Abstract

The talk concerns macroscopic quantum phenomena in dilute trapped Hose-condensed gases. This subject attracts now a great deal of interest, especially in view of recent successful experiments on Hose-Einstein condensation (BEC) in rubidium, lithium and sodium vapors. These experiments open a unique possibility to investigate dynamic properties of a Hose-condensed phase, such as the response of the system to time-dependent variations of the confining field. I will focus attention on this problem, although at present there are more questions here than answers. I will show that the condensate evolves in a completely different way compared to above-condensate particles and discuss the physics behind this evolution process. If initially almost all trapped atoms are in the condensate (T = 0). a fast change of the potential from the initial to final shape brings the system to an excited superpositional state, where the admixture of the (final) ground state can be small. Then, even assuming complete isolation of the system from the environment, there is still the question of how the correlation properties change. Another question concerns trapped gases with negative scattering length, in which the trapping field stabilizes the condensate provided the spacing between adjacent trap levels exceeds the interparticle interaction. Will this hold in the excited superpositional state or will the system “collapse”?.

© 1996 IEEE