Evaluation of statistical noise in measurements based on correlated photons

Optical measurements in quantum communication and quantum radiometry are quite often based on two-photon correlated channels and the coincidence between them. To quantify the noise level in these measurements, the authors focus on the statistics of photon coincidence in a basic experimental setup, accounting for all experimental effects contributing to the noise increment. By the proposed theory the measurement performance is evaluated in terms of noise fluctuations. Particularly, an ultimate limit in noise reduction is established by the optimal estimation model herein presented. (C) 2002 Optical Society of America.