Theory of light emission from quantum noise in plasmonic contacts: above-threshold emission from higher-order electron-plasmon scattering

TL;DR

This paper presents a theoretical framework linking quantum noise and light emission in plasmonic contacts, revealing higher-order electron-plasmon interactions as the cause of above-threshold emission observed in experiments.

Contribution

It introduces a nonequilibrium Green function approach to describe light emission, highlighting the role of electron-electron interactions mediated by plasmons in atomic-scale contacts.

Findings

Higher-order electron-plasmon interactions cause above-threshold emission.

Quantum noise relates directly to AC conductance and light emission.

The theory explains experimental observations of above-threshold emission.

Abstract

We develop a theoretical framework for the description of light emission from plasmonic contacts based on the nonequilibrium Green function formalism. Our theory establishes a fundamental link between the finite-frequency quantum noise and AC conductance of the contact and the light emission. Calculating the quantum noise to higher orders in the electron-plasmon interaction, we identify a plasmon-induced electron-electron interaction as the source of experimentally observed above-threshold light emission from biased STM contacts. Our findings provide important insight into the effect of interactions on the light emission from atomic-scale contacts.