The cross-over from Townes solitons to droplets in a 2D Bose mixture

Year: 2023

Authors: Bakkali-Hassani B.; Maury C.; Stringari S.; Nascimbene S.; Dalibard J.; Beugnon J.

Autors Affiliation: Laboratoire Kastler Brossel, Collige de France, CNRS, ENS-PSL University, Sorbonne University, 11 Place Marcelin Berthelot, 75005 Paris, France; Pitaevskii BEC Center, CNR-INO and Dipartimento di Fisica, Universit?a di Trento, Trento 38123, Italy; Trento Institute for Fundamental Physics and Applications, INFN

Abstract: When two Bose-Einstein condensates-labelled 1 and 2-overlap spatially, the equilibrium state of the system depends on the miscibility criterion for the two fluids. Here, we theoretically focus on the non-miscible regime in two spatial dimensions and explore the properties of the localized wave packet formed by the minority component 2 when immersed in an infinite bath formed by component 1. We address the zero-temperature regime and describe the two-fluid system by coupled classical field equations. We show that such a wave packet exists only for an atom number N (2) above a threshold value corresponding to the Townes soliton state. We identify the regimes where this localized state can be described by an effective single-field equation up to the droplet case, where component 2 behaves like an incompressible fluid. We study the near-equilibrium dynamics of the coupled fluids, which reveals specific parameter ranges for the existence of localized excitation modes.


Volume: 25 (1)      Pages from: 013007-1  to: 013007-13

KeyWords: Townes soliton; quantum gas mixtures; self-evaporation; excitation modes; droplets
DOI: 10.1088/1367-2630/acaee3