Phys. Rev. A 71, 022501 (2005) [5 pages]Constraints on dephasing widths and shifts in three-level quantum systemsReceived 2 September 2004; published 2 February 2005 It is shown that the density matrix equations for a three-level quantum system interacting with external radiation fields can lead to negative populations if arbitrary dephasing rates and shifts are included in these equations. To guarantee non-negative populations, the equations themselves impose certain restrictions on the dephasing widths and shifts. The constraints on the widths are shown to be identical to those that can be derived from a model of Markovian dephasing events, independent of any atom-field interaction. © 2005 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevA.71.022501
DOI:
10.1103/PhysRevA.71.022501
PACS:
32.80.−t, 32.70.Jz
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