Effect of quantum interference on a three-level atom driven by two laser fields

Akram, U., Ficek, Z. and Swain, S. (2001) Effect of quantum interference on a three-level atom driven by two laser fields. Journal of Modern Optics, 48 6: 1059-1084. doi:10.1080/09500340010020222


Author Akram, U.
Ficek, Z.
Swain, S.
Title Effect of quantum interference on a three-level atom driven by two laser fields
Journal name Journal of Modern Optics   Check publisher's open access policy
ISSN 0950-0349
Publication date 2001-01-01
Sub-type Article (original research)
DOI 10.1080/09500340010020222
Volume 48
Issue 6
Start page 1059
End page 1084
Total pages 26
Editor P.L. Knight
R.W. Boyd
Place of publication United Kingdom
Publisher Taylor & Francis Ltd
Language eng
Subject C1
240301 Atomic and Molecular Physics
780102 Physical sciences
Abstract We study the effect of quantum interference on the population distribution and absorptive properties of a V-type three-level atom driven by two lasers of unequal intensities and different angular frequencies. Three coupling configurations of the lasers to the atom are analysed: (a) both lasers coupled to the same atomic transition, (b) each laser coupled to different atomic transition and (c) each laser coupled to both atomic transitions. Dressed stales for the three coupling configurations are identified, and the population distribution and absorptive properties of the weaker field are interpreted in terms of transition dipole moments and transition frequencies among these dressed states. In particular, we find that in the first two cases there is no population inversion between the bare atomic states, but the population can be trapped in a superposition of the dressed states induced by quantum interference and the stronger held. We show that the trapping of the population, which results from the cancellation of transition dipole moments, does not prevent the weaker field to be coupled to the cancelled (dark) transitions. As a result, the weaker field can be strongly amplified on transparent transitions. In the case of each laser coupled to both atomic transitions the population can be trapped in a linear superposition of the excited bare atomic states leaving the ground state unpopulated in the steady state. Moreover, we find that the absorption rate of the weaker field depends on the detuning of the strong field from the atomic resonances and the splitting between the atomic excited states. When the strong held is resonant to one of the atomic transitions a quasi-trapping effect appears in one of the dressed states. In the quasi-trapping situation all the transition dipole moments are different from zero, which allows the weaker field to be amplified on the inverted transitions. When the strong field is tuned halfway between the atomic excited states, the population is completely trapped in one of the dressed states and no amplification is found for the weaker field.
Keyword Optics
Electromagnetically Induced Transparency
Spontaneous-emission Cancellation
Population-inversion
Dressed States
Resonance Fluorescence
Broadened Resonances
Lambda-system
Absorption
Coherence
Refraction
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Physical Sciences Publications
 
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Created: Wed, 15 Aug 2007, 02:01:29 EST