Linear-Optic Heralded Photon Source
This provides a widely tunable and compatible photon source for fiber-optic quantum communication, though it is incremental as it matches the yield of existing spontaneous parametric down-conversion-based sources.
The researchers tackled the problem of creating a tunable, high-coherence photon source for quantum communication by developing a heralded photon source using only linear optics and weak coherent states, achieving sub-Poisson statistics with a second-order correlation function of 0.556 and 100-nm spectral tunability on telecom bands.
We present a Heralded Photon Source based only on linear optics and weak coherent states. By time-tuning a Hong-Ou-Mandel interferometer fed with frequency-displaced coherent states, the output photons can be synchronously heralded following sub-Poisson statistics, which is indicated by the second-order correlation function ($g^2\left(0\right)=0.556$). The absence of phase-matching restrictions makes the source widely tunable, with 100-nm spectral tunability on the telecom bands. The technique presents yield comparable to state-of-the-art spontaneous parametric down-conversion-based sources, with high coherence and fiber-optic quantum communication compatibility.