Atom-molecule dark states in a Bose-Einstein condensate

TL;DR

This paper reports the creation of a dark quantum superposition state between a Bose-Einstein condensate of rubidium atoms and ground state rubidium molecules, demonstrating suppression of photoassociation loss and advancing control over atom-molecule quantum states.

Contribution

It introduces a method to generate and observe atom-molecule dark states in a BEC using two-color photoassociation, with experimental results matching a simple three mode model.

Findings

Observation of a dark superposition state suppressing photoassociation loss

Limited molecule population due to laser-induced decay

Experimental results align with theoretical three mode model

Abstract

We have created a dark quantum superposition state of a Rb Bose-Einstein condensate (BEC) and a degenerate gas of Rb$_2$ ground state molecules in a specific ro-vibrational state using two-color photoassociation. As a signature for the decoupling of this coherent atom-molecule gas from the light field we observe a striking suppression of photoassociation loss. In our experiment the maximal molecule population in the dark state is limited to about 100 Rb$_2$ molecules due to laser induced decay. The experimental findings can be well described by a simple three mode model.