Photon statistics of a single atom laser

Abstract

We consider a laser model consisting of a single four-level or three-level atom, an optical cavity, and an incoherent pump. Results for photon statistics for varying pump levels are obtained using a quantum trajectory algorithm. In particular, we calculate the mean photon number, Fano factor ͑which is the variance over the mean͒. We examine that the behavior of the single-atom device as ␤, the fraction of spontaneous emission into the lasing mode, is varied. Typical values considered for ␤ are 0.01Ͻ␤Ͻ1.0. We find that for large enough ␤, lasing action, with properties similar to those predicted by semiclassical theories that factorize atom-field correlations and use a small-noise approximation, can occur. Squeezing can occur as ␤ is increased. There is no evidence of a sharp phase transition from weakly excited thermal light to coherent light at a particular pump power. This is consistent with work on many-atom lasers with ␤ values in the range considered here. As ␤ is increased, the output goes from quasithermal light to coherent and finally to squeezed light, progressing into a fully quantum-mechanical regime. We also consider the effects of cavity damping and spontaneous emission rates on these results. ͓S1050-2947͑99͒06510-5͔

Experimental realization of a one-atom laser in the regime of strong coupling

“…B for decreasing l indicates the continuous passage away from the domain of conventional laser operation and into a regime of strong coupling where various nonclassical features emerge (e.g., g (2) (0) < 1), as predicted in prior treatments of one-atom lasers [2,[4][5][6][7][9][10][11][12]. Figure B(d) provides a global perspective of some of these characteristics over a wider range of the pump intensity I 3 for l = l 0 relevant to our experiment.…”

“…Although a number of theoretical treatments related to a one-atom laser have appeared in the literature [2][3][4][5][6][7][8][9][10][11][12], this prior work has not been specific to the parameter range of our experiment as reported in Ref. [1].…”

“…[1], a one-atom laser operated in a regime of strong coupling with (N 0 , n 0 ) 1 will evidence qualitatively different characteristics than those of more familiar conventional lasers. The question then arises as how best to identify a laser in this new regime, with diverse criteria suggested and analyzed in prior work on one-atom lasers [2][3][4][5][6][7][8][9][10][11][12]. The perspective that we adopt here is to trace the lineage of our one-atom laser from a conventional regime continuously into the domain of strong coupling.…”

The Deterministic Generation of Photons by Cavity Quantum Electrodynamics

“…It has been theoretically discussed in many papers [81][82][83][84][85][86][87][88][89][90]. The gain medium is a single atom which couples photons into the resonant mode of the optical cavity.…”

“…The two-level transitions used in the experiments are between 85 Rb Rydberg levels. The rubidium atoms are excited by laser excitation into the 63P 3/2 upper maser level.…”