Quantum Fluctuations in Electrical Multiport Linear Systems

TL;DR

This paper extends classical and quantum fluctuation theorems to multiport electrical systems, including reciprocal and nonreciprocal, and analyzes lossy systems through continuous resistive components.

Contribution

It introduces a quantum extension of the Nyquist-Thevenin theorem for multiport networks and generalizes the fluctuation-dissipation theorem to complex multiport systems.

Findings

Extended Nyquist-Thevenin theorem to quantum multiport systems

Generalized fluctuation-dissipation theorem for multiport networks

Analyzed lossy systems via continuous resistive components

Abstract

We present an extension of the classical Nyquist-Thevenin theorem for multiport classical electrical networks by Twiss to the quantum case. Conversely, we extend the quantum fluctuation-dissipation result for one port electrical systems to the multiport case, both reciprocal and nonreciprocal. Our results are extended to lossy systems by depicting resistive components as continuous limits of purely lossless lumped-element networks. Simple circuit examples are analyzed, including a linear system lacking a direct impedance representation.