<\/a>Figure 1: a). Schematic of a 2-bit position array by inductive current splitting. The detectors are biased at I<\/em>B<\/sub>. L<\/em>S<\/sub> is the choke inductor. L<\/em>K<\/sub> is the total kinetic inductance of the nanowires, including the active nanowires and the nanowire-inductors. R<\/em>K<\/sub> is the on-chip Ti\/Au resistor. L<\/em>B<\/sub>, C,<\/em> and Z<\/em>0<\/sub> are the inductance of bonding wire, coupling capacitor, and input impedance of the readout circuit, respectively. The orange arrows show the current distribution when the second detector D2 is fired. The width of each arrow is proportional to the amplitude of the current. b). The simulated waveforms of the differential output, V<\/em>L<\/sub>–V<\/em>R<\/sub>. The position information can be clearly read by the amplitude of the pulses. c). The current fluctuation in the unfired detectors when the second detector D2 is fired. All the detectors are biased at 0.8 I<\/em>B<\/sub>\/I<\/em>C<\/sub>. The maximum overshot is 3% of I<\/em>C<\/sub> showing the array can work steadily without being affected much by the fired detector.<\/p><\/div>\nSingle pixels of superconducting nanowire single photon detector (SNSPD) have high detection efficiency, low dark-count rate, and low timing jitter. To achieve a large active area, spatial resolution, or photon-number resolution, an SNSPD array is a promising approach for applications in quantum-information processing, single-photon imaging, and deep-space communication. However, designing a readout scheme is a serious challenge for multi-pixel detector arrays. Two groups have previously used single flux quantum (SFQ) to multiplex the array and have reported some experiment results on single detector [