The fluctuation-dissipation relation in a resonantly driven quantum   medium
  We calculate the radiation noise level associated with the spontaneous emission of a coherently driven medium. The significant field-induced modification of relation between the noise power and damping constant in a thermal reservoir is obtained. The nonlinear noise exchange between different atomic frequencies leads to violation of standard relations dictated by the fluctuation-dissipation theorem. 
Maria Erukhimova and Mikhail Tokman
quant-ph physics.optics