Evaporative Cooling of Spin-Polarized Atomic Hydrogen

Masuhara, N.; Doyle, John M.; Sandberg, Jon C.; Kleppner, Daniel; Greytak, Thomas J.; Hess, Harald F.; Kochanski, Greg

doi:10.1103/physrevlett.61.935

Cited by 226 publications

(106 citation statements)

References 7 publications

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“…This process obeys the two-body equation dn/dt = −gn 2 , where n is the local density and g = 1.1 ×10 −15 cm 3 /s is the calculated rate constant [10,18]. When averaged over the density distribution in the trap, this implies that N(t) obeys [16] …”

mentioning

confidence: 99%

“…This increases the wall residence time of H atoms, facilitating recombination, so that contact with the wall effectively removes energetic atoms. This process initiates evaporative cooling [15,16] and thermally disconnects the sample from the wall. The evaporation is forced by decreasing the trap depth, which is set by a saddlepoint in the magnetic field.…”

mentioning

confidence: 99%

“…The temperature [17] and density [16] are measured by rapidly lowering the trap threshold to zero while monitoring the power deposited on a bolometer. The power results from molecular recombination and is proportional to the flux of atoms escaping from the trap.…”

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confidence: 99%

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Cold Collision Frequency Shift of the1S-2STransition in Hydrogen

et al. 1998

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We have observed the cold collision frequency shift of the 1S-2S transition in trapped spin-polarized atomic hydrogen. We find ∆ν 1S−2S = −3.8 ± 0.8 × 10 −10 n Hz cm 3 , where n is the sample density. From this we derive the 1S-2S s-wave triplet scattering length, a 1S−2S = −1.4 ± 0.3 nm, which is in fair agreement with a recent calculation. The shift provides a valuable probe of the distribution of densities in a trapped sample.

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confidence: 99%

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Cold Collision Frequency Shift of the1S-2STransition in Hydrogen

et al. 1998

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“…Magneto-optical traps (MOTs) combine cooling and trapping caused by radiation pressure [17]. Laser-cooling methods combined with magnetic trapping and evaporative cooling methods [18] led to the demonstration of Bose-Einstein condensation in 1995 [19,20].…”

Section: Laser Cooling and Optical Molassesmentioning

confidence: 99%

Ultracold atoms and precise time standards

Campbell

Phillips

2011

Phil. Trans. R. Soc. A.

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Experimental techniques of laser cooling and trapping, along with other cooling techniques, have produced gaseous samples of atoms so cold that they are, for many practical purposes, in the quantum ground state of their centre-of-mass motion. Such low velocities have virtually eliminated effects such as Doppler shifts, relativistic time dilation and observation-time broadening that previously limited the performance of atomic frequency standards. Today, the best laser-cooled, caesium atomic fountain, microwave frequency standards realize the International System of Units (SI) definition of the second to a relative accuracy of ≈3 × 10 −16 . Optical frequency standards, which do not realize the SI second, have even better performance: cold neutral atoms trapped in optical lattices now yield relative systematic uncertainties of ≈1 × 10 −16 , whereas cold-trapped ions have systematic uncertainties of 9 × 10 −18 . We will discuss the current limitations in the performance of neutral atom atomic frequency standards and prospects for the future.

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“…In particular, theories that go beyond the simplest approach based on the Gross-Pitaevskii (GP) equation [4] are under intense study [5][6][7][8]. In this paper, we show how the GP equation can handle the time evolution of Bose condensed gases at finite temperature or in non-equilibrium states.…”

Section: Introductionmentioning

confidence: 99%

Exciting, cooling and vortex trapping in a Bose-condensed gas

Marshall

New²,

Burnett³

et al.

Technical Digest. Summaries of Papers Presented at the Quantum Electronics and Laser Science Conference

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A straight forward numerical technique, based on the Gross-Pitaevskii equation, is used to generate a self-consistent description of thermally-excited states of a dilute boson gas. The process of evaporative cooling is then modelled by following the time evolution of the system using the same equation. It is shown that the subsequent rethermalisation of the thermally-excited state produces a cooler coherent condensate. Other results presented show that trapping vortex states with the ground state may be possible in a two-dimensional experimental environment.

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Evaporative Cooling of Spin-Polarized Atomic Hydrogen

Cited by 226 publications

References 7 publications

Cold Collision Frequency Shift of the1S-2STransition in Hydrogen

Cold Collision Frequency Shift of the1S-2STransition in Hydrogen

Ultracold atoms and precise time standards

Exciting, cooling and vortex trapping in a Bose-condensed gas

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