Photon-number-resolving (PNR) detectors are a key enabling technology in photonic quantum information processing. Here, we demonstrate the PNR capacity of conventional superconducting nanowire single-photon detectors by performing ultra-high-resolution time-tagging of the detector-generated electrical pulses. This method provides a viable approach for PNR with high detection efficiency and a high operational repetition rate. We present the implementation of such a PNR detector in the telecom C-band and its characterization by measuring the photon-number statistics of coherent light with tunable intensity. Additionally, we demonstrate the capabilities of the detection method by measuring photon-number correlations of non-classical states.
Photon-number-resolving (PNR) detectors are a key enabling technology in photonic quantum information processing. Here, we demonstrate the PNR capacity of conventional superconducting nanowire single-photon detectors by performing ultra-high-resolution time-tagging of the detector-generated electrical pulses. This method provides a viable approach for PNR with high detection efficiency and a high operational repetition rate. We present the implementation of such a PNR detector in the telecom C-band and its characterization by measuring the photon-number statistics of coherent light with tunable intensity. Additionally, we demonstrate the capabilities of the detection method by measuring photon-number correlations of non-classical states.
High Resolution Image Download MS PowerPoint Slide Efficiently distinguishing photon numbers is a crucial yet challenging technology for various quantum information and quantum metrology applications. While superconducting transition edge sensors offer good photon-number-resolving (PNR) capabilities, they are hampered by low detection speed, timing jitter, and complex cooling and readout requirements. In this work, we present a significant advancement toward achieving high-fidelity PNR single-photon detectors by combing high efficiency superconducting nanowire single-photon detector and spatial multiplexing technology. The unique twin-layer configuration of superconducting nanowire atop a dielectric mirror ensures the near-unity detection efficiency. The segmented design, where each section is shunted by a resistor, enables spatial multiplexing, establishing a mapping relationship between pulse amplitude and registered photons. The fabricated detector exhibits impressive performance metrics, including a single-photon system detection efficiency (SDE) of ∼98% at a dark count rate of 20 cps and photon-number resolution capability up to 32. Further characterization through detector tomography reveals high fidelities for two-, three-, and four-photon events, approximately 87%, 73%, and 40% respectively. Moreover, the detector operates at a high count rate of 41 MHz at 3 dB-SDE, with a low timing jitter of as low as 40 ps. With its near-unity efficiency, high photon-number resolution, low dark count rate, fast detection speed, and superior timing resolution, we expect significant interest in these detectors, promising substantial benefits for weak light detection and optical quantum information applications.
Photon-number-resolving (PNR) single-photon detectors are an enabling technology in many areas, such as photonic quantum computing, nonclassical light-source characterization, and quantum imaging.Here, we demonstrate high-efficiency PNR detectors using a parallel superconducting nanowire singlephoton-detector (P-SNSPD) architecture that does not suffer from crosstalk between the pixels and that is free of latching.The behavior of the detector is modeled and used to predict the possible outcomes given a certain number of incoming photons.We apply our model to a four-pixel P-SNSPD with a system detection efficiency of 92.5%.We also demonstrate how this detector allows reconstructing the photonnumber statistics of a coherent source of light, which paves the way towards the characterization of the photon statistics of other types of light source using a single detector.
Abstract We experimentally demonstrate high-fidelity detection of 0, 1- and 2-photon states in a commercial superconducting nanowire single photon detector (SNSPD) under 20 MHz pulsed coherent illumination. The arrival of a different number of photons induces distinct temporal dynamics in the disruption of the superconducting state of the detector. Therefore, specific features emerge in the arrival-time histograms, that we show are directly correlated with the photon-number state. We show that, across a broad range of time-averaged light intensities, the probabilities of detecting 1- and 2 + -photon events collapse onto the Poisson distribution of coherent light. We identify the voltage detection threshold as a critical factor for photon number resolving (PNR) capabilities. Even under demanding conditions of high repetition rate illumination, we found that a high trigger level significantly enhances total detection fidelity, achieving 0.920 and 0.845 for 1-photon and for 2-photon events. These results correspond to remarkably low conditional misidentification probabilities, 0.000 02 and 0.0013, describing the classification error among detected 1- and 2-photon events. We identify an inherent 39 ps latency difference between single- and multi-photon detection events. We show that the measured 2-photon conditional misidentification probability corresponds to the one of a multiplexed PNR detector with 730 pixels. We believe that our findings provide a framework for developing high/fidelity spatially multiplexed SNSPD by exploiting the intrinsic PNR capabilities of individual constituting elements.
The ability to resolve photon numbers is crucial in quantum information science and technology, driving the development of detectors with intrinsic photon-number resolving (PNR) capabilities. Although transition edge sensors represent the state-of-the-art in PNR performance, superconducting nanowire single-photon detectors (SNSPDs) offer superior efficiency, speed, noise reduction, and timing precision. Directly inferring photon numbers, however, has only recently become feasible due to advances in readout technology. Despite this, photon-number discrimination remains constrained by the nanowire's electrical properties and readout jitter. In this work, we employ waveguide-integrated SNSPDs and time-resolved measurements to explore how the nanowire kinetic inductance and system jitter affect PNR capabilities. By analyzing the latency time of the photon detection, we can resolve changes in the rising edge of the detection pulse. We find that lower jitter as well as increased kinetic inductance enhances the pulse separation for different photon numbers and improves the PNR capability. Enhancing the kinetic inductance from 165 nH to 872 nH improves PNR quality by 12%, 31% and 23% over the first three photon numbers, though at the cost of reducing the detector's count rate from 165 Mcps to 19 Mcps. Our findings highlight the trade-off between PNR resolution and detector speed.
Photon-number-resolving (PNR) detectors are essential components of photonic quantum technologies, yet thus far, no practical metric exists to certify how many photons they can genuinely resolve in a single measurement. Here we introduce an operational framework for quantifying the capability of a PNR detector to distinguish between different numbers of photons, i.e. its genuine resolution. In turn, we develop a practical and scalable protocol for certifying the genuine resolution of a detector, which is based on coherent state probes. We apply the method to a 28-pixel photon-number-resolving superconducting nanowire single-photon detector (PNR-SNSPD) and certify genuine four-outcome resolution. Our work highlights the critical requirements in terms of detector efficiency towards achieving high genuine resolution. This approach provides an operational benchmark for PNR detectors and fills a crucial gap in the characterization of photonic quantum devices.
We present an experimental realization of a 16 element, temporal-array, photon-number-resolving (PNR) detector, which is a multiplexed single-photon detector that splits an input signal over multiple time bins, and the time bins are detected using two superconducting nanowire single-photon detectors (SNSPD). A theoretical investigation of the PNR capabilities of the detector is performed and it is concluded that, compared to a single-photon detector, our array detector can resolve one order of magnitude higher mean photon numbers, given the same number of input pulses to measure. This claim is experimentally verified and we show that the detector can accurately predict photon numbers between ${10}^{\ensuremath{-}3}$ and 102. Our present detector is incapable of single-shot photon-number measurements with high precision since its effective quantum efficiency is 49. Using SNSPDs with a higher quantum efficiency the PNR performance will improve, but the photon-number resolution will still be limited by the array size.