A Landauer formulation of photon transport in driven systems

TL;DR

This paper develops a Landauer-like framework for photon transport in driven, non-equilibrium photonic systems, revealing conditions for analogies with electronic transport and phenomena like two-mode squeezing.

Contribution

It introduces a photonic Landauer formula using non-equilibrium Green's functions, extending electronic transport concepts to driven photonic systems with interactions.

Findings

Photon transport can be described by a Landauer-like formula.

Analogies between photonic and electronic transport are identified.

Conditions for two-mode squeezing in driven photonic systems are established.

Abstract

Understanding the behavior of light in non-equilibrium scenarios underpins much of quantum optics and optical physics. While lasers provide a severe example of a non-equilibrium problem, recent interests in the near-equilibrium physics of so-called photon `gases', such as in Bose condensation of light or in attempts to make photonic quantum simulators, suggest one re-examine some near-equilibrium cases. Here we consider how a sinusoidal parametric coupling between two semi-infinite photonic transmission lines leads to the creation and flow of photons between the two lines. Our approach provides a photonic analog to the Landauer transport formula, and using non-equilbrium Green's functions, we can extend it to the case of an interacting region between two photonic `leads' where the sinusoid frequency plays the role of a voltage bias. Crucially, we identify both the mathematical framework and the physical regime in which photonic transport is directly analogous to electronic transport and regimes in which other behavior such as two-mode squeezing can emerge.