# Mixture of two unequally charged superfluids in a magnetic field

## TL;DR

This paper studies how mixtures of two superfluids with different synthetic charges in a ring trap respond to artificial magnetic fields, revealing angular momentum transfer, persistent currents, and stability conditions influenced by inter-fluid interactions.

## Contribution

It introduces a detailed analysis of unequal charged superfluid mixtures under artificial magnetic fields, highlighting angular momentum transfer and persistent current phenomena.

## Key findings

- Unequal synthetic charges cause different angular momentum distributions.
- Inter-fluid interactions enable angular momentum transfer and counter flows.
- Persistent currents can be induced even in uncharged superfluids.

## Abstract

The artificial magnetic fields engineered for ultra cold gases depend on the internal structure of the neutral atoms. Therefore the components of a mixture composed of two atomic gases can exhibit a different response to an artificial magnetic field. Such a mixture can be interpreted as a mixture of two atomic gases, carrying different synthetic charges. In this article, we consider such mixtures of two superfluids with unequal synthetic charges in a ring trap subject to a uniform artificial magnetic field. The charge imbalance in such a mixture changes the distribution of excited particles over angular momentum states compared to that of an equally charged mixture. This microscopic difference exhibits macroscopic consequences; such as the occurrence of an angular momentum transfer between two unequally charged components. Due to the inter-fluid atomic interactions in a ring, the angular momentum transfer can create a counter flowing persistent current in the weakly charged superfluid. Even in the limiting case of a charged and an uncharged superfluid mixture, a persistent current can be induced in the uncharged superfluid, despite the fact that it is not directly coupled to the magnetic field. The stability analysis shows that the induction depends on the interplay between inter-fluid interaction and the applied magnetic field. We obtain instability boundaries of the system and construct phase diagrams as a function of the inter-fluid interaction and the magnetic field. We investigate these properties employing the Bogoliubov approximation.