A high efficiency superconducting nanowire single electron detector

We report the detection of single electrons using a Nb0.7Ti0.3N superconducting wire deposited on an oxidized silicon substrate. While it is known that this device is sensitive to single photons, we show that it also detects single electrons with kilo-electron-volt energy emitted from the cathode of a scanning electron microscope with an efficiency approaching unity. The electron and photon detection efficiency map of the same device are in good agreement. We also observe detection events outside the active area of the device, which we attribute to sensitivity to backscattered electrons.