Phase tunable Josephson junction and spontaneous mass current in a spin-orbit coupled Fermi superfluid

TL;DR

This paper demonstrates a phase tunable Josephson junction in a spin-orbit coupled cold atomic gas, showing how magnetic barriers induce spontaneous mass currents and enabling new quantum device functionalities.

Contribution

It introduces a method to realize a tunable phase Josephson junction in cold atoms with magnetic barriers, expanding control over superfluid phase differences.

Findings

Implementation of a phase tunable JJ in cold atomic gases.

Observation of spontaneous mass currents induced by magnetic barriers.

Demonstration of magnetoelectric effects in cold atom systems.

Abstract

Atomtronics has the potential for engineering new types of functional devices, such as Josephson junctions (JJs). Previous studies have mainly focused on JJs whose ground states have 0 or $\pi $ superconducting phase difference across the junctions, while arbitrarily tunable phase JJs may have important applications in superconducting electronics and quantum computation. Here we show that a phase tunable JJ can be implemented in a spin-orbit coupled cold atomic gas with the magnetic tunneling barrier generated by a spin-dependent focused laser beam. We consider the JJ confined in either a linear harmonic trap or a circular ring trap. In the ring trap, the magnetic barrier induces a spontaneous mass current for the ground state of the JJ, demonstrating the magnetoelectric effects of cold atoms.