We describe several experimental studies of Bose-Einstein condensation in a dilute gas of sodium atoms. These include studies of static and dynamic behavior of the condensate, and of its coherence properties.

2 Regimes of 1D gases 2 2.1 Strongly versus weakly interacting regimes . . . . . . . . . . . . . . . . . . . . 4 2.2 Nearly ideal gas regime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.3 Quasi-condensate regime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.3.1 Density fluctuations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.3.2 Phase fluc...

In this letter we discuss the relevance of the 3D Perfect Bose gas (PBG) condensation in extremely elongated vessels for the study of anisotropic condensate coherence and the “quasi-condensate”. To this end we analyze the case of exponentially anisotropic (van den Berg) boxes, when there are two critical densities ρc < ρm for a generalised Bose-Einstein Condensation (BEC). Here ρc is the standa...

We find that the key features of the evolution and collapse of a trapped Bose condensate with negative scattering length are predetermined by the particle flux from the non-equilibrium above-condensate cloud to the condensate and by 3-body recombination of Bose-condensed atoms. The collapse, starting once the number of Bose-condensed atoms N 0 reaches the critical value, ceases and turns to exp...

We study the coherent atomic tunneling between two zero-temperature BoseEinstein condensates (BEC) confined in a double-well magnetic trap. Two Gross-Pitaevskii equations for the self-interacting BEC amplitudes, coupled by a transfer matrix element, describe the dynamics in terms of the inter-well phase-difference and population imbalance. In addition to the anharmonic generalization of the fam...