Measurement of Correlations in the Parametric Down Conversion Field Using Analog Detectors

A method to measure the correlation function of a biphoton field, which does not require single-photon detectors and photocount coincidence schemes, has been proposed and experimentally approved. It is based on the statistical analysis of current data from analog detectors. On an example of the operation of a scheme with analog photomultiplier tubes in the signal and idler channels of degenerate parametric down conversion, it has been shown that this new approach allows one to obtain correlation function values coinciding with the results of the standard photon counting technique. It has been shown how the absolute values of photon numbers and radiation power in the signal channel of the down conversion scheme are determined from the measured correlation function. Analog detection can expand the spectral and dynamic ranges of electromagnetic radiation for the application of quantum optic technologies. A method for the reference-free measurement of the spectral sensitivity of an analog photosensor module has been demonstrated as the first example of application.