Two-Photon Interference Constructed by Two Hong–Ou–Mandel Effects in One Mach-Zehnder Interferometer

Abstract

We present a two-photon interference experiment in a modified Mach-Zehnder (MZ) interferometer in which two Hong-Ou-Mandel effects occur in tandem and construct superposed two-photon states. The signal photons pass both the arms of the MZ interferometer while the idler photons pass one arm only. Interestingly, the probability of the idler photons emerging from any output port still shows a sine oscillation with the two-photon phase difference and it can be characterized only by the indistinguishability of the two-photon amplitudes. We also observe a two-photon interference pattern with a period being equal to the wavelength of the parametric photons instead of the two-photon photonic de Broglie wavelength due to the presence of two-photon phase difference, in particular, with complementary probabilities of finding the two-photon pairs in two output ports. The abundant observations can facilitate a more comprehensive understanding of the two-photon interference.

Second-order interference of two independent photons with different spectra*

“…[1] In the same year, Ou et al reported a similar interference experiment with blue and green laser light beams. [2] The second-order interference of photons with different spectra were further studied with photons generated by spontaneous parametric down-conversion, [3][4][5][6][7][8][9][10][11] spontaneous Raman process, [12] single-photon sources, [13] laser and singlephoton source, [14] and chirped laser pulses, [15] etc. The above experiments can be categorized into two groups.…”

“…One group is that the two light beams of different spectra are incident to both input ports of a Shih-Alley/Hong-Ou-Mandel (HOM) interferometer. [1][2][3][4][5][6][7][8][9][10][11][12]16,17] The other one is that two light beams are incident to two input ports of an HOM interferometer, respectively. [13][14][15] The first group of experiments [1][2][3][4][5][6][7][8]10,12] can be easily understood in quantum mechanics.…”