Non-Markovian Open Quantum Systems: Lorentzian from Markovian
  As a general mission, reduced dynamics and master equations are advocated as alternative method and philosophy instead of Green functions, Kubo theory and the like. A smart reduction of the Lorentzian open system to the Markovian one (Imamoglu, 1994) is presented in simple terms. 
Lajos Di\'osi
quant-ph cond-mat.stat-mech