  Single Photon Detectors (SPD) are fundamental to quantum optics and quantum
information. Superconducting Nanowire SPDs (SNSPD) [1] provide high performance
in terms of quantum efficiency (QE), dark count rate (DCR) and timing jitter
[2], but have limited maximum count rate (MCR) when operated as a free-running
mode (FM) detector [3, 4]. However, high count rates are needed for many
applications like quantum computing [5] and communication [6], and laser
ranging [7]. Here we report the first operation of SNSPDs in a gated mode (GM)
that exploits a single photon triggered latching phenomenon to detect photons.
We demonstrate operation of a large active area single element GM-SNSPD at
625MHz, one order of magnitude faster than its FM counterpart. Contrary to
FM-SNSPDs, the MCR in GM can be pushed to GHz range without a compromise on the
active area or QE, while reducing the DCR.
