  We demonstrate a 16-pixel array of radio-frequency superconducting nanowire
single-photon detectors with an integrated and scalable frequency-division
multiplexing architecture, reducing the required bias and readout lines to a
single microwave feed line. The electrical behavior of the photon-sensitive
nanowires, embedded in a resonant circuit, as well as the optical performance
and timing jitter of the single detectors is discussed. Besides the single
pixel measurements we also demonstrate the operation of the 16-pixel array with
a temporal, spatial and photon-number resolution.
