Stimulated emission of superradiant atoms in waveguide QED

TL;DR

This paper studies how superradiant atoms in waveguide QED can be stimulated by coherent photon pulses to emit and amplify signals with minimal phase noise, revealing unique quantum amplification properties.

Contribution

It provides an analytical model showing phase-preserving amplification of superradiant emission with reduced phase noise, a novel feature in waveguide QED systems.

Findings

Atoms emit photons coherently into the output pulse.

The amplification preserves phase with minimal noise addition.

Photon-emission probability depends on pulse parameters.

Abstract

We investigate the stimulated emission of superradiant atoms coupled to a waveguide induced by a coherent-state photon pulse. We provide an analytical result when a short $\pi$ pulse is incident, which shows that the atoms emit photons coherently into the output pulse, which remains a coherent state in the short pulse limit. An incident pulse is amplified in phase-preserving manner, where noise is added almost entirely in the phase direction in phase space. This property improves the ratio of intensity signal to noise after the amplification for sufficiently short pulses. This is a unique feature different from general phase-preserving linear amplifiers, where the signal-to-noise ratio deteriorates in the amplification process. We also discuss the dependence of the photon-emission probability on pulse parameters, such as the pulse area and the duration.