Superconducting nanowire single-photon detectors (SNSPDs) are efficient measurement devices used for counting single photons. The field of their applications covers experimental quantum-optical studies, optical quantum computing, quantum communication, and others. After registering a photon by such a detector, the next one cannot be registered during the dead time, and after that this ability is smoothly restored. We have included this feature into the photodetection theory and introduced the corresponding photocounting formula. In the regime of continuous-wave detection, the photocounting statistics nonlinearly depends on the density operator due to a memory effect of previous measurement time windows. The considered examples demonstrate the strong influence of the relaxation process and the memory effect on the resulting photocounting statistics of the SNSPDs.
Superconducting nanowire single-photon detectors (SNSPDs) are efficient measurement devices used for counting single photons. The field of their applications covers experimental quantum-optical studies, optical quantum computing, quantum communication, and others. After registering a photon by such a detector, the next one cannot be registered during the dead time, and after that this ability is smoothly restored. We have included this feature into the photodetection theory and introduced the corresponding photocounting formula. In the regime of continuous-wave detection, the photocounting statistics nonlinearly depends on the density operator due to a memory effect of previous measurement time windows. The considered examples demonstrate the strong influence of the relaxation process and the memory effect on the resulting photocounting statistics of the SNSPDs.
Superconducting nanowire single-photon detectors (SNSPDs) are an attractive technology for applications which benefit from high-count rate photon detection such as quantum communication protocols, photon-starved classical communications, metrology of single-emitters, and photonic quantum computing. However, at high-count rates, a significant portion of photons may be incident during recovery intervals following prior detection events. After detection, the device efficiency recovers over nanoseconds to tens of nanoseconds before reaching a steadystate value. Therefore, for a given SNSPD bias current setpoint, a single efficiency and recovery time specification may not be sufficient to characterize the performance of a device at high count rates. Here we present and experimentally validate a model of the recovery time as a function of bias current for any given system efficiency. These results may be used to improve analysis of measurements performed using SNSPDs operating in the high count rate regime.
Photon detectors connect optical and electrical systems by converting light to electrical signals. Single photon detectors detect single photons which measure ultra-weak light. Traditional semiconductor single-photon detectors suffer from high dark count rates, low infrared detection efficiency, and poor temporal resolution. Superconducting-nanowire single-photon detectors (SNSPDs) overcome these limitations using the hotspot effect. SNSPDs have created a solid foundation for optical technologies and become key in quantum information, LiDARs and Deep-Space Communications. This paper reviews working principles and performance metrics: system detection efficiency, dark count rate, recovery time, and timing jitter. The study summarizes applications in quantum information (quantum key distribution, optical quantum computing), single-photon LiDAR, and deep-space optical communication, replacing most single-photon avalanche diodes (SPADs). Recent experiments show that SNSPD-based systems can achieve meter-scale detection of sea fog, interplanetary laser communication over billions of kilometers, and boson sampling with 20 photons. Ongoing research is expected to improve performance in maximum count rate, system integration, and cryogenic operation, as well as to find applications in emerging fields such as environmental monitoring.
Abstract The superconducting nanowire single‐photon detector (SNSPD) is a quantum‐limit superconducting optical detector based on the Cooper‐pair breaking effect by a single photon, which exhibits a higher detection efficiency, lower dark count rate, higher counting rate, and lower timing jitter when compared with those exhibited by its counterparts. SNSPDs have been extensively applied in quantum information processing, including quantum key distribution and optical quantum computation. In this review, we present the requirements of single‐photon detectors from quantum information, as well as the principle, key metrics, latest performance issues, and other issues associated with SNSPD. The representative applications of SNSPDs with respect to quantum information will also be covered.
Superconducting nanowire single-photon detectors (SNSPDs) are a key building block for photonic quantum technologies, as they provide a means for efficient readout of optical circuits with low timing jitter, dark counts and dead time. In this contribution we give a general overview of the working principle of these devices and look into several engineering aspects. We discuss the influence of the stoichiometry of NbTiN thin-films on detector performance and find that a ratio of 65:35 Nb:Ti results in the highest saturation of SNSPDs fabricated from these films. Furthermore, we study the impact of helium ion irradiation on the efficiency of SNSPDs. We show that with this technique the efficiency of an SNSPD can be improved from below 1% to 42%. Finally, we discuss the impact of embedding the SNSPDs into an optical cavity on the system detection efficiency. By employing a half-cavity under the detector we are able to boost the efficiency from 30% to 50% for a detector with a fill factor of 0.33.
Superconducting nanowire single photon detector (SNSPD) is an optical detector with quantum-limit sensitivity. The detection mechanism is based on the Cooper-pair breaking by the photon energy, which results in a phase transition from superconducting state to non-superconducting state. SNSPDs surpass the semiconducting counterparts with high detection efficiency, low dark count rate, small timing jitter, short dead time, broad spectrum sensitivity as well as free-running etc. SNSPDs with high performance have been applied in various fields, such as, quantum information, laser communication, light detection and ranging. The progress of SNSPD research and development, application as well as commercialization at home and abroad in the past few years was summarized. An outlook of SNSPDs' RD as well as applications was also provided.
In the field of quantum technologies, the superconducting nanowire single photon detector(SNSPD) is nowadays well recognized as a key enabling device. SNSPDs combine high detectionefficiency in the visible and near IR spectral ranges, timing jitter as low as 10 ps, low dark count rate(<100 s−1) and cut-off frequency above 100 MHz. These features make it particularly attractive e.g. forfundamental quantum optics experiments and quantum communications.Plug-and-play SNSPDs with fibered optical access, as shown in Figure 1, are based on a meandernanowire defined by patterning an ultrathin (<10 nm) superconducting film. The device is designedso that absorption of a single photon is enough to brake locally the superconducting order, and toinduce a measurable change of the wire’s resistance. Until recently, such devices displayed two mainlimitations: (1) their efficiency did not exceed ~40% due to the limited optical absorption of the thinfilm; and (2) their response was strongly polarization-sensitive, due to the optical anisotropy of thenanowire. I will present two different approaches which enable to get very high (>90% [1]) andpolarization-insensitive [2,3] detection efficiency. We consider designs based on the integration of thenanowire within an optical microcavity (compatible with the plug-and-play configuration) or on topof an optical waveguide (preferred approach for integration in photonic circuits). I will finally discussnovel application prospects of such detectors, with emphasis on photon-number resolution.