Nonadiabatic dynamics in evaporative cooling of trapped atoms by a radio-frequency field
| Autor: | Kalle-Antti Suominen, Eite Tiesinga, Paul Julienne |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
Condensed Matter::Quantum Gases
Physics Field (physics) Spin states Energetic neutral atom Atomic Physics (physics.atom-ph) Relaxation (NMR) Evaporation FOS: Physical sciences Trapping Kinetic energy 01 natural sciences Atomic and Molecular Physics and Optics Physics - Atomic Physics 010305 fluids & plasmas 0103 physical sciences Physics::Atomic Physics Atomic physics 010306 general physics Evaporative cooler |
| Zdroj: | Physical Review A. 58:3983-3992 |
| ISSN: | 1094-1622 1050-2947 |
| DOI: | 10.1103/physreva.58.3983 |
| Popis: | Magnetically trapped neutral atoms can be cooled with the evaporation technique. This is typically done by using a radiofrequency (rf) field that adiabatically couples trapped and untrapped internal atomic states for atoms with kinetic energies above a value set by the field frequency. The rf-field can also induce nonadiabatic changes of internal atomic spin states (F,M) that lead to heating and enhanced loss of atoms. In this paper we use wave packet simulations to show that the evaporation process can induce these nonadiabatic transitions which change the internal spin state of doubly spin-polarized (2,2) trapped atoms. We also verify the validity of a multistate Landau-Zener model in describing the nonadiabatic dynamics. In addition, we calculate exchange relaxation rate coefficients for collisions between atoms in the (2,M) states of 23-Na atoms. Large exchange relaxation coefficients for 23-Na as compared to 87-Rb F=2 suggest that evaporative cooling of (2,2) Na will be more difficult than for the corresponding state of Rb. 13 pages, RevTex, 5 embedded eps figures |
| Databáze: | OpenAIRE |
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