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Trapping and cooling rubidium in far...

Miller, Kurt Warren.

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Trapping and cooling rubidium in far-off-resonant optical dipole traps.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Trapping and cooling rubidium in far-off-resonant optical dipole traps./
Author:	Miller, Kurt Warren.
Description:	248 p.
Notes:	Source: Dissertation Abstracts International, Volume: 65-06, Section: B, page: 2973.
Contained By:	Dissertation Abstracts International65-06B.
Subject:	Physics, Atomic. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3136639
ISBN:	0496838367

Trapping and cooling rubidium in far-off-resonant optical dipole traps.
Miller, Kurt Warren.

Trapping and cooling rubidium in far-off-resonant optical dipole traps. - 248 p.

Source: Dissertation Abstracts International, Volume: 65-06, Section: B, page: 2973.

Thesis (Ph.D.)--University of Colorado at Boulder, 2004.

This thesis describes the preparation of dense, ultracold samples of tightly confined, optically trapped Rubidium gas. Such samples are useful for a variety of precision measurements where magnetic fields are undesirable or the atomic states of interest cannot be trapped magnetically.

ISBN: 0496838367Subjects--Topical Terms:

1029235
Physics, Atomic.

Trapping and cooling rubidium in far-off-resonant optical dipole traps.
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035 $a (UnM)AAI3136639
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100 1 $a Miller, Kurt Warren. $3 1928712
245 1 0 $a Trapping and cooling rubidium in far-off-resonant optical dipole traps.
300 $a 248 p.
500 $a Source: Dissertation Abstracts International, Volume: 65-06, Section: B, page: 2973.
500 $a Director: Carl E. Wieman.
502 $a Thesis (Ph.D.)--University of Colorado at Boulder, 2004.
520 $a This thesis describes the preparation of dense, ultracold samples of tightly confined, optically trapped Rubidium gas. Such samples are useful for a variety of precision measurements where magnetic fields are undesirable or the atomic states of interest cannot be trapped magnetically.
520 $a In order to increase the number of atoms in the trapped sample, we studied the physics involved in transferring atoms from a magneto-optical trap (MOT) to an optical dipole trap and found ways to optimize the dynamic balance between loading and loss. The loading rate depends on cooling and the flux of atoms into the trap, while the loss rate is due to excited state collisions induced by the MOT light. We found that this loss is strongly enhanced by a long-range radiative escape process, which we were able to suppress by a factor of 15 by adding a sideband frequency to the trapping laser.
520 $a After the initial loading, the atoms are held in the optical dipole trap for further study. We found that large exponential loss rates are induced at intermediate trap polarizations that are neither perfectly linear nor circular. We attribute this loss to ground-state dipole-force fluctuation heating which occurs as the atoms are optically pumped to different spin states by the elliptical trapping light. In the circularly polarized trap, this optical pumping produces highly spin-polarized samples, and we achieved perfect spin-polarization by adjusting the trap wavelength to allow only a single trapped state. These traps should prove useful for spin sensitive precision measurements such as beta-decay asymmetry.
520 $a Signal to noise in precision measurements can be improved by increasing the phase space density of the sample, achieved by decreasing the ratio of temperature to number. To this end, we implemented rf-induced Sisyphus cooling in the circularly polarized trap. High initial cooling rates of 300mu K/s were achieved with negligible atom loss; however, the final temperature was limited to 17muK, where the small fraction of total thermal energy that is removed per cycle reaches equilibrium with the multiple photon recoils required to complete each cycle.
520 $a To allow further, evaporative cooling, we employed a far-infrared trap. With very low heating rates and high initial densities, far-infrared traps have been used to achieve quantum degeneracy by gradually lowering the trap depth. Unfortunately, this is a very inefficient process resulting in few degenerate atoms. To achieve more efficient cooling, we enabled rf-induced evaporation in one dimension by adding a temporary magnetic gradient across our optical trap. Significant cooling was observed, but we were unable to achieve runaway evaporation with our apparatus. The final chapter of this thesis describes the limitations on our cooling process and suggests several promising modifications for future experiments.
590 $a School code: 0051.
650 4 $a Physics, Atomic. $3 1029235
650 4 $a Physics, Optics. $3 1018756
690 $a 0748
690 $a 0752
710 2 0 $a University of Colorado at Boulder. $3 1019435
773 0 $t Dissertation Abstracts International $g 65-06B.
790 1 0 $a Wieman, Carl E., $e advisor
790 $a 0051
791 $a Ph.D.
792 $a 2004
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3136639