Showing papers by "Robin Côté published in 2001"
TL;DR: A technique for manipulating quantum information stored in collective states of mesoscopic ensembles by optical excitation into states with strong dipole-dipole interactions that can be employed for controlled generation of collective atomic spin states as well as nonclassical photonic states and for scalable quantum logic gates is described.
Abstract: We describe a technique for manipulating quantum information stored in collective states of mesoscopic ensembles. Quantum processing is accomplished by optical excitation into states with strong dipole-dipole interactions. The resulting "dipole blockade" can be used to inhibit transitions into all but singly excited collective states. This can be employed for a controlled generation of collective atomic spin states as well as nonclassical photonic states and for scalable quantum logic gates. An example involving a cold Rydberg gas is analyzed.
1,310 citations
TL;DR: In this paper, the potential energy curves of the singlet and triplet states of LiH, NaH, KH, RbH, and CsH formed by the approach of ground state alkali-metal atoms and hydrogen atoms are presented.
Abstract: Quantum-mechanical calculations of the potential energy curves of the singlet and triplet states of LiH, NaH, KH, RbH, and CsH formed by the approach of ground state alkali–metal atoms and hydrogen atoms are presented. Precise values are determined for the coefficients of the van der Waals interaction and estimates are made of the contribution of the exchange interaction at large distances. Together with empirical data, they are used to assess and improve the accuracy of the ab initio potentials.
35 citations
TL;DR: In this paper, the authors considered the possibility of enhanced cooling of hydrogen atoms by a buffer gas of alkali-metal atoms Na, K, Rb, and Cs, and showed that the critical conditions for Bose-Einstein condensation of hydrogen could be achieved already at the stage of optical cooling of the sodium or rubidium buffer gas.
Abstract: We consider the possibility of enhanced cooling of hydrogen atoms by a buffer gas of alkali-metal atoms Na, K, Rb, and Cs. Ultracold elastic collision cross sections for the Na-H and Rb-H purely spin-polarized pairs are found to be 640 and 860 times larger than that for the H-H pair, respectively. From an analysis of the techniques of production of ultracold sodium and rubidium samples, it seems feasible that the critical conditions for Bose-Einstein condensation of hydrogen could be achieved already at the stage of optical cooling of the sodium or rubidium buffer gas.
15 citations
TL;DR: In this article, the scattering lengths of 23Na atoms by 39K, 40K and 41K atoms, when they interact via the X 1Σ+ and a 3 Σ+ states of the NaK dimer, are calculated.
Abstract: The scattering lengths that characterize the low-energy elastic scattering of 23Na atoms by 39K, 40K and 41K atoms, when they interact via the X 1Σ+ and a 3Σ+ states of the NaK dimer, are calculated. The systematic variation of the short- and long-range parts of the interaction potentials reveals that the calculated scattering lengths are sensitive to uncertainties in the potentials. It is concluded that precise spectroscopic measurements of the least-bound ro-vibrational levels supported by the ground electronic state, which would reduce the uncertainties in both the molecular potentials, are needed for an accurate determination of the scattering lengths.
9 citations
TL;DR: In this paper, the authors reported calculations of diffusion, excitation transfer, width, and shift cross sections for the impact of collisions of alkali-metal atoms in the impact approximation, and compared these results to analytical expressions obtained from semiclassical treatments, with measured widths for sodium atoms.
Abstract: We report calculations of diffusion, excitation transfer, width, and shift cross sections. We use these cross sections to obtain the diffusion coefficient and the width and line shift due to collisions of alkali-metal atoms in the impact approximation. The results are compared to analytical expressions obtained from semiclassical treatments, and with measured widths for sodium atoms. Extension to other alkali metal atoms is also given.
8 citations
01 May 2001
TL;DR: This work theoretically examine photoassociation of a two-component Fermi degenerate gas and focuses on adjusting the atom-atom interaction, and thereby increasing the critical temperature of the BCS transition to the superfluid state.
Abstract: We theoretically examine photoassociation of a two-component Fermi degenerate gas Our focus is on adjusting the atom-atom interaction, and thereby increasing the critical temperature of the BCS transition to the superfluid state In order to avoid spontaneous decay of the molecules, the photoassociating light must be far-off resonance Very high light intensities are therefore required for effective control of the BCS transition
7 citations
TL;DR: In this article, photoassociation of a two-component Fermi degenerate gas was theoretically examined, and the focus was on adjusting the atom-atom interaction, and thereby increasing the critical temperature of the BCS transition to the superfluid state.
Abstract: We theoretically examine photoassociation of a two-component Fermi degenerate gas Our focus is on adjusting the atom-atom interaction, and thereby increasing the critical temperature of the BCS transition to the superfluid state In order to avoid spontaneous decay of the molecules, the photoassociating light must be far-off resonance Very high light intensities are therefore required for effective control of the BCS transition
7 citations
01 Jan 2001
TL;DR: In this paper, the effects of quasicondensates on the three-body recombination rate in a two-dimensional gas of atomic hydrogen have been observed, and the 1S-2S two-photon absorption lineshapes measured at MIT show distortions that may originate from the formation of metastable quasilicondensate droplets.
Abstract: Over the last few years, the experimental realization of Bose-Einstein condensation (BEC) in dilute alkali-metal atoms [1] and atomic hydrogen [2] has stimulated studies of the formation and evolution of condensates [3]. The kinetics of the condensate formation from a nonequilibrium initial state to a final coherent state has been explored in many systems [4], and particularly in dilute atomic gases [5],[6]. Recently, effects of quasicondensates on the three-body recombination rate in a two-dimensional gas of atomic hydrogen have been observed [7]. The 1S-2S two-photon absorption lineshapes measured at MIT [2],[8] show distortions that may originate from the formation of metastable quasicondensate droplets [9].
1 citations