Fig. 4. Quantum interference of single photons from a G center in silicon photonics.

a Successive photons (Δτ = 25 ns) interfere via a time-delayed Mach-Zehnder interferometer. Indistinguishability of the interfering single photons is adjusted by setting their relative polarizations using a polarization controller (PC). b Two-photon interference measurement. g⁽²⁾(τ) for orthogonal (blue) and parallel (red) polarizations. (c) When the two photons are indistinguishable, quantum interference results in the antibunching dip at short time delays. We observe nearly identical correlations outside of the quantum interference window. b, c Error bars represent Poissonian noise, and errors in g⁽²⁾(τ) values are extracted from the error of the fits.