Green-Kubo relation for thermal radiation in non-reciprocal systems

We rederive the Green-Kubo relation establishing a connection between the near- and far-field heat transfer between two objects out of equilibrium to the equilibrium fluctuations of these objects in an arbitrary environment. Employing the scattering approach in combination with the fluctuation-dissipation theorem, we generalize the previously derived Green-Kubo expression to the case of non-reciprocal objects and non-reciprocal environments. Copyright (C) EPLA, 2019