Coherently excited Hong-Ou-Mandel effects using frequency-path correlation

Nonlocal quantum correlation has been the main issue of quantum mechanics over the last century. The Hong-Ou-Mandel (HOM) effect relates to the two-photon intensity correlation on a beam splitter, resulting in a nonclassical photon-bunching phenomenon. The HOM effect has been used to verify the quantum feature via Bell measurements for quantum technologies such as quantum repeaters and photonics quantum computing. Here, a coherence version of the HOM effect is proposed and analyzed to understand the fundamental physics of the anticorrelation and entanglement. For this, frequency-correlated coherent photon pairs are prepared in an independent set of Mach-Zhender interferometers (MZI) using a synchronized pair of modulators from an attenuated laser. For the HOM effect, the phase relation between frequency-correlated photons plays an essential role. For the product-basis randomness, the symmetrically modulated two independent MZIs are combined together incoherently. A classical intensity product between two independent photodetectors is also discussed for the same HOM effect in a selective macroscopic measurement scheme.