Squeezed states in harmonic generation of a laser beam

Solomon Getahun

In this article, we have analyzed the squeezing and statistical properties of the light generated by the superposition of second harmonic light and degenerate three level squeezed laser beams. We have found that the mean photon number of the superposed light beams to be the sum of the mean photon number of that of the constituent light beams. However, the photon number variance of the superposed light beams does not happen to be the sum of the photon number variances of the separate light beams. On the other hand, the quadrature variance of the superposed light beams is the sum of the individual light beams. Furthermore, we have observed that the degree of squeezing for the superposed light beams is the average of the segregate light beams and the degree of squeezing is approximately 53.95% below the coherent state level. Even though, we have verified that the superposition of subharmonic and second harmonic light with injected degenerate three-level laser beams he haves squeezing, we do not show continuous variable entanglement. But, the absence of the laser beam in the superposition state give rise entangled photons.

Iu. M. Golubev

Timothy C. Ralph, Andrew G. White

We report the results of a study of the quantum noise properties of a squeezing system involving a three-level laser pumping two similar second-harmonic-generating crystals. We show that squeezing that has been obscured by intensity and phase noise from the pump laser may be retrieved by difference detection of both second-harmonic outputs. Similarly, the squeezed vacuum formed by combining the two outputs on a 50/50 beam splitter will be squeezed at frequencies that are classically noisy in the individual beams.

Shuichiro Inoue

Liang Wu, Yanhong Liu, Ruijie Deng +3 more

A polarization squeezed optical beam can directly interact with the atomic medium, and its measurement is local-oscillator free. Here we have deterministically generated polarization squeezed light at 795 nm. First, a laser at 398 nm is produced from second-harmonic generation with an enhancement cavity. Then a pair of quadrature amplitude squeezed optical fields is prepared with two degenerate optical parameter amplifiers that are pumped by the resulting laser at 398 nm. Finally, the polarization squeezed state of light is generated by combining the above two quadrature amplitude squeezed optical beams on a polarizing beam splitter, and the quantum fluctuations of three Stokes operators simultaneously are reduced 4.0 dB below the quantum noise limit. The polarization squeezing has potential applications in future quantum information networks.

修一郎 井上