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