Spectrum of squeezing for two-photon correlated-spontaneousemission lasers

János A. Bergou, Ning Lü, Marlan O. Scully

Luigi A. Lugiato, Ning Lü, Marlan O. Scully

Ning Lu

Using a two-photon correlated-spontaneous-emission laser (CEL) as an example, I show that a non-Lorentzian spectrum of squeezing is the result of fluctuation coupling and that the narrow peak at the center of the spectrum is a reflection of the fluctuations in the conjugate quadrature. More than 90% extracavity phase squeezing can be generated by the two-photon CEL near threshold with large one-photon detunings.

Aliyyi Adem

Abstract This research aims to study the squeezingand entanglement features of light in three-level atomsunder an open cavity with coherent light excitation.Using an approximation scheme for large timescales,we obtained the steady-state solutions of the evolutionequations for the atomic operators’ expectation valuesand the quantum Langevin equation for the cavity modeoperators. We employed these steady-state solutions todepict the squeezing characteristics, magnification ofentanglement, and normalized second-order correlationof the cavity radiation.The results of our researchshow that the light produced by the three-level lasergets squeezed, mainly in the minus quadrature. Themaximum quadrature squeezing for the light in thetwo-mode cavity is obtained as 37.9% at hni th = 0,and 37.5% at hni th = 0.02, and 37.2% at hni th = 0.03below the vacuum-state level. We demonstrated thatthe average and the variance of the number of photonsdecrease under the influence of spontaneous emission.Moreover, we determined that both the average andthe variance of the photon number are amplified bythe thermal reservoir effect. Additionally, we foundthat quadrature squeezing is enhanced by spontaneousemission, and some entanglement is created. In two-mode light, squeezing and entanglement are directlyrelated, such that an increase in squeezing producesmore entanglement and vice versa.

Ashish Agarwal, Rupamanjari Ghosh

We present the quantum theory of a two-photon nonlinear laser when the lasing medium consists of long-lived atoms. There is no population inversion in this laser, but the system exhibits gain arising from the four-wave-mixing process in an active nonlinear medium. The strong phase correlation between the photons generated in four-wave mixing leads to a narrower than usual linewidth of the two-photon laser far above threshold. The laser output is also squeezed. Systems with a higher lifetime have the advantage of requiring a lower pump to reach the threshold of laser oscillation. We give explicit solutions for the noise spectrum of the intensity difference of the two output modes in the steady state and show that it is highly squeezed even for non-Markov systems.

Julio R. Gea-Banacloche, Ning Lü, Sudhakar Prasad +3 more