Phase Separation of Multi-Component Bose-Einstein Condensates of Trapped Atoms and Molecules with a Homonuclear Feshbach Resonance

TL;DR

This paper models phase separation in multi-component Bose-Einstein condensates involving atoms and molecules near a Feshbach resonance, revealing how resonance induces different phase separation types and analyzing molecular roles.

Contribution

The study develops a comprehensive model including all interactions and correlation effects, predicting phase structures and molecular influence in BECs with Feshbach resonance.

Findings

Feshbach resonance induces two types of phase separation.

Density profiles vary across atom- and molecule-dominant regimes.

Effective interactions describe molecular roles in the atom-dominant regime.

Abstract

We investigate phase separation of Bose-Einstein condensates (BECs) of two-component atoms and one-component molecules with a homonuclear Feshbach resonance. We develop a full model for dilute atomic and molecular gases including correlation of the Feshbach resonance and all kinds of interparticle interactions, and numerically calculate order parameters of the BECs in spherical harmonic oscillator traps at zero temperature with the Bogoliubov's classical field approximation. As a result, we find out that the Feshbach resonance can induce two types of phase separation. The actual phase structures and density profiles of the trapped gases are predicted in the whole parameter region, from the atom dominant regime to the molecule dominant regime. We focus on the role of the molecules in the phase separation. Especially in the atom dominant regime, the role of the molecules is described through effective interactions derived from our model. Furthermore we show that a perturbative and semi-classical limit of our model reproduces the conventional atomic BEC (single-channel) model.