Anomalous dispersion and negative group velocity in a coherence-free cold atomic medium

We have observed the propagation of an approximately 35 ns long light pulse with a negative group velocity through a laser-cooled 85Rb atomic medium. The anomalous dispersion results from linear atom-light interaction, and is unrelated to long-lived ground state coherences often associated with fast...

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Bibliographic Details
Published inarXiv.org
Main Authors Brown, William G A, McLean, Russell, Sidorov, Andrei, Hannaford, Peter, Akulshin, Alexander
Format Paper Journal Article
LanguageEnglish
Published Ithaca Cornell University Library, arXiv.org 20.05.2008
Subjects
Dispersion
Group velocity
Laser cooling
Physics - Atomic Physics
Physics - Optics
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Summary:We have observed the propagation of an approximately 35 ns long light pulse with a negative group velocity through a laser-cooled 85Rb atomic medium. The anomalous dispersion results from linear atom-light interaction, and is unrelated to long-lived ground state coherences often associated with fast light in atomic media. The observed negative group velocity (-c/360) in the Rb magneto-optical trap for a pulse attenuated by less than 50% is in good agreement with the value of dispersion measured independently by an RF heterodyne method. The spectral region of anomalous dispersion is between 15 and 40 MHz, which is an order of magnitude wider than that typically associated with ground-state coherences.
ISSN:2331-8422
DOI:10.48550/arxiv.0805.2993