A thermal bath induced new resonance on the linear and nonlinear spectra of a two-level system

Within the scope of generalized master equation we have shown the effect of bath with finite band width on the linear absorption and on the resonance fluorescence and absorption spectra of a driven two-state system. It is fou nd that depending on the band width and temperature of the bath a reversibl e dynamics may set in even in the case of linear absorption induced by weak field. At higher temperature the bath induces new resonance on the spectra l profiles. (C) 1999 Elsevier Science B.V. All rights reserved.