Quantum Tomograph for Measurement and Characterization of Quantum States of Biphoton Sources

The development of methods and devices for measuring the quantum states of photon fluxes is a matter of current interest. In this paper, we propose a prototype device for characterizing biphoton light sources using quantum tomography based on spontaneous parametric down-conversion. This prototype device is an experimental implementation of a specialized quantum tomograph designed to measure the quantum polarization states of radiation generated by biphoton sources. In this article, we present the operational principle of the device for characterizing biphoton light sources and describe our specially developed software that enables determination of the statistical characteristics of the measured quantum state, calculation of the tomographic and most probable estimates of the density matrix, and the measurement errors of the density matrix elements, as well as evaluation of the quality of the quantum state of the biphotons.