arXiv:cond-mat/0602069 · Physical Review A

Evaporation of an atomic beam on a material surface

Gael Reinaudi, Thierry Lahaye, A. Couvert, Zhongde Wang, David Guéry-Odelin

Published Mar 14, 2006• 12 citations

Abstract

We report on the implementation of evaporative cooling of a magnetically guided beam by adsorption on a ceramic surface. We use a transverse magnetic field to shift locally the beam towards the surface, where atoms are selectively evaporated. With a $5\text{\ensuremath{-}}\mathrm{mm}$-long ceramic piece, we gain a factor of $1.5\ifmmode\pm\else\textpm\fi{}0.2$ on the phase-space density. Our results are consistent with a 100% efficiency of this evaporation process. The flexible implementation that we have demonstrated, combined with the very local action of the evaporation zone, makes this method particularly suited for the evaporative cooling of a beam.

DOI: 10.1103/physreva.73.035402

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arXiv:cond-mat/0602069 · Physical Review A

Evaporation of an atomic beam on a material surface

Gael Reinaudi, Thierry Lahaye, A. Couvert, Zhongde Wang, David Guéry-Odelin

Published Mar 14, 2006• 12 citations

arXiv HTML PDF

Abstract

5\text{\ensuremath{-}}\mathrm{mm}

-long ceramic piece, we gain a factor of

1.5\ifmmode\pm\else\textpm\fi{}0.2

on the phase-space density. Our results are consistent with a 100% efficiency of this evaporation process. The flexible implementation that we have demonstrated, combined with the very local action of the evaporation zone, makes this method particularly suited for the evaporative cooling of a beam.

DOI: 10.1103/physreva.73.035402

Related papers

Evaporative cooling of a guided rubidium atomic beam

Thierry Lahaye, Zhongde Wang, Gael Reinaudi +3 more

We report on our recent progress in the manipulation and cooling of a magnetically guided, high-flux beam of $^{87}\mathrm{Rb}$ atoms. Typically, $7\ifmmode\times\else\texttimes\fi{}{10}^{9}\phantom{\rule{0.3em}{0ex}}\text{atoms}\phantom{\rule{0.3em}{0ex}}\text{per}\phantom{\rule{0.3em}{0ex}}\text{second}$ propagate in a magnetic guide providing a transverse gradient of $800\phantom{\rule{0.3em}{0ex}}\mathrm{G}∕\mathrm{cm}$ , with a temperature $\ensuremath{\sim}550\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{K}$, at an initial velocity of $90\phantom{\rule{0.3em}{0ex}}\mathrm{cm}∕\mathrm{s}$ . The atoms are subsequently slowed down to $\ensuremath{\sim}60\phantom{\rule{0.3em}{0ex}}\mathrm{cm}∕\mathrm{s}$ using an upward slope. The relatively high collision rate $(5\phantom{\rule{0.3em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1})$ allows us to start forced evaporative cooling of the beam, leading to a reduction of the beam temperature by a factor of 4, and a tenfold increase of the on-axis phase-space density.We report on our recent progress in the manipulation and cooling of a magnetically guided, high-flux beam of $^{87}\mathrm{Rb}$ atoms. Typically, $7\ifmmode\times\else\texttimes\fi{}{10}^{9}\phantom{\rule{0.3em}{0ex}}\text{atoms}\phantom{\rule{0.3em}{0ex}}\text{per}\phantom{\rule{0.3em}{0ex}}\text{second}$ propagate in a magnetic guide providing a transverse gradient of $800\phantom{\rule{0.3em}{0ex}}\mathrm{G}∕\mathrm{cm}$, with a temperature $\ensuremath{\sim}550\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{K}$, at an initial velocity of $90\phantom{\rule{0.3em}{0ex}}\mathrm{cm}∕\mathrm{s}$. The atoms are subsequently slowed down to $\ensuremath{\sim}60\phantom{\rule{0.3em}{0ex}}\mathrm{cm}∕\mathrm{s}$ using an upward slope. The relatively high collision rate $(5\phantom{\rule{0.3em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1})$ allows us to start forced evaporative cooling of the beam, leading to a reduction of the beam temperature by a factor of 4, and a tenfold increase of the on-axis phase-space density.

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Summary form only given. Optical dipole traps facilitate storage of atoms independent of their magnetic sub-state. Trapping at high densities is thus not limited by two-body collisions changing the spin state of the atom, which in the particular case of cesium have so far prevented the attainment of Bose-Einstein condensation in magnetic traps. For evaporative cooling of Cs we use the gravito-optical surface trap (GOST) which consists of a horizontal evanescent-wave (EW) atom mirror in combination with a blue-detuned hollow beam (HE) for transverse confinement. Starting conditions for evaporative cooling are prepared by optical cooling, based on inelastic reflections from the EW.Summary form only given. Optical dipole traps facilitate storage of atoms independent of their magnetic sub-state. Trapping at high densities is thus not limited by two-body collisions changing the spin state of the atom, which in the particular case of cesium have so far prevented the attainment of Bose-Einstein condensation in magnetic traps. For evaporative cooling of Cs we use the gravito-optical surface trap (GOST) which consists of a horizontal evanescent-wave (EW) atom mirror in combination with a blue-detuned hollow beam (HE) for transverse confinement. Starting conditions for evaporative cooling are prepared by optical cooling, based on inelastic reflections from the EW.

