We derive the dispersion relation for the propagation of quasiresonant light with frequency ${\mathrm{\ensuremath{\omega}}}_{\mathit{L}}$ in an ultracold gas of bosonic atoms in the dilute regime, i.e., for an atomic density ${\mathrm{\ensuremath{\rho}}}_{0}$\ensuremath{\ll}(${\mathrm{\ensuremath{\omega}}}_{\mathit{L}}$/c${)}^{3}$. In our calculation, valid up to order 2 in density, two types of corrections to the Lorentz-Lorenz formula for the refractive index appear. The first one is due to the bosonic nature of the atoms and its contribution is related to the two-body correlation function. The second correction originates from multiple scattering of photons within pairs of close atoms, giving rise to the resonant van der Waals interaction. The temperature dependence of the refractive index gives a clear signature of quantum statistical effects, even if the degeneracy threshold for Bose-Einstein condensation is not reached.
A calculation of van der Waal's potential of two atoms at large separation has been carried out for hydrogen and helium. The method depends upon a representation of the perturbe...
We have measured the elastic collision cross section for spin polarized atomic cesium. Neutral cesium atoms are optically cooled, then loaded into a dc magnetic trap. We infer t...
We have measured the elastic-scattering cross section of $^{87}\mathrm{Rb}$ atoms in the \ensuremath{\Vert}F=1,${\mathit{m}}_{\mathit{F}}$=-1〉 ground state at 25 \ensuremath{\mu...
Laser cooled sodium atoms are trapped in an optical dipole force trap formed by the intersection of two 1.06 \ensuremath{\mu}m laser beams. Densities as high as $4\ifmmode\times...
We demonstrate the possibility of Bose-Einstein condensation (BEC) of an ideal Bose gas confined by one- and two-dimensional power-law traps. One-dimensional systems display BEC...
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