Heralding single photons with a photon-number-resolving superconducting nanowire detector

The seminar will be held in WP108 at 3pm and will be followed by coffee & biscuits in the crush area.

Deterministic generation of single photons is essential for many quantum information technologies. In practice, a common approach is to use a heralded single photon source, in which a bulk optical nonlinearity emits a photon pair and the measurement of one of the photons “heralds” the presence of the other. However, there is constraint on the rate of the heralded photons due to a tradeoff in the single-photon pair and multi-photon pair emission rate of the optical nonlinearity. In this talk, I discuss our work on heralding single photons at telecommunication wavelength with an efficient and low noise photon-number-resolving superconducting nanowire detector. We perform a second-order photon correlation g^2 (0) measurement of the signal mode conditioned on the measured photon number of the idler mode for various pump powers and demonstrate an improvement of a heralded single photon source. We develop an analytical model using a phase space formalism that encompasses all multi-photon effects and relevant imperfections, such as loss and multiple Schmidt modes. We then perform a maximum likelihood fit to test the agreement of the model to the data and extract the best-fit mean photon number μ of the pair source for each pump power. Our experiment, built using fiber-coupled and off-the-shelf components, delineates a path to engineering ideal sources of single photons.