Sub-Poissonian laser emission from a single-electron permanently interacting with a single-mode cavity

TL;DR

This paper demonstrates that a semi-classical, stationary laser system involving a single electron can produce sub-Poissonian light with noise below shot noise, challenging the necessity of quantum field quantization for such phenomena.

Contribution

It introduces a semi-classical, exact theory for a single-electron laser system that exhibits sub-Poissonian emission without requiring light quantization.

Findings

Detected noise is 7/8 of shot-noise level

Laser system is strictly stationary and does not need quantized light

Similarities with reflex klystrons are discussed

Abstract

Quiet (or sub-Poissonian) oscillators generate a number of dissipation events whose variance is less than the mean. It was shown in 1984 by Golubev and Sokolov that lasers driven by regular pumps are quiet in that sense. The purpose of this paper is to show that, as long as the laser-detector system is strictly stationary, quantization of the optical field is not required to explain such phenomena. The theory presented here is semi-classical, yet exact. Previous theories considering excited-state atoms regularly-injected in resonators, on the other hand, do require in principle light quantization. Specifically, we consider a laser involving a single electron permanently interacting with the field and driven by a constant-potential battery, and point out a similarity with reflex klystrons. The detected noise is found to be only 7/8 of the shot-noise level. It is therefore sub-Poissonian. Our calculations are related to resonance-fluorescence treatments but with different physical interpretations.