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Improvements in temporal resolution of single-photon detectors enable increased data rates and transmission distances for both classical and quantum optical communication systems, higher spatial resolution in laser ranging, and observation of shorter-lived fluorophores in biomedical imaging. In recent years, superconducting nanowire single-photon detectors (SNSPDs) have emerged as the most efficient time-resolving single-photon-counting detectors available in the near-infrared, but understanding of the fundamental limits of timing resolution in these devices has been limited due to a lack of investigations into the timescales involved in the detection process. We introduce an experimental technique to probe the detection latency in SNSPDs and show that the key to achieving low timing jitter is the use of materials with low latency. By using a specialized niobium nitride SNSPD we demonstrate that the system temporal resolution can be as good as 2.6 ± 0.2 ps for visible wavelengths and 4.3 ± 0.2 ps at 1,550 nm.Knowledge about detection latency provides a guideline to reduce the timing jitter of niobium nitride superconducting nanowire single-photon detectors. A timing jitter of 2.6 ps at visible wavelength and 4.3 ps at 1,550 nm is achieved.

Coincidence detection of single photons is crucial in numerous quantum technologies and usually requires multiple time-resolved single-photon detectors. However, the electronic readout becomes a major challenge when the measurement basis scales to large numbers of spatial modes. Here, we address this problem by introducing a two-terminal coincidence detector that enables scalable readout of an array of detector segments based on superconducting nanowire microstrip transmission line. Exploiting timing logic, we demonstrate a sixteen-element detector that resolves all 136 possible single-photon and two-photon coincidence events. We further explore the pulse shapes of the detector output and resolve up to four-photon events in a four-element device, giving the detector photon-number-resolving capability. This new detector architecture and operating scheme will be particularly useful for multi-photon coincidence detection in large-scale photonic integrated circuits.

Classical and quantum space-to-ground communications necessitate highly sensitive receivers capable of extracting information from modulated photons to extend the communication distance from near-earth orbits to deep space explorations. To achieve gigabit data rates while mitigating strong background noise photons and beam drift in a highly attenuated free-space channel, a comprehensive design of a multi-functional detector is indispensable. In this study, we present an innovative compact multi-pixel superconducting nanowire single-photon detector array that integrates near-unity detection efficiency (91.6%), high photon counting rate (1.61 Gcps), large dynamic range for resolving different photon numbers (1–24), and four-quadrant position sensing function all within one device. Furthermore, we have constructed a communication testbed to validate the advantages offered by such an architecture. Through 8-PPM (pulse position modulation) format communication experiments, we have achieved an impressive maximum data rate of 1.5 Gbps, demonstrating sensitivities surpassing previous benchmarks at respective speeds. By incorporating photon number information into error correction codes, the receiver can tolerate maximum background noise levels equivalent to 0.8 photons/slot at a data rate of 120 Mbps—showcasing a great potential for daylight operation scenarios. Additionally, preliminary beam tracking tests were conducted through open-loop scanning techniques, which revealed clear quantitative dependence indicating sensitivity variations based on beam location. Based on the device characterizations and communication results, we anticipate that this device architecture, along with its corresponding signal processing and coding techniques, will be applicable in future space-to-ground communication tasks.

Efficiently fabricating a cavity that can achieve strong interactions between terahertz waves and matter would allow researchers to exploit the intrinsic properties due to the long wavelength in the terahertz waveband. Here we show a terahertz detector embedded in a Tamm cavity with a record Q value of 1017 and a bandwidth of only 469 MHz for direct detection. The Tamm-cavity detector is formed by embedding a substrate with an Nb 5 N 6 microbolometer detector between an Si/air distributed Bragg reflector (DBR) and a metal reflector. The resonant frequency can be controlled by adjusting the thickness of the substrate layer. The detector and DBR are fabricated separately, and a large pixel-array detector can be realized by a very simple assembly process. This versatile cavity structure can be used as a platform for preparing high-performance terahertz devices and opening up the study of the strong interactions between terahertz waves and matter. Here the authors report a terahertz detector with a Q value of 1017, embedded in a Tamm cavity and offers a 469 MHz bandwidth. It features an Nb5N6 microbolometer in an Si/air DBR and metal reflector, with tunable resonant frequency via substrate layer thickness.

Islet inflammation severely impairs pancreatic β‐cell function, but the specific mechanisms are still unclear. Interleukin1‐β (IL‐1β), an essential inflammatory factor, exerts a vital role in multiple physio‐pathologic processes, including diabetes. Calcium/calmodulin‐dependent serine protein kinase (CASK) is an important regulator especially in insulin secretion process. This study aims to unveil the function of CASK in IL‐1β–induced insulin secretion dysfunction and the possible mechanism thereof. Islets of Sprague‐Dawley (SD) rats and INS‐1 cells stimulated with IL‐1β were utilized as models of chronic inflammation. Insulin secretion function associated with Cask and DNA methyltransferases (DNMT) expression were assessed. The possible mechanisms of IL‐1β‐induced pancreatic β‐cell dysfunction were also explored. In this study, CASK overexpression effectively improved IL‐1β‐induced islet β‐cells dysfunction, increased insulin secretion. DNA methyltransferases and the level of methylation in the promoter region of Cask were elevated after IL‐1β administration. Methyltransferase inhibitor 5‐Aza‐2’‐deoxycytidine (5‐Aza‐dC) and si‐DNMTs partially up‐regulated CASK expression and reversed potassium stimulated insulin secretion (KSIS) and glucose‐stimulated insulin secretion (GSIS) function under IL‐1β treatment in INS‐1 and rat islets. These results reveal a previously unknown effect of IL‐1β on insulin secretion dysfunction and demonstrate a novel pathway for Cask silencing based on activation of DNA methyltransferases via inducible nitric oxide synthase (iNOS) and modification of gene promoter methylation.

