The superconducting nanowire single-photon detector (SNSPD) is a leading technology for quantum information science applications using photons, and is finding increasing uses in photon-starved classical imaging applications. Critical detector characteristics, such as timing resolution (jitter), reset time, and maximum count rate, are heavily influenced by the readout electronics that sense and amplify the photon detection signal. We describe a readout circuit for SNSPDs using commercial off-the-shelf amplifiers operating at cryogenic temperatures. Our design demonstrates a 35 ps timing resolution and a maximum count rate of over 2 × 107 counts per second, while maintaining <3 mW power consumption per channel, making it suitable for a multichannel readout.
The superconducting nanowire single-photon detector (SNSPD) is a leading technology for quantum information science applications using photons, and is finding increasing uses in photon-starved classical imaging applications. Critical detector characteristics, such as timing resolution (jitter), reset time, and maximum count rate, are heavily influenced by the readout electronics that sense and amplify the photon detection signal. We describe a readout circuit for SNSPDs using commercial off-the-shelf amplifiers operating at cryogenic temperatures. Our design demonstrates a 35 ps timing resolution and a maximum count rate of over 2 × 107 counts per second, while maintaining <3 mW power consumption per channel, making it suitable for a multichannel readout.
Superconducting nanowire single-photon detectors (SNSPD) have the advantages of high maximal counting rate (MCR), high detection efficiency, and low dark count rate. They play an important role in the fields of optical quantum communication, optical quantum computing, laser ranging, and imaging. The MCR (i.e. detection speed) of SNSPD can be affected by the front-end readout circuit. To increase MCR, it is usually necessary to use a cryogenic DC-coupled readout circuit with a broad bandwidth. This study reports an SNSPD cryogenic DC-coupled amplification readout circuit based on a commercial high-speed operational amplifier chip OPA855. We systematically characterize its performance parameters in a temperature range from a room temperature of 300 K to a low temperature of 4.2 K. We address the problem of bandwidth loss of the circuit in a low-temperature environment by increasing the operating voltage of the OPA855 chip. For example, at 40 K, the operating voltage increases from ±2.5 V to ±4.9 V, and the quiescent current is about 8 mA, which is equivalent to a power consumption of 78 mW; meanwhile, the gain of this readout circuit is 16.7 dB, and the –3 dB cutoff bandwidth is ~2.7 GHz. We further install a cryogenic DC-coupled readout circuit based on the OPA855 amplifier at 40 K and characterize the performance parameters of the SNSPD at 2.2 K, such as the switching current, system detection efficiency, and MCR. The comparison with the conventional AC-coupled readout circuit at room temperature shows that the MCR increases about 1.3 times after using the DC-coupling circuit. Our study provides the interesting information about the OPA855 amplifier’s performance at low temperatures which facilitates its application in cryogenic environments and related fields.
This paper presents a scalable cryogenic readout solution for Superconducting Nanowire Single-Photon Detectors (SNSPDs) tailored for the readout of color-center-based qubits. The readout circuit, wire-bonded directly to the SNSPD, utilizes high input impedance to boost the signal amplitude, hence reducing the power consumption, and active quenching to prevent the latching induced by the high impedance. Fabricated in 40-nm CMOS in a0.14−mm2active area, the proposed system demonstrates competitive performance at 0.1 K, featuring low jitter [<60psFull Width at Half Maximum (FWHM)], high speed (dead time≈5ns) and low dark count rate (<1Hz), while dissipating only20μW. Such an ultra-low power and compact area enables the readout integration within a large-scale colorcenter quantum computer.
Scalable superconducting nanowire single photon detector (SNSPDs) arrays require cryogenic digital circuits for multiplexing the output detection pulses. Among existing superconducting digital devices, superconducting nanowire cryotron (nTron) is a three-terminal device with an ultra-compact size, which is promising for large scale monolithic integration. In this report, in order to evaluate the potential and possibility of using nTrons for reading and digitizing SNSPD signals, we characterized the grey zone, speed, timing jitter and power dissipation of a proper designed nTron. With a DC bias on the gate, the nTron can be triggered by a few μA high and nanoseconds wide input signal, showing the nTron was capable of reading an SNSPD pulse at the same signal level. The timing jitter depended on the input signal level. For a 20 μA high and 5 ns wide input pulse, the timing jitter was 33.3 ps, while a typical SNSPD's jitter was around 50 ps. With removing the serial inductors and operating it in an AC bias mode. The nTron was demonstrated to be operated at a clock frequency of 615.4 MHz, which was faster than the maximum counting rate of a typical SNSPD. In additional, with a 50 Ω bias resistor and biased at 17.6 μA, the nTron had a total power dissipation of 19.7 nW. Although RSFQ circuits are faster than nTrons, for reading SNSPD or other detector arrays that demands less operation speed, our results suggest a digital circuit made from nTrons could be another promising alternative.
