Interferometric detection of a single vortex in a dilute Bose-Einstein condensate

Using two radio frequency pulses separated in time we perform an amplitude division interference experiment on a rubidium Bose-Einstein condensate. The presence of a quantized vortex, which is nucleated by stirring the condensate with a laser beam, is revealed by a dislocation in the fringe pattern.Comment: 4 pages, 4 figure

Critical rotation of a harmonically trapped Bose gas

We study experimentally and theoretically a cold trapped Bose gas under critical rotation, i.e. with a rotation frequency close to the frequency of the radial confinement. We identify two regimes: the regime of explosion where the cloud expands to infinity in one direction, and the regime where the condensate spirals out of the trap as a rigid body. The former is realized for a dilute cloud, and the latter for a Bose-Einstein condensate with the interparticle interaction exceeding a critical value. This constitutes a novel system in which repulsive interactions help in maintaining particles together.Comment: 4 pages, 4 figures, submitted to PR

The transverse breathing mode of an elongated Bose-Einstein condensate

We study experimentally the transverse monopole mode of an elongated rubidium condensate. Due to the scaling invariance of the non-linear Schr\"odinger (Gross-Pitaevski) equation, the oscillation is monochromatic and sinusoidal at short times, even under strong excitation. For ultra-low temperatures, the quality factor $Q=\omega_0/\gamma_0$ can exceed 2000, where $\omega_0$ and $\gamma_0$ are the mode angular frequency and damping rate. This value is much larger than any previously reported for other eigenmodes of a condensate. We also present the temperature variation of $\omega_0$ and $\gamma_0$.Comment: 4 pages, 4 figures, submitted to PR

Vortex nucleation through edge states in finite Bose-Einstein condensates

We study the vortex nucleation in a finite Bose-Einstein condensate. Using a set of non-local and chiral boundary conditions to solve the Schr$\ddot{o}$dinger equation of non-interacting bosons in a rotating trap, we obtain a quantitative expression for the characteristic angular velocity for vortex nucleation in a condensate which is found to be 35% of the transverse harmonic trapping frequency.Comment: 24 pages, 8 figures. Both figures and the text have been revise

Stationary states of a rotating Bose-Einstein condensate: routes to vortex nucleation

Consiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7 Rome / CNR - Consiglio Nazionale delle RichercheSIGLEITItal