A statistical physics approach to light emission by nonequilibirum systems: the generalized Kirchhoff law

In this talk, we discuss several light emission processes which are still not fully understood. While metals do not fluoresce due to the lack of a band gap, metallic nanoparticles pumped by a laser may emit visible light. Several mechanisms have been suggested to explain this effect often called metal photoluminescences [1].  Inelastic tunneling of electrons between two metals across a barrier may emit light. While this phenomenon has been reported in 1976, several observations have remained unexplained [2]. Finally, the observation of photon condensation in pumped semiconductor cavities has remained elusive. In this talk, we introduce a statistical model of light emission which enables to discuss these issues [3]. The starting point is the derivation of a fluctuating relation connecting the nonequilibrium electronic distribution with the current density correlation function. We then show how this approach leads to a generalized form of the Kirchhoff law [4].   

 

1. Loirette-Pelous A. & Greffet J.-J., Theory of Photoluminescences by Metallic Structures, to be submitted

2. Muniain U. et al., Unified treatment of Light Emission by Inelastic Tunneling: Interaction of Electrons and Photons beyond the Gap, Phys. Rev. X 14, 021017 (2024)

3. Loirette-Pelous A. & Greffet J.-J., Photon Bose-Einstein Condensation and Lasing in Semiconductor Cavities, Laser & Photonics Reviews, 2300366 (2023)

4. Greffet J.-J et al., Light Emission by Nonequilibrium Bodies: Local Kirchhoff Law, Phys. Rev. X 8, 021008 (2018)