In an optical trap, the ground state of spin-1 Bosons such as 23Na, 39K, and 87Rb can be either a ferromagnetic or a “polar” state, depending on the scattering lengths in different angular momentum channel. The collective modes of these states have very different spin character and spatial distributions. While ordinary vortices are stable in the polar state, only those with unit circulation are...

Signals of CPT and Lorentz violation are possible in the context of spectroscopy using hydrogen and antihydrogen. We apply the StandardModel Extension, a broad framework for Lorentz breaking in physics, to various transitions in the hydrogen and antihydrogen spectra. The results show an unsuppressed effect in the transition between the upper two hyperfine sublevels of the ground state of these ...

We report on simulations involving the blockade effect on a dense ultracold gas. The blockade effect is seen when the interaction energy between two excited Rydberg atoms is large enough to shift the two-excitation state out of resonance. In this paper we investigate a system that exhibits a strong van der Waals blockade, where only one out of thousands of atoms can be excited per blockade volu...

We calculated, within the Gross-Pitaevskii formalism, the critical number of atoms for Bose-Einstein condensates with two-body attractive interactions in cylindrical traps with different frequency ratios. In particular, by using the trap geometries considered by Roberts et al. @Phys. Rev. Lett. 86, 4211 ~2001!#, we show that the theoretical maximum critical numbers are given approximately by Nc...

We demonstrate a way to circumvent the interruption of evaporative cooling observed at high bias field for 87 Rb atoms trapped in the (F = 2, m = +2) ground state. Our scheme uses a 3-frequencies-RF-knife achieved by mixing two RF frequencies. This compensates part of the non linearity of the Zee-man effect, allowing us to achieve BEC where standard 1-frequency-RF-knife evaporation method did n...

We describe the "landscape trap" concept, whereby entire landscapes are shifted into, and then maintained (trapped) in, a highly compromised structural and functional state as the result of multiple temporal and spatial feedbacks between human and natural disturbance regimes. The landscape trap concept builds on ideas like stable alternative states and other relevant concepts, but it substantiv...