Abstract The forces on a single Bose–Einstein condensate confined between two parallel plates consist of two components, namely, surface tension force and Casimir force. In canonical ensemble, these forces are quite different from the one in grand canonical ensemble. In small region with distance
ℓ between two parallel plates, using double parabola approximation, we find that surface tension force decreases as
ℓ−3, whereas the Casimir force, in one-loop approximation of the quantum field, is proportional to
ℓ−13/2. The total force is also considered and its veer is found.
In this paper the interaction between contaminants of the Bose-Einstein condensed system at finite temperature is discussed by using the Thermal Field Dynamics.The system energy and Casimir force between the contaminants are obtained,the relationship of the force with temperature and distance is also discussed.These results will help us further understand the physical effect of contaminants in the Bose-Einstein condensed body and provide certain reference value to Casimir effect and the Bose-Einstein condensation experimental study.
We show how a two dimensional Bose-Einstein Condensate trapped in a nonequilibrium state can be driven into the Rayleigh-Taylor instability if an outward in-plane force is exerted on it. If the condensate is inside a semiconductor, the above force could arise from an inhomogeneous strain applied on the host semiconductor crystal. On the other hand, for a BEC of alkali atoms, the force could be exerted by an inhomogeneous magnetic field turned on after the BEC has been released from its magnetic trap. During its expansion, the condensate will break into droplets each a separate BEC. Therefore, one can create BEC droplets out of a single large BEC and study the coherence properties of the droplets with respect to each other. The discussion on the linear onset of the Rayleigh-Taylor instability in a BEC is generalized to three dimensions.