# Interaction modulation in a long-lived Bose-Einstein condensate by rf coupling

## TL;DR

This paper demonstrates how radio-frequency coupling can modulate interactions in a long-lived Bose-Einstein condensate, enabling observation of interaction-driven phenomena and transitions between miscible and immiscible states.

## Contribution

It introduces a method to control effective atomic interactions in a BEC using rf coupling, allowing long-term evolution studies without inelastic losses.

## Key findings

- Rf coupling alters the density distribution reflecting interaction changes.
- A miscibility-to-immiscibility transition is achieved by quenching the rf field.
- Long-lived states facilitate out-of-equilibrium quantum system studies.

## Abstract

We demonstrate modulation of the effective interaction between the magnetic sublevels of the hyperfine spin $F=1$ in a $^{87}$Rb Bose-Einstein condensate by Rabi coupling with radio-frequency (rf) field. The use of the $F=1$ manifold enables us to observe the long-term evolution of the system owing to the absence of inelastic collisional losses. We observe that the evolution of the density distribution reflects the change in the effective interaction between atoms due to rf coupling. We also realize a miscibility-to-immiscibility transition in the magnetic sublevels of $m = \pm 1$ by quenching the rf field. Rf-induced interaction modulation in long-lived states as demonstrated here will facilitate the study of out-of-equilibrium quantum systems.