We show that in an atomic Bose gas near a Feshbach resonance a quantum phase transition occurs between a phase with only a molecular Bose-Einstein condensate and a phase with both an atomic and a molecular Bose-Einstein condensate. We show that the transition is characterized by an Ising order parameter. We also determine the phase diagram of the gas as a function of magnetic field and temperat...

We present a method of adiabatically changing the local phase-space density of an ultracold gas using a combination of magnetic and optical forces. Applying this method, we observe phase-space density increases in a gas of sodium atoms by as much as 50-fold. The transition to Bose-Einstein condensation was crossed reversibly, attaining condensate fractions of up to 30%. Measurements of the cond...

A fundamental property of a three-dimensional Bose-Einstein condensate is long-range coherence; however, in systems of lower dimensionality, not only is the long-range coherence destroyed but additional states of matter are predicted to exist. One such state is a "transverse condensate," first predicted by van Druten and Ketterle [Phys. Rev. Lett. 79, 549 (1997)], in which the gas condenses in ...

We have observed the Bose-Einstein condensation of an atomic gas in the (quasi)uniform three-dimensional potential of an optical box trap. Condensation is seen in the bimodal momentum distribution and the anisotropic time-of-flight expansion of the condensate. The critical temperature agrees with the theoretical prediction for a uniform Bose gas. The momentum distribution of a noncondensed quan...

We present a numerical study of a trapped binary Bose-condensed gas by solving the corresponding Hartree-Fock equations. The density profile of the binary Bose gas is solved with a harmonic trapping potential as a function of temperature in two and three dimensions. We find a symmetry breaking in the two dimensional case where the two condensates separate. We also present a phase diagram in the...

We study Bose-Einstein condensates with purely dipolar interactions in oblate traps. We find that the condensate always becomes unstable to collapse when the number of particles is sufficiently large. We analyze the instability, and find that it is the trapped-gas analogue of the "roton-maxon" instability previously reported for a gas that is unconfined in 2D. In addition, we find that under ce...

In this contribution, two approaches are followed to predict the saturated liquid density of liquefied natural gas (LNG) mixtures. In one approach, 12 cubic equations of state (EoSs), comprising the popular Peng-Robinson (PR) and Redlich-Kwong-Soave (RKS), are employed to predict the saturated liquid density of 20 LNG mixtures. In the other approach, these EoS are used in conjunction with a rec...

We produce a Bose-Einstein condensate of 39K atoms. Condensation of this species with a naturally small and negative scattering length is achieved by a combination of sympathetic cooling with 87Rb and direct evaporation, exploiting the magnetic tuning of both inter- and intraspecies interactions at Feshbach resonances. We explore the tunability of the self-interactions by studying the expansion...