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We present a way of evaporative cooling using microwave-induced transitions in a crossed-beam optical dipole trap. By combining the optical and magnetic forces with gravity it allows to spatially select the most energetic atoms and drive them out of the trap by microwave. After 480 ms of evaporation, our data show the phase space density of the Cs atoms increases by a factor of 3.2 and the temperature is reduced from 2.4 µK to 400 nK. The cooling efficiency is mainly limited by the trap heating. This method provides another way to cool neutral atoms in optical trap and reach temperatures in the nano-Kevin regime.We present a way of evaporative cooling using microwave-induced transitions in a crossed-beam optical dipole trap. By combining the optical and magnetic forces with gravity it allows to spatially select the most energetic atoms and drive them out of the trap by microwave. After 480 ms of evaporation, our data show the phase space density of the Cs atoms increases by a factor of 3.2 and the temperature is reduced from 2.4 µK to 400 nK. The cooling efficiency is mainly limited by the trap heating. This method provides another way to cool neutral atoms in optical trap and reach temperatures in the nano-Kevin regime.

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Thierry Lahaye, J. M. M. J. Vogels, Kenneth Günter +3 more

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We demonstrate experimentally the evaporative cooling of a few hundred rubidium-87 atoms in a single-beam microscopic dipole trap. Starting with 800 atoms at a temperature of 125 $\ensuremath{\mu}$K, we produce an unpolarized sample of 40 atoms at 110 nK, within 3 s. The phase-space density at the end of the evaporation reaches unity, close to quantum degeneracy. The gain in phase-space density after evaporation is ${10}^{3}$ . We find that the scaling laws used for much larger numbers of atoms are still valid despite the small number of atoms involved in the evaporative cooling process. We also compare our results to a simple kinetic model describing the evaporation process and find good agreement with the data.We demonstrate experimentally the evaporative cooling of a few hundred rubidium-87 atoms in a single-beam microscopic dipole trap. Starting with 800 atoms at a temperature of 125 $\ensuremath{\mu}$K, we produce an unpolarized sample of 40 atoms at 110 nK, within 3 s. The phase-space density at the end of the evaporation reaches unity, close to quantum degeneracy. The gain in phase-space density after evaporation is ${10}^{3}$. We find that the scaling laws used for much larger numbers of atoms are still valid despite the small number of atoms involved in the evaporative cooling process. We also compare our results to a simple kinetic model describing the evaporation process and find good agreement with the data.

arXiv:1305.3802Physical Review AAug 30, 201340 citations

5\text{\ensuremath{-}}\mathrm{mm}

-long ceramic piece, we gain a factor of

1.5\ifmmode\pm\else\textpm\fi{}0.2

We report on our recent progress in the manipulation and cooling of a magnetically guided, high-flux beam of

^{87}\mathrm{Rb}

atoms. Typically, $7\ifmmode\times\else\texttimes\fi{}{10}^{9}\phantom{\rule{0.3em}{0ex}}\text{atoms}\phantom{\rule{0.3em}{0ex}}\text{per}\phantom{\rule{0.3em}{0ex}}\text{second}$ propagate in a magnetic guide providing a transverse gradient of

800\phantom{\rule{0.3em}{0ex}}\mathrm{G}∕\mathrm{cm}

, with a temperature $\ensuremath{\sim}550\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{K}$, at an initial velocity of

90\phantom{\rule{0.3em}{0ex}}\mathrm{cm}∕\mathrm{s}

. The atoms are subsequently slowed down to $\ensuremath{\sim}60\phantom{\rule{0.3em}{0ex}}\mathrm{cm}∕\mathrm{s}$ using an upward slope. The relatively high collision rate $(5\phantom{\rule{0.3em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1})$ allows us to start forced evaporative cooling of the beam, leading to a reduction of the beam temperature by a factor of 4, and a tenfold increase of the on-axis phase-space density.

1\text{ }\mathrm{m}/\mathrm{s}

. The rate of elastic collisions within the beam is sufficient to ensure thermalization. We show that the evaporation induced by a radio-frequency wave leads to appreciable cooling and an increase in the phase space density. We discuss the perspectives to reach the quantum degenerate regime using evaporative cooling.

{10}^{3}

. We find that the scaling laws used for much larger numbers of atoms are still valid despite the small number of atoms involved in the evaporative cooling process. We also compare our results to a simple kinetic model describing the evaporation process and find good agreement with the data.