Stability and collapse of a coupled Bose–Einstein condensate

M. B. Sobnack, Fedor Vasilievich Kusmartsev

Zi-Fa Yu, Ai‐Xia Zhang, Rong-An Tang +3 more

We study the stability of a spin-orbit-coupled binary Bose-Einstein condensate. It is known that a trapped binary Bose-Einstein condensate will collapse when the interatomic attraction is beyond the threshold. We demonstrate both analytically and numerically that instead of collapse such a system can be stabilized by spin-orbit coupling and Raman coupling. The stability criteria and stability diagram in full parameter space are presented analytically. The stabilizing mechanism is revealed explicitly: the spin-orbit coupling and Raman coupling generate an effective interatomic repulsion, which changes the stability criteria, neutralizes the mean-field attraction, and stabilizes the system against collapse. Interestingly, the generated effective interatomic repulsion is determined by spin-orbit coupling and Raman coupling. That is, a quantitative theoretical evidence for controlling the stability of the system is provided, which can be realized easily in current experiments.

Marijan Koštrun, Juha Javanainen

We investigate the coupled atom-molecule Bose-Einstein condensate, as would ensue in an attempt to control the scattering length by means of either the Feshbach resonance or coherent photoassociation. In a mean-field model with a photoassociative coupling between the condensates, we demonstrate that the system is structurally stable. The sign of the effective scattering length notwithstanding, neither condensate will collapse.

博史 森瀬

Jacob Roberts, N. R. Claussen, Simon L. Cornish +3 more

Sadhan K. Adhikari

The dynamics of stability and collapse of a trapped atomic Bose-Einstein condensate (BEC) coupled to a molecular one is studied using the time-dependent Gross-Pitaevskii (GP) equation including a nonlinear interaction term which can transform two atoms into a molecule and vice versa. We find an interesting oscillation of the number of atoms and molecules for a BEC of fixed mass. This oscillation is a consequence of continuous transformation in the condensate of two atoms into a molecule and vice versa. For the study of collapse an absorptive contact interaction and an imaginary quartic three-body recombination term are included in the GP equation. It is possible to have a collapse of one or both components when one or more of the nonlinear terms in the GP equation are attractive in nature, respectively.