Second-order interference of two independent photons with different spectra**Project supported by the Key Research and Development Project of Shaanxi Province, China (Grant No. 2019ZDLGY09-08), the Open Fund of MOE Key Laboratory of Weak-Light Nonlinear Photonics, China (Grant No. OS19-2), and the Fundamental Research Funds for the Central Universities, China.

Abstract

The second-order interference of two independent photons with different spectra in a Shih–Alley/Hong–Ou–Mandel interferometer is studied in Feynman’s path integral theory. There is a second-order interference pattern for photons with different spectra if the photons are indistinguishable for the employed detection system. The conditions to observe the second-order temporal beating with photons of different spectra are analyzed. The influence of the response time of the detection system on the observed second-order interference pattern is also discussed. It is a direct result of that measurement in quantum mechanics is dependent on the employed measuring apparatus. The results are helpful to understand the physics of two-photon interference in different schemes.