Microwave single-photon detectors are critical in quantum information processing and dark matter detection. The detector based on a controlled phase (CZ) gate between microwave photons and superconducting qubits has attracted much attention due to its quantum nondemolition (QND) property. However, the practical implementation of such CZ gates and the accurate calibration of detector efficiency remain insufficiently explored. This work presents a comprehensive study on CZ gate implementation and detection efficiency characterization. Theoretically, we derive the condition for π phase shift in the CZ gate and model the measurement-induced dephasing at different parameters. Experimentally, we implement a 3D transmon device, and develop a precise two-stage calibration method for the CZ gate using Josephson Parametric Amplifier’s phase sensitivity. We further introduce an efficiency model separating coupling efficiency and internal detection efficiency, incorporating multi-photon effects during calibration with weak coherent states. Our results provide relaxed CZ gate criteria, an accurate calibration protocol, and a loss quantification framework, advancing practical detector performance.

Directly integrating superconducting nanowire single-photon detectors (SNSPDs) on the fiber facet could significantly reduce coupling loss and alignment uncertainty, enabling an all-fiber single-photon detector with high detection efficiency, robust coupling, and compact size. However, the material and mechanical incompatibility between bulky optical fibers and nano-fabricated ultrathin nanowires makes fabrication and integration challenging. Here, we demonstrate a hybrid integration method that involves fabricating individual membrane-based detectors and optical mirrors separately, followed by their precise assembly on fiber facets. After integration, the detectors exhibit saturated quantum efficiency, a maximum system detection efficiency of 68.6%, a timing jitter as low as 26 ps, and a counting rate of up to 51.7 Mcps. These performance metrics are comparable to SNSPDs on standard silicon wafers. Moreover, this integration enables a fiber facet coupling regime where the detector is embedded in the guide mode of the incident light, resulting in an exceptionally broad detection bandwidth (1310-1640 nm) with less than 2.3% reduction in efficiency. The successful fiber facet integration of SNSPDs not only provides an alternative coupling strategy but also introduces a single-photon detection capability into the group of fiber-integrated optoelectronics, paving the way for low-loss, long-range quantum communication and distributed sensing systems.

For future millimeter/submillimeter and terahertz astronomy, kilo-pixel imaging arrays of ultra-sensitive, background-limited detectors are essential. Given their intrinsic frequency-domain multiplexing and straightforward fabrication, superconducting kinetic inductance detectors (KIDs) are a leading candidate for this purpose. Aluminum, which has a long quasiparticle lifetime, is a crucial material for implementing the sensitive element of a KID. A key figure of merit that quantifies detector sensitivity is the noise equivalent power (NEP). This study compares two characterization methods-small-signal analysis and a frequency-shift response model-for the optical responsivity and NEP of an aluminum-based terahertz KID coupled to a cryogenic blackbody. The KID is a lumped-element, high-Q microwave resonator consisting of a tantalum interdigitated capacitor in parallel with an aluminum inductor, with the latter acting as the 15 THz absorber. The small-signal analysis method, which uses phase and amplitude as observables, requires high precision in blackbody temperature control and involves long measurement times. In contrast, the frequency shift response model method, which uses frequency and dissipation as observables, imposes less stringent requirements on thermometer resolution and enables faster measurements. Moreover, it fits the fractional frequency shift response more accurately than linear models. Consequently, it represents an efficient and rapid approach to characterizing the optical responsivity and NEP of KIDs. With this method, a minimum optical frequency NEP of 7.5 & times;10(-18 )W/root Hz andadissipationNEPof7.1 & times;10(-18) W/ root Hz are achieved for the terahertz KID at 300 Hz, referenced to absorbed power. Furthermore, the frequency NEP significantly exceeds the dissipation NEP at 1, 10, and 100 Hz, which is attributable to two-level system noise. Our work provides valuable technical guidance for the rapid NEP characterization of high-sensitivity terahertz KIDs in low-temperature measurement applications.

Single-photon coincidence counters are essential components in integrated quantum photonics, enabling efficient logic discrimination and real-time error correction at the chip level. However, monolithic integration at cryogenic temperature remains challenging. Here, we demonstrate a coincidence counter based on superconducting nanowire cryotrons (nTron). The circuit comprises five nTron devices, including delay gates, buffer gates, and an AND gate, achieving a maximum bias margin of 22% at a bit error rate (BER) of 10(-5). Operating at 1 MHz, the counter exhibits a static power consumption of 282 nW and a dynamic power consumption of approximately 2 nW at a maximum operation frequency of 17 MHz. The coincidence time window is tunable, with a minimum width below 1 ns, and its position can be adjusted via bias currents. This design offers compatibility with superconducting nanowire single-photon detectors in fabrication and operation, supporting monolithic integration for scalable quantum photonic systems.

