8 research outputs found
Approaching Bose-Einstein condensation of metastable neon:Over 10<sup>9</sup> trapped atoms
We present an experimental study of the loading of a magneto-optical trap (MOT) from a brightened and slowed beam of metastable neon atoms. The unprecedented high numbers of 9×10920Ne and 3×109 22Ne metastable atoms are trapped under unconventional trap conditions as compared to metastable helium traps, such as low intensity and small detuning. These cause the MOT to have an extraordinarily large volume on the order of 1cm3 and a typical peak density of 1010 atoms/cm3. A simple Doppler model is discussed which explains why the optimum is found under these conditions. The model includes the seventh beam necessary for the last slowing step before loading
Metastable neon collisions: anisotropy and scattering length
In this paper we investigate the effective scattering length of
spin-polarized Ne*. Due to its anisotropic electrostatic interaction, its
scattering length is determined by five interaction potentials instead of one,
even in the spin-polarized case, a unique property among the Bose condensed
species and candidates. Because the interaction potentials of Ne* are not known
accurately enough to predict the value of the scattering length, we investigate
the behavior of as a function of the five phase integrals corresponding to
the five interaction potentials. We find that the scattering length has five
resonances instead of only one and cannot be described by a simple gas-kinetic
approach or the DIS approximation. However, the probability for finding a
positive or large value of the scattering length is not enhanced compared to
the single potential case. The complex behavior of is studied by comparing
a quantum mechanical five-channel numerical calculation to simpler two-channel
models. We find that the induced dipole-dipole interaction is responsible for
coupling between the different |\Omega> states, resulting in an inhomogeneous
shift of the resonance positions and widths in the quantum mechanical
calculation as compared to the DIS approach. The dependence of the resonance
positions and widths on the input potentials turns out to be rather
straightforward. The existence of two bosonic isotopes of Ne* enables us to
choose the isotope with the most favorable scattering length for efficient
evaporative cooling towards the Bose-Einstein Condensation transition, greatly
enhancing the feasibility to reach this transition.Comment: 13pages, 8 eps figures, analytical model in section V has been
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The strain rate in evolutions of (elliptical) vortices in inviscid two-dimensional flows
Rapidly Rotating Bose-Einstein Condensates in and near the Lowest Landau Level
We create rapidly rotating Bose-Einstein condensates in the lowest Landau
level, by spinning up the condensates to rotation rates of the
centrifugal limit for a harmonically trapped gas, while reducing the number of
atoms. As a consequence, the chemical potential drops below the cyclotron
energy . While in this mean-field quantum Hall regime we still
observe an ordered vortex lattice, its elastic shear strength is strongly
reduced, as evidenced by the observed very low frequency of Tkachenko modes.
Furthermore, the gas approaches the quasi-two-dimensional limit. The associated
cross-over from interacting- to ideal-gas behavior along the rotation axis
results in a shift of the axial breathing mode frequency
Approaching Bose-Einstein condensation of metastable neon: Over 109 trapped atoms
We present an experimental study of the loading of a magneto-optical trap (MOT) from a brightened and slowed beam of metastable neon atoms. The unprecedented high numbers of 9×10920Ne and 3×109 22Ne metastable atoms are trapped under unconventional trap conditions as compared to metastable helium traps, such as low intensity and small detuning. These cause the MOT to have an extraordinarily large volume on the order of 1cm3 and a typical peak density of 1010 atoms/cm3. A simple Doppler model is discussed which explains why the optimum is found under these conditions. The model includes the seventh beam necessary for the last slowing step before loading