Niels Bohr Institutet > Kalender - det sker på NBI > 2009 > Thermodynamics of ligh...

Thermodynamics of light amplification and light purification

I will present a full thermodynamical treatment of light-matter interactions in which a three-level system is coupled to a selected cavity mode and two photonic heat reservoirs. The first part of my talk is devoted to a semiclassical treatment in which the field is represented by a time-dependent external field. Based on a general thermodynamical framework for unipartite systems, three thermodynamical pictures exist: heat engine, refrigerator, and squanderer. In the second part of my talk I will present a general thermodynamical framework for bipartite systems developed in my PhD. This is then applied to a full quantum model in which the three-level system is coupled to a quantized cavity mode. Three scenarios are discussed: infinite amplification where the amplifier's efficiency is calculated through thermodynamical fluxes at steady state, saturated amplification, and light attenuation which may lead to light purification. Finally, a comparison of the semiclassical and quantum models is presented.