Superconducting nanowire single-photon detector (SNSPD) is a high-performance single-photon detector that can be extended to the mid-to long-wave infrared range. It is highly suitable for astronomical observation missions with requirements of a wide observation range, weak signal detection, and low dark count rates. This article introduces optical response models of SNSPD, establishes a connection between SNSPD parameters and astronomical measures, and describes the development of SNSPD in the mid-to long-wave infrared band. It analyzes the research directions and difficulties from the perspectives of materials, fabrications, device structures, optical enhancement structures, and large array size. It discusses the feasibility of its applications in astronomical detection fields, such as Lidar and exoplanet spectral detection. Finally, it summarizes and looks forward to the development direction of mid-to long-wave SNSPD, highlighting the issues that still need to be resolved, such as further wavelength extension, infrared optical enhancement structures, and miniaturization. SNSPD has achieved saturated internal quantum efficiency at 29 mu m, but there is still a far way from realizing megapixel arrays and high-detection efficiency devices. With the advancement of micro-nano processing technology and refrigeration technology, it is accessible to achieve high-efficiency mid-to long-wave SNSPD array devices on satellites.

This study demonstrates an on-chip electrically tunable whispering gallery mode resonator (WGMR) operating in the terahertz (THz) band, fabricated on a silicon platform. The device consists of a micro-ring resonator with integrated platinum electrodes for voltage application. By leveraging the thermo-optic effect of silicon, the resonant frequency of the WGMR is dynamically shifted via Joule heating induced by an applied voltage, enabling continuous electrical tuning of the resonance. Experimental results show a continuous frequency tunability of 0.40 GHz/W, with the resonator exhibiting a measured quality factor (Q-factor) of 199 around 390 GHz. This work provides a compact, integrable, and efficient solution for active resonance control in THz integrated circuits, with promising applications in reconfigurable filters, modulators, sensors, and next-generation wireless communication systems.

Abstract Quantum phase slip (QPS) is the fundamental manifestation of macroscopic quantum tunneling (MQT). We measure the distribution of the switching current I sw in quasi-one-dimensional superconducting NbN nanowires in the temperature range of 0.2–5.1 K. The escape temperature T esc extracted from the I sw distributions exhibits saturation at temperatures below 1.2 K, indicating a transition into the MQT state. We investigate the single-photon response of the nanowire and find that the QPS rate increases with incident light power in the MQT state. We propose the photon-enhanced quantum phase-slip model, which establishes a quantitative relationship between the quantum phase-slip rate and the incident photon energy, generalizing the phase-slip dynamics into the photon-induced non-equilibrium MQT regime.

Superconducting nanocircuits serve as an important platform for realizing quantum computing and quantum detecting. van der Waals integration (vdWI) has been reported in semiconductor devices due to its excellent electrical and thermal properties, but it is rarely reported in superconducting nanocircuits. In this work, we demonstrate a heterostructure through vdWI strategy to achieve the directional control of the thermal relaxation in a superconducting platform. The heterostructure is composed of NbN and MoS2 deposited by chemical and sputtering methods, respectively, thereby constructing a vdWI heterostructure with intrinsic anisotropic thermal conductivity. The simulated results indicate that the temperature uniformity of NbN superconducting nanocircuits was improved by the ultrahigh conductivity in plane of MoS2. The experimental results show that the superconductivity was improved as a transport characteristic curve. The improved superconductivity is benefited from the robustness to self-heating in a vdWI heterostructure, which is applicable to superconductor devices.

Phonons not only serve as the fundamental medium underlying superconductivity but also play a critical role in tuning the performance of superconducting nanowires. Here, we present an efficient approach for detecting midinfrared single photons by leveraging enhanced phonon trapping in superconducting nanowires, which arises from intrinsic acoustic mismatch. In the experiment, the nanowires are patterned on nitrogen-doped amorphous tungsten films, which consist of disordered heavy atoms and weakly doped light atoms. This unique structural composition enables the films to exhibit a phonon group velocity that is significantly lower than that of the silicon substrate. The current-voltage characteristics reveal an ultrahigh ratio of the superconducting switching current to retrapping current (similar to 22), which is more than three times higher than that of conventional niobium nitride nanowires. We attribute the increased ratio to phonon trapping facilitated by strong intrinsic acoustic mismatch. Furthermore, the fabricated detector achieves saturated internal detection efficiencies across a wavelength range 1.75-6 & micro;m. This work provides a facile strategy for improving the sensitivity of midinfrared single-photon detectors through in situ phonon engineering.

