Dissipative Superfluidity in a Molecular Bose-Einstein Condensate

Quantum gases of dipolar molecules, which serve as a platform to realize clean and controllable long-range interacting systems, have received considerable attention in the fields of many-body physics and quantum simulation. However, heteronuclear molecules inevitably suffer the two-body loss due to chemical reactions, which is particularly serious for bosonic molecules. Recently, with the development of microwave shielding the first experimental realization of a BEC of heteronuclear molecules has been reported. Thus, it is of fundamental interest to understand whether or not superfluidity exists under two-body loss in such BECs, since dissipation may deteriorate the phase coherence of a superfluid. In this study, we develop superfluid transport theory for a dissipative BEC to show that a weak uniform two-body loss can induce phase rigidity, leading to superfluid transport of bosons even without repulsive interparticle interactions. We also show a generalized f-sum rule for a dissipative superfluid as a consequence of weak U(1) symmetry. Finally, we demonstrate that dissipation enhances the stability of a molecular BEC with dipolar interactions.