Perturbative Fluctuation Dissipation Relation For Nonequilibrium Finite-Frequency Noise In Quantum Circuits

We develop a general perturbative computation of finite-frequency quantum noise that applies, in particular, to both good or weakly transmitting strongly correlated conductors coupled to a generic environment. Under a minimal set of hypotheses, we show that the noise can be expressed through the nonequilibrium dc current only, generalizing a nonequilibrium fluctuation dissipation relation. We use this relation to derive explicit predictions for the nonequilibrium finite-frequency noise for a single channel conductor connected to an arbitrary Ohmic environment.