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Bose–Einstein condensates of dilute atomic gases, characterized by a macroscopic population of the quantum mechanical ground state, are a new, weakly interacting quantum fluid [1, 2, 3]. In most experiments condensates in a single weak field seeking state are magnetically trapped. These condensates can be described by a scalar order parameter similar to the(More)
Bose-Einstein condensates of sodium atoms have been prepared in optical and magnetic traps in which the energy-level spacing in one or two dimensions exceeds the interaction energy between atoms, realizing condensates of lower dimensionality. The crossover into two-dimensional and one-dimensional condensates was observed by a change in aspect ratio and by(More)
We have studied the hydrodynamic flow in a Bose-Einstein condensate stirred by a macroscopic object, a blue-detuned laser beam, using nondestructive in situ phase contrast imaging. A critical velocity for the onset of a pressure gradient has been observed, and shown to be density dependent. The technique has been compared to a calorimetric method used(More)
Coal accounts for about 70% of total electricity generation in India and is likely to remain a key energy source for at least the next 30-40 years. A significant growth in India's coal use is predicted in consonance with the country's continued development. Such an increase must occur through (and, indeed, is dependent upon) environmentally and socially(More)
Atomic matter waves, just like electromagnetic waves, can be focussed, reflected, guided, and split by the passive atom optical elements of today. However, the key for many applications of RF and light waves lies in the availability of amplifiers. These active devices allow small signal detection and have led to the development of masers and lasers. Here we(More)
We have transported gaseous Bose-Einstein condensates over distances up to 44 cm. This was accomplished by trapping the condensate in the focus of an infrared laser and translating the location of the laser focus with controlled acceleration. Condensates of order 10(6) atoms were moved into an auxiliary chamber and loaded into a magnetic trap formed by a(More)
Vortices were imprinted in a Bose-Einstein condensate using topological phases. Sodium condensates held in a Ioffe-Pritchard magnetic trap were transformed from a nonrotating state to one with quantized circulation by adiabatically inverting the magnetic bias field along the trap axis. Using surface wave spectroscopy, the axial angular momentum per particle(More)
Properties of a Bose-Einstein condensate were studied by stimulated, two-photon Bragg scattering. The high momentum and energy resolution of this method allowed a spectroscopic measurement of the mean-field energy and of the intrinsic momentum uncertainty of the condensate. The coherence length of the condensate was shown to be equal to its size. Bragg(More)
Bose-Einstein condensates of sodium atoms have been confined in an optical dipole trap using a single focused infrared laser beam. This eliminates the restrictions of magnetic traps for further studies of atom lasers and Bose-Einstein condensates. More than 5 3 10 6 condensed atoms were transferred into the optical trap. Densities of up to 3 3 10 15 cm 23(More)
Bose-Einstein condensates have been prepared in long-lived metastable excited states. Two complementary types of metastable states were observed. The first is due to the immiscibility of multiple components in the condensate, and the second to local suppression of spin-relaxation collisions. Relaxation via recondensation of noncondensed atoms, spin(More)