Physical Review Letters

Prospects for Bose-Einstein Condensation in Cesium

S. J. J. M. F. Kokkelmans, B. Verhaar, Kurt Gibble

Published Aug 1, 1998• 35 citations

Abstract

We analyze all of the cold-collision data for Cs, consisting of atomic fountain frequency shifts and elastic scattering rates, to determine phase parameters that completely characterize cold collisions between two ground-state cesium atoms. We show that the fast decays of spin-polarized gas samples in two recent attempts to reach Bose-Einstein condensation in cesium are due to potential and Feshbach resonances which enhance the depolarizing atom-atom collisions. We discuss the prospects for realizing Bose-Einstein condensation in ${}^{133}\mathrm{Cs}$ and in ${}^{135}\mathrm{Cs}$.

DOI: 10.1103/physrevlett.81.951

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Physical Review Letters

Prospects for Bose-Einstein Condensation in Cesium

S. J. J. M. F. Kokkelmans, B. Verhaar, Kurt Gibble

Published Aug 1, 1998• 35 citations

Publisher

Abstract

{}^{133}\mathrm{Cs}

and in

{}^{135}\mathrm{Cs}

DOI: 10.1103/physrevlett.81.951

Related papers

Conditions for Bose-Einstein condensation in magnetically trapped atomic cesium

Eite Tiesinga, A. J. Moerdijk, BOUDEWIJN J. VERHAAR +1 more

We study conditions necessary for the observation of Bose-Einstein condensation in a magnetically trapped sample of atomic Cs gas. These conditions are associated with the value of the elastic scattering length, the rate of elastic scattering events, and the lifetime for decay of the density due to both magnetic dipole relaxation in two-body collisions, as well as recombination to ${\mathrm{Cs}}_{2}$ in three-body collisions. We find that, on the basis of these conditions, the prospects for observing Bose-Einstein condensation are favorable for a gas of ground-state Cs atoms in the highest state of the lowest hyperfine manifold. In all calculated elastic and inelastic two-body rates we find a pronounced resonance structure, which can be understood in terms of the interplay between the singlet-triplet interaction and the hyperfine, Zeeman, and magnetic dipole interactions. The experimental observation of these resonances may help to eliminate present uncertainties about interaction potentials.We study conditions necessary for the observation of Bose-Einstein condensation in a magnetically trapped sample of atomic Cs gas. These conditions are associated with the value of the elastic scattering length, the rate of elastic scattering events, and the lifetime for decay of the density due to both magnetic dipole relaxation in two-body collisions, as well as recombination to ${\mathrm{Cs}}_{2}$ in three-body collisions. We find that, on the basis of these conditions, the prospects for observing Bose-Einstein condensation are favorable for a gas of ground-state Cs atoms in the highest state of the lowest hyperfine manifold. In all calculated elastic and inelastic two-body rates we find a pronounced resonance structure, which can be understood in terms of the interplay between the singlet-triplet interaction and the hyperfine, Zeeman, and magnetic dipole interactions. The experimental observation of these resonances may help to eliminate present uncertainties about interaction potentials.

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Johannes Söding, David Guéry-Odelin, Pierre Desbiolles +2 more

We have measured the rate of inelastic collisions in a cloud of doubly polarized ground-state cesium atoms ( ${F\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}m}_{F}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}4$ ) confined in a magnetic trap for temperatures $T$ between 8 and $70\ensuremath{\mu}\mathrm{K}$. We find a two-body rate coefficient varying as ${T}^{\ensuremath{-}0.63}$. At 8 $\ensuremath{\mu}\mathrm{K}$ it reaches $4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12}\phantom{\rule{0ex}{0ex}}{\mathrm{cm}}^{3}{\mathrm{s}}^{\ensuremath{-}1}$ which is 3 orders of magnitude larger than predicted, ruling out a Bose-Einstein condensation of Cs in this internal state.We have measured the rate of inelastic collisions in a cloud of doubly polarized ground-state cesium atoms ( ${F\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}m}_{F}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}4$) confined in a magnetic trap for temperatures $T$ between 8 and $70\ensuremath{\mu}\mathrm{K}$. We find a two-body rate coefficient varying as ${T}^{\ensuremath{-}0.63}$. At 8 $\ensuremath{\mu}\mathrm{K}$ it reaches $4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12}\phantom{\rule{0ex}{0ex}}{\mathrm{cm}}^{3}{\mathrm{s}}^{\ensuremath{-}1}$ which is 3 orders of magnitude larger than predicted, ruling out a Bose-Einstein condensation of Cs in this internal state.

