Transport in electron-photon systems

TL;DR

This paper reviews the modeling of transport phenomena in electron-photon systems using the nonequilibrium Green's function formalism, covering Coulomb interactions, transverse photons, and full electrodynamics, with applications to heat transfer and emission processes.

Contribution

It provides a comprehensive review of NEGF-based methods for electron-photon transport, including a generalized Meir-Wingreen formula for various electromagnetic interactions.

Findings

Demonstrated heat transfer between graphene sheets driven by potential bias

Analyzed light emission from a double quantum dot system

Studied energy, momentum, and angular momentum emission from graphene nanoribbons

Abstract

We review the description and modeling of transport phenomena among the electron systems coupled via scalar or vector photons. It consists of three parts. The first part is about scalar photons, i.e., Coulomb interactions. The second part is with transverse photons described by vector potentials. The third part is on $\phi=0$ or temporal gauge, which is a full theory of the electrodynamics. We use the nonequilibrium Green's function (NEGF) formalism as a basic tool to study steady-state transport. Although with local equilibrium it is equivalent to the fluctuational electrodynamics (FE), the advantage of NEGF is that it can go beyond FE due to its generality. We have given a few examples in the review, such as transfer of heat between graphene sheets driven by potential bias, emission of light by a double quantum dot, and emission of energy, momentum, and angular momentum from a graphene nanoribbon. All of these calculations are based on a generalization of the Meir-Wingreen formula commonly used in electronic transport in mesoscopic systems, with materials properties represented by photon self-energy, coupled with the Keldysh equation and the solution to the Dyson equation.