Direct observation of phase-sensitive Hong-Ou-Mandel interference
Petr Marek, Petr Zapletal, Radim Filip, Yosuke Hashimoto, T. Toyama, Jun–ichi Yoshikawa, Kenzo Makino, Akira Furusawa · Physical Review A · 2017
The quality of individual photons and their ability to interfere are traditionally tested by measuring the Hong-Ou-Mandel photon bunching effect. However, this phase-insensitive measurement only tests the particle aspect of the quantum interference, leaving out the phase-sensitive aspects relevant for continuous-variable processing. To overcome these limitations we formulate a witness capable of recognizing both the indistinguishability of the single photons and their quality with regard to their continuous-variable utilization. We exploit the conditional nonclassical squeezing and show that it can reveal both the particle and the wave aspects of the quantum interference in a single set of direct measurements. We experimentally test the witness by applying it to a pair of independent single photons retrieved on demand.