A system detection efficiency (SDE) of up to 90% is commonly reported for superconducting nanowire single-photon detectors (SNSPDs) coupled with single-mode fibers at 1550 nm. However, achieving stable and high-performance SDE for practical multimode fiber-coupled SNSPDs at 1064 nm, a wavelength widely used in lidar, remains a significant challenge. This difficulty arises primarily from two factors: first, the backside-illuminated structure, which is designed to focus incident light from fibers onto the photosensitive area of the SNSPD, induces substantial absorption loss in the silicon substrate; second, the nanowire absorption efficiency exhibits pronounced polarization sensitivity, and a front-side-illuminated structure also has relatively limited fabrication process compatibility, which makes it challenging to achieve polarization insensitivity and high SDE. In this paper, we report a backside-etched SNSPD design with improved SDE performance at 1064 nm. Specifically, a titanium dioxide layer was incorporated into the optical cavity to effectively suppress the polarization sensitivity. Concurrently, an additional dry etching step was implemented on the silicon substrate, reducing the silicon substrate's intrinsic absorption loss from 25% to less than 5%. Experimentally, an SDE of 67% was achieved for our sample device at 1064 nm, with the minimum SDE exceeding 64% for all polarization states. This study demonstrates a high-performance solution optimized for 1064 nm, a wavelength offering superior atmospheric transmission and far-field beam characteristics, enabling broad applications in lidar, satellite laser ranging, and industrial manufacturing.

ABSTRACT Terahertz (THz) compressive imaging is fundamentally limited by the absence of practical spatial light modulators capable of implementing native ±1 phase‐mask encoding. Consequently, most existing systems rely on amplitude‐only modulation and complementary measurements to synthesize ±1 masks, thereby doubling acquisition time and reducing measurement efficiency. Here, we present a THz compressive imaging framework based on a liquid‐crystal programmable metasurface that enables direct binary phase modulation for native signed‐mask encoding. This phase‐domain operation eliminates the need for complementary measurements and significantly improves acquisition efficiency. To address the sign ambiguity inherent in amplitude‐only detection, a physics‐guided deep neural network is introduced for robust image reconstruction. Both simulations and experiments demonstrate high‐fidelity imaging at a sampling ratio as low as 37.5%, highlighting a practical route toward efficient and scalable THz computational imaging.

Superconducting diodes enable dissipationless directional transport, yet achieving electrical tunability and scalability remains a major challenge for circuit-level integration. Here, we demonstrate an electrothermal-switch superconducting diode in which a gate-controlled nanoscale hotspot dynamically breaks inversion symmetry in a superconducting nanowire. This mechanism gives rise to two coexisting non-reciprocal transport regimes, one associated with a non-reciprocal superconducting-to-normal transition and the other with ratchet-like vortex dynamics, both originating from the same electrothermal-switch process. The diode exhibits efficiencies up to 42 and 60% for the two regimes, respectively, and can be electrically switched on, off, or reversed in polarity in situ by applying a small gate current. These capabilities enable programmable superconducting circuits that realize electrically reconfigurable full-wave and half-wave rectification. The lithography-compatible design, high performance, and gate-controlled functionality establish a scalable platform for programmable superconducting electronics and hybrid quantum systems.

Superconducting diodes, which exhibit nonreciprocal critical currents, are promising building blocks for low-power cryogenic electronics and superconducting circuits. Existing superconducting diode platforms commonly rely on Josephson junctions, multilayer heterostructures, ferromagnetic elements, gate-difined structures. Here, we demonstrate a geometrically induced superconducting diode effect realized in a structurally minimal, single-materials NbN nanoring, where inversion-symmetry breaking is introduced solely by the asymmetric geometry. The device exhibits pronounced and polarity-switchable critical-current nonreciprocity. Systematic magnetic-field and temperature-dependent measurements reveal that, at low fields, the applied magnetic field redistributes the critical current asymmetrically between opposite bias directions without significantly reducing the overall superconducting current-carrying capability. Moreover, the maximal nonreciprocity and diode efficiency exhibit distinct temperature dependence: the maximal diode efficiency follows the evolution of the energy gap, whereas the maximal nonreciprocity is more closely associated with the superfluid density. These results establish asymmetric superconducting nanorings as a minimal geometric platform for studying nonreciprocal superconducting transport and provide a simple design principle for future superconducting electronics.

