Photon correlations of multimode laser light

Manabu Yoshikawa, Norihito Suzuki, Tatsuro Suzuki

The photon counting statistics of light transmitted through multimode optical fiber are studied. We have measured the intensity correlation function of light scattered by polystyrene particles suspended in water using transmitted He–Ne laser light. The coherence characteristics are degraded for long fiber and also fluctuations in the intensity occur. The experimental distribution is represented well by the theoretical distribution. The intensity fluctuation is reduced when an incoherent light source is used.

Victor ARTEMYEV

Mateusz Mazelanik, Michał Dąbrowski, Wojciech Wasilewski

We present the possibility of steering the direction of correlations between the off-resonant Raman scattered photons from the angularly multimode atomic memory based on warm rubidium vapors. Using acousto-optic deflectors (AOD) driven by different modulation frequencies, we experimentally change the angle of incidence of the laser beams on the atomic ensemble. By performing correlation measurements for various deflection angles, we verify that we can choose the anti-Stokes light propagation direction independently of the correlated Stokes scattered light in a continuous way. As a result we can select the spatial mode of photons retrieved from the memory, which may be important for future development of quantum information processing.

Yujiang Qu, Surendra Singh

Mario Corti, Vittorio Degiorgio

A. V. Kozlovskiĭ

The mechanism for quantum noise suppression in a multimode laser with a homogeneously broadened line is explained. It is shown that the spontaneous emission noise and pump noise contribution to the photon number fluctuations inside the laser cavity may be suppressed infinitely (up to their complete elimination) when the number of modes participating in the generation is increased. Low-frequency spectral squeezing for an individual output field mode in optimal conditions tends to 100% as the total number of modes increases. The low-frequency spectral squeezing for the total output field may reach 50% below the shot noise level under optimal conditions. The noise suppression of the laser light is explained by the saturation effect of an atomic transition and inter-mode correlation. A multimode laser is an accessible source of light with potentially fully suppressed quantum noise.