Josephson effect and quantum merging of two Bose superfluids

TL;DR

This paper demonstrates that two initially independent Bose superfluids can exhibit the Josephson effect when weakly connected, due to quantum merging facilitated by interparticle interactions, confirmed through analysis of the one-particle density matrix.

Contribution

It introduces an effective order parameter for the combined system, showing Josephson effect emergence in independent Bose superfluids, advancing understanding of superfluid quantum merging.

Findings

Josephson effect occurs between independent Bose superfluids.

The one-particle density matrix can be factorized under interactions.

An effective order parameter describes the merged superfluid state.

Abstract

We consider the Josephson effect when two independent Bose superfluids are weakly connected. In the presence of interparticle interaction and based on the calculations of the one-particle density matrix of the whole system, we find that the one-particle density matrix can be factorized which satisfies the general criterion of Bose superfluid proposed by Penrose and Onsager. By introducing an effective order parameter for the whole system, our researches show that there is Josephson effect for two independent Bose superfluids.