We report a molybdenum superconductor with a transition temperature exceeding 6 K by heteroatom-doping engineering approach, named nitrogen-doped amorphous molybdenum (NAM). In conventional superconductors, electron pairing is mainly attributed to the electron-phonon interactions among the lattice. However, the amorphous molybdenum superconductor without a repeating atomic arrangement produces an increased superconductivity. Furthermore, the stability was verified by the treatment in organic solvents and deionized water, showing promising applications in superconductor devices. As a demonstration, the NAM-based superconducting nanowire single-photon detector exhibits a saturated quantum efficiency (approaching 100%) at an operating temperature of 2.1 K which can be reached by Gifford-McMahon refrigerators.

Superconducting nanowire geometry has been widely adopted in single-photon detectors. However, its commonly used planar process limits the improvement of performance and the expansion of functionality. In this study, a three-layer stacked superconducting nanowire detectors and its corresponding fabrication process are proposed and implemented. The superconducting layers are composed of nitrogen-doped amorphous tungsten (NAW), whereas the dielectric layers are made of Nb5N6. Optimized precise etching control and “overhang” electrode filling were applied to achieve high-precision interlayer interconnection and uniform device fabrication. The experimental results show that the three-layer structure results in a critical current (Ic) of 7.2 μA, which is approximately three times greater than that of a single-layer structure, along with a 2.7× enhancement in the peak response, a 57% reduction in the pulse width (full width at half maximum), and a 2.2× improvement in the signal-to-noise ratio (SNR). Three distinct saturation plateaus observed in the photon count rate–bias current curve confirm the interlayer thermal coupling mechanism, which is consistent with the derived n-layer thermal model. This work provides a structural paradigm and scalable fabrication process for high-performance superconducting nanowire detector arrays, offering promising prospects for advanced quantum information processing and integrated photonic quantum technologies.

The hybrid cavity optomechanical system can exhibit various remarkable optical effects under appropriate coupling conditions. We investigate the optomechanically induced transparency phenomena in a system driven by the probe and pump fields, comprising three optical cavities and a mechanical resonator. The triple optomechanically induced transparency is observed in the absorption spectrum by adjusting the system parameters. The characteristics of OMIT can be controlled through coherent interactions, either among optical modes or between optical and mechanical modes. Specifically, the transparency windows increase in number and width with higher coupling constants, whereas the absence of coupling reduces window count and shifts the two outermost points outward. Additionally, we delve into the phenomenon of slow/fast light associated with rapid phase changes in the probe field, which realizes the conversion from slow to fast light. We also explore the properties of optomechanically induced transparency in extended four- and five-cavity systems, which show four and five transparency windows, respectively. Generalizing this to an N-cavity system reveals the presence of up to N transparency windows. Collectively, these results provide valuable insights for photon regulation and contribute to the advancement of nonlinear optical systems.

The high-temperature superconductor Bi2Sr2CaCu2O8+delta (BSCCO) single crystal devices, with their unique intrinsic Josephson junction array structure, have demonstrated remarkable research value and application potential over the past three decades. In the past five years, the field has achieved breakthrough progress, showing a diversified development trend, with significant results in fabrication technology, terahertz radiation technology, detection technology, and emerging applications, etc. In terms of fabrication technology, the collaborative innovation of two-dimensional material fabrication technology and micro/nano fabrication technology has driven a breakthrough in the fabrication technology of BSCCO single crystal devices. This paper systematically elaborates on the challenges to be addressed, fabrication process flow, core competitive advantages, and application scenarios of each core technology. The successful application of cryogenic dry transfer technology has achieved lossless transfer of atomic-level thickness materials, laying a solid foundation for the preparation of high-quality BSCCO single-crystal devices. The silicon nitride hard mask and room-temperature high-vacuum in-situ evaporation technology have established an electrode preparation process system suitable for multiple scenarios, significantly improving the stability and success rate of sample preparation. The introduction of localized metal deposition technology and focused helium ion beam irradiation technology has achieved precise control of nano-scale lattice structures, providing key technical support for further improving device performance, marking the entry of high-temperature superconducting electronic device fabrication technology into a new stage. In addition, this paper introduces breakthroughs in the application expansion of BSCCO crystal devices in detail. In the field of terahertz radiation technology, performance optimization and technological innovation have shown potential in communication transmitter applications, providing new possibilities for the development of terahertz communication technology. In the field of detection technology, the technological barrier of integrating an intrinsic junction and antenna structure integration has been overcome. Researchers successfully developed a high-temperature superconducting probe microscope system, which provides an innovative solution for chip characterization. It is noteworthy that emerging applications exhibit stronger interdisciplinary characteristics. For example, the infrared superconducting single-photon detector operating at 25 K has broken through the working temperature limitations of traditional low-temperature superconducting detectors, offering a new high-sensitivity solution for national strategic fields such as deep-space communication. At the same time, the rapid development of high-temperature superconducting diodes and the proposal of new quantum bit theoretical models have not only enriched the theoretical framework of high-temperature superconducting electronics but also built a bridge for technological collaborative development with frontier fields such as quantum information and weak signal detection, promoting the deepening of interdisciplinary integration. Finally, this paper discusses future research directions for devices in this material system. The above breakthrough achievements have not only laid a solid foundation for the practical application of high-temperature superconducting electronics in terahertz technology, but also opened up new paths for frontier fields such as deep-space communication, low-power logic circuits, and quantum computing, etc. These technological advancements have not only promoted the expansion of application scenarios such as cross-scale integration and multi-physical field coupling but also demonstrated the broad application prospects and continuous development vitality of high-temperature superconducting electronics in the context of interdisciplinary integration.

