Superconducting Single Photon Detectors

This thesis is about the development of a detector for single photons, particles of light. New techniques are being developed that require high performance single photon detection, such as quantum cryptography, single molecule detection, optical radar, ballistic imaging, circuit testing and fluorescence spectroscopy. Superconducting single photon detectors (SSPDs) are sensitive to single photons from the ultraviolet to the near infrared. In this thesis steps has been taken towards improving this type of detectors and implementing them in experiments. We have fabricated SSPDs in the Van Leeuwenhoek Laboratory at the TU Delft from NbTiN on an oxidized silicon substrate and we show world record system detection efficiencies at telecommunication wavelengths. In addtition, we have adjusted the geometry to get rid of the polarization dependence of the quantum efficiency. SSPDs fabricated from a new material show enhanced efficiency at longer wavelengths. Different read out schemes can scale a single pixel to an array of detectors. We have proven by implementing the SSPDs in a Hanbury-Brown Twiss setup that nanowire quantum dots emit single photons. We also have demonstrated that SSPDs are sensitive to single surface plasmon polaritons and single electrons