A single-photon turnstile device

Quantum-mechanical interference between indistinguishable quantum particles profoundly affects their arrival time and counting statistics. Photons from a thermal source tend to arrive together (bunching) and their counting distribution is broader than the classical Poisson limit1. Electrons from a thermal source, on the other hand, tend to arrive separately (anti-bunching) and their counting distribution is narrower than the classical Poisson limit2,3,4. Manipulation of quantum-statistical properties of photons with various non-classical sources is at the heart of quantum optics: features normally characteristic of fermions — such as anti-bunching, sub-poissonian and squeezing (sub-shot-noise) behaviours — have now been demonstrated5. A single-photon turnstile device was proposed6,7,8 to realize an effect similar to conductance quantization. Only one electron can occupy a single state owing to the Pauli exclusion principle and, for an electron waveguide that supports only one propagating transverse mode, this leads to the quantization of electrical conductance: the conductance of each propagating mode is then given by GQ = e2/h (where e is the charge of the electron and h is Planck's constant; ref. 9). Here we report experimental progress towards generation of a similar flow of single photons with a well regulated time interval.