Superconducting nanowire single-photon detectors (SNSPDs) have demonstrated saturated quantum efficiency in the long-wave infrared spectrum by reducing the thickness and the critical temperature of the film. However, the ultrathin film has finite light absorption, limiting the detection efficiency of the detector without an optical cavity. At long-wave infrared wavelengths, most oxide dielectrics exhibit significant optical absorption, and the required cavity length also increases, posing additional design and fabrication challenges. In this work, a silicon membrane-based optical cavity fabricated on a silicon-on-insulator (SOI) substrate is proposed to address these issues. Meanwhile, a free-space coupling system has been built for characterizing the device response spectrum. The superconducting nanowire, made from 5 nm thick WSix film with a reduced critical temperature of 2.5 K, exhibited saturated quantum efficiency from 7.8 to 12.5 μm. The detector's detection efficiency reached a resonance peak at 11.19 μm and a maximum value of 39.7%, which was in agreement with the design. Background counts were found mainly from the room-temperature blackbody radiation photons, which were reduced to 4 cps after shielding the detector in a vacuum. Correspondingly, the minimum noise equivalent power of 1.06 × 10-19 W·Hz-0.5 was obtained. These results demonstrate that the silicon membrane cavity not only preserves the superconductivity of the nanowire but also functions as an effective optical resonator. Therefore, it offers a promising platform for enhancing the sensitivity of SNSPDs in the long-wave infrared range.

Superconducting diodes, enabling nonreciprocal supercurrents, hold promise for dissipationless electronics and time-reversal-symmetry-broken physics. Developing platforms that combine high-temperature operation with scalable fabrication remains a critical challenge for the field. Here, we show that the intrinsic Josephson junctions naturally in the layered cuprate Bi2Sr2CaCu2O8+δ offer a robust, lithography-compatible platform for high-temperature superconducting diodes. By controlling the number of naturally stacked junctions, we achieve tunable nonreciprocity, with single-surface junctions exhibiting peak efficiency and programmable zero-field memory states. A microscopic model attributes this behavior to geometry-induced anharmonicity in the current-phase relation, amplified by atomic-scale barriers. Moreover, by exploiting the natural junction architecture, we fabricate arrays containing hundreds of reproducible diodes. By uniting high-temperature operation with scalability and programmable functionality, intrinsic Josephson diodes establish a practical route toward superconducting electronics and open new avenues of nonreciprocal superconducting transport.

On-chip filters are important for integrated terahertz (THz) communication and sensing systems. Deterministic control of resonance multiplicity in compact devices enables flexible spectral filtering. Here, we experimentally demonstrate an on-chip silicon THz filter based on a Bragg-grating-assisted Fabry–Pérot cavity, in which the resonance multiplicity is governed by the relation between the Bragg stopband and the cavity free spectral range (FSR). By engineering this stopband–FSR relation, single-, double-, and triple-resonance states are achieved within the 360–390 GHz band, with a packaged insertion loss of approximately 6 dB. The single-resonance device exhibits a through-port transmission minimum approaching −40 dB and a loaded quality factor of QL = 809.5. This work provides a compact strategy for deterministic spectral-state engineering in integrated THz filters.