Physical Review LettersMar 2, 1998105 citations

{}^{133}\mathrm{Cs}

and in

{}^{135}\mathrm{Cs}

{\mathrm{Cs}}_{2}

in three-body collisions. We find that, on the basis of these conditions, the prospects for observing Bose-Einstein condensation are favorable for a gas of ground-state Cs atoms in the highest state of the lowest hyperfine manifold. In all calculated elastic and inelastic two-body rates we find a pronounced resonance structure, which can be understood in terms of the interplay between the singlet-triplet interaction and the hyperfine, Zeeman, and magnetic dipole interactions. The experimental observation of these resonances may help to eliminate present uncertainties about interaction potentials.

Ultracold Cs

_2

Feshbach Spectroscopy

We have observed and located more than 60 magnetic field-induced Feshbach resonances in ultracold collisions of ground-state

^{133}

Cs atoms. These resonances are associated with molecular states with up to four units of rotational angular momentum, and are detected through variations in the elastic, inelastic, and radiative collision cross sections. These observations allow us to greatly improve upon the interaction potentials between two cesium atoms and to reproduce the positions of most resonances to accuracies better than 0.5%. Based on the relevant coupling scheme between the electron spin, nuclear spin, and orbital angular momenta of the nuclei, quantum numbers and energy structure of the molecular states beneath the dissociation continuum are revealed. Finally, we predict the relevant collision properties for cesium Bose-Einstein condensation experiments.

We observe several Feshbach resonances in magnetic fields below 40 G for Cs atoms trapped in a 1D optical lattice. One resonance occurs in the lowest-energy ground state

F\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}3

{m}_{F}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}3

which is stable against inelastic binary collisions. This opens new possibilities for Bose condensation of Cs. When the elastic collision rate far exceeds the radial vibration frequency, we enter a 2D hydrodynamic regime where the thermalization rate is independent of density and temperature. Other resonances are also observed in the

F\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}3

, ${m}_{F}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\ensuremath{-}3$ state through a dramatic increase in the dipolar relaxation rate.

{\mathit{m}}_{\mathit{F}}

=-3 on F=3,

{\mathit{m}}_{\mathit{F}}

=-3 is 1.5(4)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}12}$

{\mathrm{cm}}^{2}

, and is independent of temperature from 30 to 250 \ensuremath{\mu}K. This determination clarifies the technical requirements for attaining Bose-Einstein condensation in a magnetically trapped Cs vapor. We also study heating due to glancing collisions with 300 K background Cs atoms.

We have measured the rate of inelastic collisions in a cloud of doubly polarized ground-state cesium atoms (

{F\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}m}_{F}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}4

) confined in a magnetic trap for temperatures

T

between 8 and $70\ensuremath{\mu}\mathrm{K}$. We find a two-body rate coefficient varying as ${T}^{\ensuremath{-}0.63}$. At 8 $\ensuremath{\mu}\mathrm{K}$ it reaches $4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12}\phantom{\rule{0ex}{0ex}}{\mathrm{cm}}^{3}{\mathrm{s}}^{\ensuremath{-}1}$ which is 3 orders of magnitude larger than predicted, ruling out a Bose-Einstein condensation of Cs in this internal state.