurrents and interactions, with potential for quantum circuit applications.

Contribution

It proposes and analyzes the first momentum-space Josephson junction in a spin-orbit coupled BEC, highlighting phase control and interaction effects.

Findings

Josephson currents can be driven by tunneling phase tuning.

Interactions significantly influence the Josephson dynamics.

The scheme enables experimental realization of momentum-space Josephson effects.

Abstract

The Josephson effect is a prominent phenomenon of quantum supercurrents that has been widely studied in superconductors and superfluids. Typical Josephson junctions consist of two real-space superconductors (superfluids) coupled through a weak tunneling barrier. Here we propose a momentum-space Josephson junction in a spin-orbit coupled Bose-Einstein condensate, where states with two diffferent momenta are coupled through Raman-assisted tunneling. We show that Josephson currents can be induced not only by applying the equivalent of "voltages", but also by tuning tunneling phases. Such tunneling-phase-driven Josephson junctions in momentum space are characterized through both full mean field analysis and a concise two-level model, demonstrating the important role of interactions between atoms. Our scheme provides a platform for experimentally realizing momentum-space Josephson junctions and exploring their applications in quantum-mechanical circuits.