Generalized Einstein B coefficients for coherently driven threelevel systems
Abstract
Generalized Einstein B coefficients for coherently driven closed threelevel systems are introduced by means of the quantumjump technique. The nonreciprocity between stimulated emission and absorption for both onephoton and twophoton gain and loss processes has been studied and quantified in terms of the rates of the particular incoherent processes present in each threelevel system. Some general properties of these generalized Einstein B coefficients have been found. In particular, whenever the generalized Einstein B coefficient for onephoton gain overcomes that for onephoton loss then the generalized Einstein B coefficient for twophoton loss overcomes that for twophoton gain, and vice versa. Finally, we have obtained simple analytical expressions indicating the way to maximize the asymmetry between stimulated emission and absorption coefficients either for onephoton or for twophoton processes.
 Publication:

Physical Review A
 Pub Date:
 June 2001
 DOI:
 10.1103/PhysRevA.63.063810
 Bibcode:
 2001PhRvA..63f3810M
 Keywords:

 42.50.Gy;
 32.80.t;
 Effects of atomic coherence on propagation absorption and amplification of light;
 electromagnetically induced transparency and absorption;
 Photon interactions with atoms