CHARACTERIZING QUANTUM LIGHT SOURCES VIA THE HANBURY BROWN AND TWISS EFFECT

Abstract

Quantum light sources is an essential element in various applications in quantum optics and quantum information, including quantum information processing, quantum computing, and quantum cryptography. The quality and nature of a light sources are defined by their characteristics which determines their efficiency in quantum applications and processing. In quantum optics, the second-order correlation function, , is a key characteristic of quantum light sources. It is typically measured by the coincidence of signals from two spatially separated detectors in a Hanbury Brown and Twiss (HBT) setup. However, this method is not suitable for bidirectional quantum light sources. In this research, we characterized a bidirectional quantum light source by measuring the conditioned second-order correlation function  from the time delays of two photons in one arm triggered by signals of photons on another arm in a “gated HBT” setup. The light source is generated by the spontaneous parametric down-conversion (SPDC) process in a beta barium borate (BBO) crystal, pumped by a 405-nm continuous-wave laser. This light source, as a result, achieves  = 0.0437, demonstrating the efficiency of our experimental setup for generating a quantum light in an optical laboratory.