Stimulated Emission of Superradiant Atoms in Waveguide Quantum Electrodynamics
Rui Asaoka, Julio Gea-Banacloche, Yuuki Tokunaga, Kazuki Koshino
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 <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>π</a:mi> </a:math> 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 a phase-preserving manner, where noise is added almost entirely in the phase direction in phase space. This property improves the ratio of the 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.