Squeezed states of light upon two-photon generation in noninverted atoms

Nikolay N. Bogolubov, A.S. Shumovsky, Tran Quang

Alexei Ourjoumtsev

János A. Bergou, J. Zhang, C. Su

Both stationary and time-dependent regimes of operation, instabilities, and phase squeezing are investigated in the off-resonant two-photon correlated-spontaneous-emission laser by numerical calculation. Initial atomic coherence plays an essential role in lasing without population inversion, phase locking, and phase noise squeezing in the system. Under certain conditions, in the inverted and noninverted regimes alike, the output intensity exhibits bistable behaviors against the initial atomic coherence. Depending on the parameters, the whole or a portion of the upper or lower branch gives stable operations. In the inverted regime, even tristable behavior can be found in a narrow range of parameters. The field evolution and dynamics are studied. Furthermore, phase noise reduction near bistable areas is also investigated. In addition to the lower branch, where from previous studies, it has been known to exist, phase squeezing is also found on the upper branch both with and without population inversion, thus generating a bright source of phase noise squeezed light.

Alexei Ourjoumtsev, Alexander Kubanek, M. Koch +4 more

В. Н. Горбачев, Andrew I. Trubilko

We propose a theory that makes it possible to examine both laser and micromaser two-photon light generation. The theory is based on the Lamb-Scully model, in which two-level atoms have initial coherence. Such an initial state allows for light generation involving atoms without inversion or even atoms with negative population inversion in the transition. We analyze the conditions needed for the emergence of squeezed states of the light field. We also show that the photon statistics in lasing is always classical but that there appears a state of the field squeezed in the phase with maximum photodetection shot-noise suppression. For a micromaser we find a regime where sub-Poisson light with a shot-noise suppression level of 60% is realized in an inversionless transition. In another regime, a squeezed state that produces 75% suppression of noise can be generated.

Dan Yao, Guang‐Can Guo