Physics and application of photon number resolving detectors based on superconducting parallel nanowires

Abstract

Physics and application of PNR detectors based on superconducting parallel nanowires 2 Abstract. The Parallel Nanowire Detector (PND) is a photon number resolving (PNR) detector which uses spatial multiplexing on a subwavelength scale to provide a single electrical output proportional to the photon number. The basic structure of the PND is the parallel connection of several NbN superconducting nanowires (100 nm-wide, few nm-thick), folded in a meander pattern. PNDs were fabricated on 3-4 nm thick NbN films grown on MgO (T S =400°C) substrates by reactive magnetron sputtering in an Ar/N 2 gas mixture. The device performance was characterized in terms of speed and sensitivity. PNDs showed a counting rate of 80 MHz and a pulse duration as low as 660ps full width at half maximum (FWHM). Building the histograms of the photoresponse peak, no multiplication noise buildup is observable. Electrical and optical equivalent models of the device were developed in order to study its working principle, define design guidelines, and develop an algorithm to estimate the photon number statistics of an unknown light. In particular, the modeling provides novel insight of the physical limit to the detection efficiency and to the reset time of these detectors. The PND significantly outperforms existing PNR detectors in terms of simplicity, sensitivity, speed, and multiplication noise.

Current distribution in a parallel configuration superconducting strip-line detector

“…Moreover, as expected, no pulses were observed after the first; in the single strip switch regime, the strip-line does not recover the initial flowing bias current as already simulated in Ref. 9. It is possible to observe clearly in Fig.…”

“…8 This bias current value is less than the threshold current required to induce the cascade switching of multiple strip-lines; 6 the device operates in the "single-strip switch regime." [9][10][11] In this regime, only the strip-line which has been struck switches partially into the normal state; the other parallel strips in the block remain completely superconducting. The current that was flowing in the impacted strip-line, will be diverted into the neighbouring parallel strips of the block, and only 0.01-1% of this current is diverted into the load impedance of the read-out circuit.…”

Nanowire superconducting single-photon detectors on GaAs for integrated quantum photonic applications

“…Superconducting singlephoton detectors ͑SSPDs͒, 5 based on the photon-induced creation of resistive regions ͑hot spots͒ in nanowires biased close to their critical current, have shown detection efficiencies of up to 30% at = 1.3 m, dark counts in the range of few hertz 5 and are extremely fast ͑with count rates approaching the gigahertz range͒. 6,7 SSPDs have so far been fabricated only on sapphire, 5 MgO, 8 and Si 9 substrates, which are not suitable for the integration with single photon sources. The fabrication of SSPDs on GaAs would enable integration with all the circuitry required for photonic quantum information processing, since GaAs readily lends itself to the largescale production of single-photon sources, 10 waveguides, interferometers, and phase modulators.…”

Superconducting Optoelectronic Circuits for Neuromorphic Computing

“…In Fig. 2(a) we show a circuit diagram of the parallel SNSPD array, referred to as a parallel nanowire detector (PND) [47,48]. One example of an integrate-and-fire circuit is accomplished by placing the PND in parallel with an LED.…”

“…To utilize this to extend the integration time to infinity, the geometry of In addition to utilizing flux trapping to extend the integration time, one may design the L/R time constant to achieve desired performance. In the original studies of the PND for number-resolving detection [47,48], each nanowire was in series with a resistor, while the proposal for the SND for number-resolving detection [50] utilized the dual circuit wherein each series nanowire element is in parallel with a resistor. While the series resistors of the PND are of limited utility in this application due to their addition of power consumption in the steady state, the parallel resistors for the SND can be employed with no steady-state power penalty, and the choice of nanowire element inductance and parallel resistance can thereby be used to engineer the desired integration time.…”