Non-Equilibrium Dynamics and Superfluid Ring Excitations in Binary Bose-Einstein Condensates

TL;DR

This study investigates non-equilibrium dynamics in binary Bose-Einstein condensates, revealing persistent oscillating ring structures and demonstrating strong agreement between experimental observations and a detailed theoretical mean-field model.

Contribution

It provides new insights into non-equilibrium component separation dynamics and introduces a refined multi-component mean-field model including atomic losses and precise trap characterization.

Findings

Observation of non-damped, oscillating ring-like structures during component separation

Quantitative agreement between experimental data and theoretical simulations

Enhanced understanding of collective excitations in binary superfluids

Abstract

We revisit a classic study [D. S. Hall {\it et al.}, Phys. Rev. Lett. {\bf 81}, 1539 (1998)] of interpenetrating Bose-Einstein condensates in the hyperfine states $\ket{F = 1, m_f = -1}\equiv\ket{1}$ and $\ket{F = 2, m_f = +1}\equiv\ket{2}$ of ${}^{87}$Rb and observe striking new non-equilibrium component separation dynamics in the form of oscillating ring-like structures. The process of component separation is not significantly damped, a finding that also contrasts sharply with earlier experimental work, allowing a clean first look at a collective excitation of a binary superfluid. We further demonstrate extraordinary quantitative agreement between theoretical and experimental results using a multi-component mean-field model with key additional features: the inclusion of atomic losses and the careful characterization of trap potentials (at the level of a fraction of a percent).