Physics

Bacterial biofilms fuel antimicrobial resistance, a pressure amplified by repeated deployment of structurally uniform bactericides. Photoswitchable azobenzenes offer light-driven structural diversity that may temper resistance evolution, but their small-molecule form limits foliar adhesion. Although supramolecular materials show promise as biofilm inhibitors, photoresponsive supramolecular polymers for this purpose remain largely unexplored. This study reports Azo@CB[8], a multifunctional supramolecular polymer that self-assembles in water from a de novo azobenzene (Azo) and cucurbit[8]uril (CB[8]). CB[8]-mediated association preserves photoisomerization, improves cycling stability, and integrates membrane disruption, redox imbalance, biofilm inhibition, sessile-cell killing, and enhanced foliar affinity. In pot assays, Azo@CB[8] outperforms free Azo and thiodiazole copper against rice bacterial leaf blight, without detectable biosafety penalties, and likewise exceeds both controls against kiwifruit bacterial canker. Notably, photoisomerization perturbs azobenzene-mediated host-guest interactions while largely retaining bipyridinium-CB[8] association, thereby reducing supramolecular connectivity and driving reconfiguration of the extended architecture into a smaller, less-connected supramolecular ensemble. The photoirradiated supramolecular state retains antibacterial efficacy comparable to that of the initial assembly. Together, these findings outline a supramolecular polymer-based, photoregulated route to greener management of bacterial plant diseases.

ABSTRACT The intrinsically weak nonlinear optical response of existing materials, further constrained by symmetry‐forbidden second‐order processes in centrosymmetric media, severely limits efficient frequency conversion in deeply subwavelength, ultrathin volumes. Addressing this challenge is crucial for the development of nonlinear nanophotonics. Here, we show that atomically thin, epitaxially grown crystalline silver films circumvent these restrictions through the interplay of vertical electronic quantum confinement and lateral plasmonic enhancement. We fabricate atomically thin films that exhibit an enhanced nonlinear response associated with electronic quantum wells, and subsequently pattern them into periodic nanoribbon and nanotriangle arrays sustaining infrared localized surface plasmon resonances. Strong near‐field confinement in these structures further boosts second‐harmonic generation compared to unpatterned films. Precise control over nanostructure geometry enables spectral tuning of the plasmonic resonance, and consequently, the enhanced harmonic frequency. Our findings establish an approach for activating robust second‐order nonlinearities in quantum‐confined metals, where intrinsic size effects and plasmonic resonances act synergistically. The compatibility of high‐quality epitaxial growth with microchip fabrication technology offers a scalable route toward ultracompact nonlinear optical components for on‐chip frequency conversion, sensing, and quantum photonic applications.

Abstract For compact fusion superconducting magnets, accurately reconstructing the critical current response surface of REBCO coated conductors is crucial, as it directly affects current margin evaluation, stability analysis, and quench modeling, especially at 20 K, a critical temperature balancing high field current carrying capacity and low temperature load. However, complete angular critical current measurements under strong magnetic fields at 20 K are costly, resulting in practical datasets that are usually dominated by dense low and medium field data, while high field data remain sparse. This work proposes a physics-informed hybrid modeling framework that combines an anisotropic effective-field physical framework with a gated neural residual correction for sparse-anchor-constrained critical current response surface reconstruction. The method is evaluated using two REBCO coated conductor data under interpolation, strict extrapolation, sparse-anchor-assisted reconstruction, shape-sensitive diagnostics, and 20 T sparse-anchor consistency analysis. The results show that the hybrid framework improves reconstruction performance in several key settings and maintains more physically reasonable high field angular behavior than other baseline model under sparse supervision. The proposed method offers a practical route for constructing 20 K critical current response surfaces when complete high field angular characterization is unavailable.

Abstract Superconducting vector magnets can generate steady, controllable magnetic fields in three-dimensional space and have gradually become an important approach for realizing high-field vector magnetic environments in advanced scientific applications. As a key external-field parameter in frontier research areas such as quantum computing, strongly correlated electron systems, topological phases of matter, and spintronic devices, vector magnetic fields are subject to increasingly stringent requirements in terms of field magnitude, directional control accuracy, and operational stability. Compared with sample rotators, permanent-magnet arrays, and pulsed vector magnets, superconducting vector magnets offer significant advantages in high field strength, high field homogeneity, long-term stable operation, and compatibility with cryogenic environments. This paper provides a systematic overview of mainstream approaches to vector magnetic field generation, with a particular focus on superconducting vector magnets. First, the major schemes for generating vector magnetic fields are classified and compared, and their performance limits and applicable scenarios are analysed. Second, the electromagnetic design theories of representative superconducting vector magnet topologies are reviewed. In accordance with the chronological sequence of their development, the core logic and theoretical foundations of each design theory are introduced, the characteristics and performance of typical topologies under each design theory are evaluated, and the evolutionary trends in superconducting vector magnet design theory are summarized. Finally, the key technical challenges facing the future development of superconducting vector magnets are discussed. This paper aims to provide a systematic reference for the design and application of high-performance superconducting vector magnets.

