Radiative decay of densely confined atoms

K. Helmerson, M. Xiao, D. Pritchard

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The extent to which the rate of spontaneous emission may be altered by the mode structure of the atom and by the presence of other ground state atoms in the modes is investigated theoretically. To estimate the amount of suppression or enhancement of the radiative decay rate, atoms confined in a spherically symmetric harmonic potential are considered. For lithium atoms (6Li) cooled to on the order of their recoil energy (2.8 μK) a reasonably degenerate Fermi gas results. Since the trap matrix element favors transitions between trap states that differ in energy by approximately the recoil energy, absorption followed by spontaneous emission will most often place the atom in a state with energy well within two times the recoil energy of the initial stage. Since this quantity is less than Ef, it is expected that most atoms excited from within the Fermi sea will want to decay back within it, leading to suppression of the decay rate by a factor on the order of Ef divided by the recoil energy. There will also be a red shift of the spontaneous emission relative to the excitation light, which may heat the atoms. A densely confined system of Bose atoms (e.g., 7Li) will experience an increase in the spontaneous emission rate of comparable magnitude when kBT ≈ Ef. As the temperature of Bose condensation is approached, the spontaneous emission is shifted to the blue. This represents a new cooling mechanism.

Original languageEnglish
Title of host publicationProceedings
Number of pages1
Publication statusPublished - 1 Dec 1990
Externally publishedYes
Event17th International Conference on Quantum Electronics - IQEC '90 - Anaheim, United States of America
Duration: 21 May 199025 May 1990


Conference17th International Conference on Quantum Electronics - IQEC '90
Country/TerritoryUnited States of America

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