Fluctuation-dissipation theorem with applications in the electromagnetic field

Abstract

Not so far from equilibrium, a powerful relation exists between the dissipation of energy (or equivalently entropy production) of a given system out of equilibrium and its fluctuations. Moreover, dissipation is nothing but a measure of how intrinsic randomness and chaos affect the transport properties of a system out of equilibrium. This relation is manifested in the fluctuation-dissipation theorem (FDT), which is derived here, along with its quantum extension and an overview of the theory of linear response. The quantum version permits a way to understand its application to electromagnetic radiation (radiative heat transfer and an attractive force at the nanoscale), and will show how fluctuations of the electromagnetic field persist even at zero temperature