Bose stimulated dynamics of an atom-molecule superfluid

The recent observations [1,2] of a stable molecular condensate emerging from a condensate of bosonic atoms and related “super-chemical” dynamics have raised an intriguing set of questions. Here we provide a microscopic theory of these phenomena showing one essential feature of these experiments is the extreme narrowness of the Feshbach resonance at B=19.849G in 133Cs. Comparing theory and experiment we demonstrate [3] how this narrow resonance enables the creation of a large fraction of closed-channel molecules in post-quench dynamics, appearing in the vicinity of unitarity. The inclusion of atom-molecule correlations is shown to lead to a substantial fraction of non-condensed closed-channel molecules, which participate in coherent oscillations along with the atomic and molecular condensates, as well as the excited Cooper pairs of atoms in the steady state. Using the time-resolved momentum distribution of atoms and molecules, we contrast this prethermal dynamics with that reported by Makotyn et al [Nat. Phys. 10, 116 (2014)] and Eigen et al [Nature 563, 221 (2018)] at unitarity showing new, resolvable oscillations.

Ref. [1]: Zhendong Zhang, Liangchao Chen, Kai-Xuan Yao, and Cheng

Chin, Nature 592, 708 (2021).

Ref. [2]: Zhendong Zhang, Shu Nagata, Kai-Xuan Yao, and Cheng Chin,

Nature Physics 19, 1466 (2023).

Ref. [3]: Zhiqiang Wang, Ke Wang, Zhendong Zhang, Shu Nagata, Cheng

Chin, K. Levin, arXiv:2310.01639 (2023)