The pursuit of green and sustainable energy is a long‐term goal for modern society and people's life. Particularly under the context of carbon neutralization, decarbonization has become a consensus and propels the turning of research enthusiasm to explore new materials and chemistries for energy conversion and storage at a low expenditure. Zinc (Zn) enabled redox flow batteries (RFBs) are competitive candidates to fulfill the requirements of large‐scale energy storage at the power generation side and customer end. Considering the explosive growth, this review summarizes recent advances in material chemistry for zinc‐based RFBs, covering the cathodic redox pairs of metal ions, chalcogens, halogens, and organic molecules. After a brief introduction of common issues for Zn2+/Zn conversion reaction at the anode side, the focus is devoted to expounding challenges of redox species and possible problem‐solving strategies at the cathode side. Besides, the auxiliary components of separator and current collector are also discussed for achieving optimal RFBs' performance. At last, the conclusion and outlook of future endeavor for Zn‐based RFBs implementation are put forward. Zinc enabled redox flow batteries are promising candidates of large‐scale energy storage for green energy to attain the target of carbon neutralization, triggering vast research enthusiasm. Recent advances in material chemistry for this topic are summarized, covering challenges and tactics at zinc anode, cathode, and critical auxiliary components for achieving practical performance. Future endeavors are also put forward.

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.

Integrated quantum photonics (IQP) allows for on-chip generation, manipulation and detection of quantum states of light, fostering advancements in quantum communication, quantum computing, and quantum information technologies. Single-photon detector is a key device in IQP that allows for efficient readout of quantum information through the detection of single-photon statistics and measurement of photonic quantum states. The efficacy of quantum information retrieval hinges on the ability to simultaneously detect every single photon with high efficiency, a relationship that grows exponentially with the number of photons ( n ). Even a slight decrease in single photon detection efficiency can lead to a significant reduction in probability as n grows larger. Here, we introduce a superconductor-semiconductor heterogeneous integration technology that allows for the integration of transversal superconducting nanowires single-photon detectors that eliminate corner loss on various optical waveguides with exceptional efficiency and versatility. Two cascaded nanowires have been integrated on one silicon waveguide, which not only boosts the detection efficiency to 99.73% at a wavelength of 1550 nm but also provides an on-chip calibration setup, allowing such high efficiency to be measured despite the large loss from fiber-to-waveguide coupling and uncertainties from absolute power calibrations. These advancements represent a substantial improvement compared to previous records, approaching the theoretical limit achievable on silicon waveguide, and demonstrate the versatility of heterogeneous integration technology. This breakthrough in ultra-high detection efficiency establishes a new baseline for assessing quantum measurement capabilities on scalable IQP platforms. Superconducting Nanowires on Silicon Waveguide Achieve 99.73% Single-Photon Detection Efficiency, Enabling Precision Quantum Measurement on Scalable Integrated Platforms.

Scaling superconducting nanowire single-photon detectors into a large array to obtain imaging capability is desired for applications in photon-starved conditions, considering the outstanding performance already demonstrated on a single detector. However, this is challenging because the ultralow operation temperature only allows specific electronics of ultralow power dissipation to work. Here we develop a kilopixel imager by introducing an orthogonal time–amplitude-multiplexing method. This readout is solely built in the superconducting nanowire by geometrically designing the nanowire structure to manipulate its hotspot growth and microwave propagation after photon detection. As a result, pixel locations are encoded on both time and amplitude domains of the output pulses. This dual multiplexing method overcomes the previous limitation of a time-multiplexing readout, where the time measurement uncertainty deteriorates the spatial resolution and scalability. Experimentally, with two readout lines, we have demonstrated a 32 × 32 imager with an average readout pixel fidelity of 97% and an average temporal resolution of 67.3 ps. The performance of this imager is further verified by single-photon imaging experiments at a low photon flux down to one detected photon per pixel. This orthogonal time–amplitude-multiplexing readout and corresponding nanowire designs give the most efficient readout compared with previous methods, which would speed up the development of large-scale single-photon imagers for quantum measurements, remote sensing, astronomical telescopes and so on.A 1,024 pixel superconducting nanowire single-photon imager over a detection area of 403.2 μm × 403.2 μm is demonstrated by introducing an orthogonal time–amplitude-multiplexing method. The spatial resolution and average temporal resolution are 12.6 μm and 67.3 ps, respectively.