Observation of two-species vortex lattices in a mixture of mass-imbalance Bose and Fermi superfluids

TL;DR

This paper reports the first direct visual evidence of two-species superfluidity in a mass-imbalanced Bose-Fermi mixture of lithium-6 and potassium-41, demonstrated through vortex lattices and interaction effects.

Contribution

It presents the realization of a mass-imbalanced Bose-Fermi superfluid with visual proof of superfluidity via vortex lattices and studies inter-species interaction effects.

Findings

Observation of vortex lattices in both species confirming superfluidity.

Pronounced inter-species interaction effects on vortex formation and decay.

Establishment of a new platform for studying quantum phenomena in mixed superfluids.

Abstract

The superfluid mixture of interacting Bose and Fermi species is a remarkable many-body quantum system. Dilute degenerate atomic gases, especially for two species of distinct masses, are excellent candidates for exploring fundamental features of superfluid mixture. However, producing a mass-imbalance Bose-Fermi superfluid mixture, providing an unambiguous visual proof of two-species superfluidity and probing inter-species interaction effects remain challenging. Here, we report the realization of a two-species superfluid of lithium-6 and potassium-41. By rotating the dilute gases, we observe the simultaneous existence of vortex lattices in both species, and thus present a definitive visual evidence for the simultaneous superfluidity of the two species. Pronounced effects of the inter-species interaction are demonstrated through a series of precision measurements on the formation and decay of two-species vortices. Our system provides a new platform for studying novel macroscopic quantum phenomena in vortex matter of interacting species.