Abstract The fourth-generation ECR ion source magnet (FECR), the CSR external-target experiment magnet (CEE), and other low-temperature superconductor (LTS) magnets developed at the Institute of Modern Physics (IMP) and applied in accelerator facilities are subject to frequent voltage disturbances, such as those induced by flux jumps. These disturbances can closely resemble genuine quench signals, thereby posing a significant challenge to conventional parametric quench detection methods. To suppress false triggers, existing methods typically employ extended detection windows, which increase detection latency and reduce the available protection margin. To address this challenge, a deep learning–based quench detection method is proposed for LTS magnets operating under complex electromagnetic conditions. A dedicated neural network is developed to extract discriminative features from voltage signals and is deployed as an Artificial Intelligence Quench Detection System (AI-QDS) to enable real-time online quench detection. The system was further validated online during excitation tests of the HIAF-FECR superconducting magnet prototype No. 2 (HFECR-2#). During excitation toward the design current, three quench events occurred and were successfully detected online by the AI-QDS. Compared with a conventional parametric quench detection system, the proposed method reduced the detection latency by 9.6 ms, 32.0 ms, and 99.6 ms, respectively, while maintaining robust operation under strong electromagnetic disturbances. These results demonstrate the feasibility and effectiveness of deep learning–based online quench detection for LTS magnets. This method also provides a promising approach for intelligent protection of high-field Nb3Sn superconducting magnets and offers potential applications in future accelerator and fusion facilities.

Abstract The reliable fabrication of high-sensitivity superconducting quantum interference devices (SQUIDs) with high critical transition temperature (high-T c ) is crucial for many practical applications such as weak magnetic sensing. In this work, we report the first realization of the YBa 2 Cu 3 O 7-δ radio frequency superconducting quantum interference devices (rf SQUIDs) based on focused helium ion beam (FHIB) technique. A series of YBCO rf SQUIDs with high consistency were fabricated using a 30 keV FHIB with different helium ion (He + ) dose. The dose dependent characteristics of the fabricated devices were systematically investigated at a temperature of 77 K. The experimental results verify that the variation in He + dose can effectively modulate the junction parameters and thereby the device noise performance. A non-monotonic white noise trend with increasing He + dose was observed, which could be primarily attributed to the transition of operational working regime of the fabricated rf SQUIDs. Based upon the dose optimization, a flux noise of 58 μΦ 0 /Hz 1/2 , corresponding to a field sensitivity of 185 fT/Hz 1/2 , was achieved with our current device configuration. Approaches to further optimize the overall device performance are also discussed. Our work demonstrates FHIB-based high-T c SQUIDs with high junction parameter consistency a promising candidate for the implementation of multi-channel weak magnetic field detection systems and might hopefully serve as a platform for validating the theoretical models of high-T c SQUIDs.

Abstract Considering systematically derived energy-transfer-dependent effective electron-electron interactions leads to the appearance of secondary phase and amplitude modes in isotropic superconductors in the intermediate-to-strong-coupling regime. We study the implications of such interactions on Bravais lattices by computing the corresponding response functions using the iterated equations of motion (iEoM) approach. In the weak-coupling regime, we find the conventional, primary amplitude and phase modes at ω = 2∆ and ω = 0, respectively. For intermediate coupling, the amplitude mode detaches from the quasiparticle continuum towards lower energies. Increasing the coupling further leads to additional, long-lived secondary collective excitations below the continuum. This phenomenon is largely independent of the underlying lattice and the specific Fermi level. The amplitude and phase modes couple if the system is not particle-hole symmetric. Additionally, we extend the method to compute eigenoperators, i.e., linear combinations of operators that excite each secondary mode specifically. We identify nodal structures in the coefficients for these eigenoperators reminiscent of wave functions in the Hydrogen problem.