Decoherence and coherent population transfer between two coupled systems

Akram, U, Ficek, Z and Swain, S (2000) Decoherence and coherent population transfer between two coupled systems. Physical Review A, 62 013413: 013413-1-013413-12. doi:10.1103/PhysRevA.62.013413

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Author Akram, U
Ficek, Z
Swain, S
Title Decoherence and coherent population transfer between two coupled systems
Journal name Physical Review A   Check publisher's open access policy
ISSN 1050-2947
Publication date 2000-01-01
Sub-type Article (original research)
DOI 10.1103/PhysRevA.62.013413
Open Access Status File (Publisher version)
Volume 62
Issue 013413
Start page 013413-1
End page 013413-12
Total pages 12
Place of publication College Park, US
Publisher American Physical Soc.
Language eng
Subject 240402 Quantum Optics and Lasers
780102 Physical sciences
Abstract We show that an arbitrary system described by two dipole moments exhibits coherent superpositions of internal states that can be completely decoupled fi om the dissipative interactions (responsible for decoherence) and an external driving laser field. These superpositions, known as dark or trapping states, can he completely stable or can coherently interact with the remaining states. We examine the master equation describing the dissipative evolution of the system and identify conditions for population trapping and also classify processes that can transfer the population to these undriven and nondecaying states. It is shown that coherent transfers are possible only if the two systems are nonidentical, that is the transitions have different frequencies and/or decay rates. in particular, we find that the trapping conditions can involve both coherent and dissipative interactions, and depending on the energy level structure of the system, the population can be trapped in a linear superposition of two or more bare states, a dressed state corresponding to an eigenstate of the system plus external fields or, in some cases. in one of the excited states of the system. A comprehensive analysis is presented of the different processes that are responsible for population trapping, and we illustrate these ideas with three examples of two coupled systems: single V- and Lambda-type three-level atoms and two nonidentical tao-level atoms, which are known to exhibit dark states. We show that the effect of population trapping does not necessarily require decoupling of the antisymmetric superposition from the dissipative interactions. We also find that the vacuum-induced coherent coupling between the systems could be easily observed in Lambda-type atoms. Our analysis of the population trapping in two nonidentical atoms shows that the atoms can be driven into a maximally entangled state which is completely decoupled from the dissipative interaction.
Keyword Optics
Physics, Atomic, Molecular & Chemical
Electromagnetically Induced Transparency
Spontaneous-emission Cancellation
Inhibited Spontaneous Emission
Quantum Interference
Resonance Fluorescence
3-level System
Trapped Atoms
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Physical Sciences Publications
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Citation counts: TR Web of Science Citation Count  Cited 45 times in Thomson Reuters Web of Science Article | Citations
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Created: Mon, 13 Aug 2007, 21:50:44 EST