Pure Single Photons From Scalable Frequency Multiplexing

We demonstrate multiphoton interference using a resource-efficient frequency multiplexing scheme,suitable for quantum information applications that demand multiple indistinguishable and pure singlephotons. In our source, frequency-correlated photon pairs are generated over a wide range of frequenciesby pulsed parametric down conversion. Indistinguishable single photons of a predetermined frequencyare prepared using frequency-resolved detection of one photon to control an electro-optic frequency shiftapplied to its partner. Measured photon statistics show multiplexing increases the probability of deliver-ing a single photon, without a corresponding increase to multiphoton events. Interference of consecutiveoutputs is used to bound the modal purity and demonstrate the nonclassical nature of the emitted light