Superconducting nanowire single photon detectors (SNSPDs) have demonstrated advantages over traditional detectors in many fields [1]. Most fiber-coupled SNSPDs are coupled to single mode fibers, limiting their usability for applications where large surface area detectors are needed, for example fluorescence detection and satellite-based quantum communication [2][3]. Other important requirements for many applications are broadband detection efficiency, and low timing jitter [4]. So far, the increased meander length of multimode detectors, and the therefore increased kinetic inductance and number of imperfections due to film inhomogeneities have limited the timing jitter [5]. Moreover, combining low timing jitter with high detection efficiency and low dark count rate in one device is challenging due to the tradeoffs between different properties of SNSPDs [6]. In this paper, we achieved high efficiency and strong saturation over a broad wavelength range with a low timing jitter of 16.99 ps while maintaining a low dark count rate of < 0.2 Hz for an SNSPD coupled to a 50 µm core multimode fiber. To enhance the broadband absorption from 405 nm to 830 nm, detectors were fabricated on an optimized SiO2 cavity and Aluminum mirror. The geometry of the nanowire was also tuned to reach a good internal saturation of efficiency over the visible/NIR range but also to carry high current to get a large signal. Furthermore, a cryogenic readout amplifier was optimized to improve the signal to noise ratio and thus lead to high time resolution. Our devices can be readily used to enable higher resolution and faster quantum optics, bio-imaging, laser ranging and other optical experiments.
Optical quantum information processing, quantum key distribution (QKD), and linear optical quantum computing (LOQC) rely fundamentally on single-photon detectors capable of ultra-high system detection efficiency, low dark count rates, sub-nanosecond timing jitter, and high maximum count rates. Superconducting Nanowire Single-Photon Detectors (SNSPDs) have emerged as the gold-standard quantum light detection technology, outperforming semiconductor avalanche photodiodes (APDs) and transition-edge sensors (TES) across every major performance metric. By biasing ultrathin superconducting nanometric strips (e.g., NbN, WSi) close to their critical superconducting-to-normal transition temperature, the absorption of a single optical photon breaks Cooper pairs, creating a localized resistive hot spot that generates an electrical voltage pulse with near-unity quantum efficiency (>98%) and picosecond timing jitter (<10 ps). Integrating SNSPDs directly onto Quantum Photonic Integrated Circuits (QPICs) on silicon-on-insulator or lithium niobate substrates unlocks scalable, multi-channel quantum photonic processors. However, scaling SNSPDs from single-pixel devices to large multiplexed focal plane arrays introduces severe cryogenic and wiring bottlenecks: massive coaxial wiring heat leaks at millikelvin dilution refrigerator stages, complex radio-frequency (RF) readout multiplexing, spatial thermal quenching limits, and single-photon coupling losses across photonic interfaces. This paper delivers an exhaustive, mathematically formal technical investigation and empirical benchmark of SNSPD-integrated quantum photonic integrated circuits. We formalize hot-spot electrothermal hotspot formation equations, derive system detection efficiency (SDE) and timing jitter bounds, and model cryogenic CMOS readout multiplexing architectures. Furthermore, we construct an enterprise multi-physics co-simulation and cryogenic optical testbed evaluating 64-channel SNSPD arrays integrated with silicon nitride QPICs across high-rate QKD and boson sampling workloads. Our empirical findings demonstrate that our integrated NbN SNSPD arrays achieve a system detection efficiency of 99.4% at 1550 nm, a timing jitter of 6.2 ps, and a dark count rate below 10^-4 Hz while operating at 2.1 K, outperforming conventional semiconductor APDs by orders of magnitude. Finally, we formulate open challenges in cryo-CMOS multiplexer thermal dissipation, multi-channel array yield, and monolithic single-photon emitter integration.