Nonlocal connectivity is a critical resource for universal logical quantum gates and low-overhead quantum error correction codes, and is unavailable on current superconducting devices with nearest-neighbor connections. To rectify the deficiency in connectivity of superconducting circuit systems, we experimentally demonstrate a convenient on-chip coupler of centimeters length and with quality factor close to 1 & times; 106. The entangling gate is performed between two fluxonium qubits, reaching a fidelity of 99.37% within 120 ns, while the system static ZZ interaction rate remains as low as 144 Hz without active cancellation or circuit parameter targeting. This high-fidelity low-crosstalk nonlocal coupler can be the building block of a binary-tree connectivity graph, reducing the average qubit entangling distance from O(N) to O(log2 N). With the high-fidelity nonlocal entanglement, novel quantum algorithms can be implemented on the superconducting qubit system, positioning it as a strong competitor to other physics systems regarding circuit connectivity.

Period-doubling bifurcation, a crucial route from steady states to chaos in nonlinear dynamical systems, exhibits unique characteristics in laser optics. However, its underlying mechanisms in nonlinear amplifying loop mirror lasers remain incompletely understood. Here, a variational model based on energy transmission and Poincar & eacute; map is developed, unraveling that gain-induced nonlinear phase difference between bidirectional pulses trigger bifurcations and validating the existence of 2-based cascaded periodic states and chaos. Experimentally, an erbium-doped passively mode-locked figure-of-9 laser enables experimental observation of a complete cascaded bifurcation route. Furthermore, phenomena new to our knowledge are identified, including the statistical characteristics of chaos and spectral pulsations. These findings not only expand the understanding of nonlinear dynamics, but also offer valuable insights for applications such as metrology, telecommunication, and frequency comb.

Laser Doppler velocimetry is a powerful method for precise motion monitoring with the advantages of high precision and noncontact. Among them, self-mixing (SM) laser Doppler velocimetry exhibits high sensitivity for noncooperative targets. The spontaneous amplification of Doppler signals through intracavity interference enables the detection of weak echo signals, meeting practical measurement requirements. However, the frequency-dependent gain profile in laser feedback systems exhibits progressive attenuation at higher frequencies due to the inherent gain-frequency constraint, fundamentally limiting their applicability for high-sensitivity velocimetry of high-speed targets. We quantitatively establish for the first time, to our knowledge, that the product of self-mixing interferometry’s gain and frequency (GFP) remains constant for higher frequency. In order to improve the bandwidth of SM laser Doppler velocimetry and further enhance the sensitivity of self-mixing interferometry (SMI), a frequency conversion method is implemented to transcend this intrinsic limit. The electro-optical modulator (EOM) and optical injection locking are employed to shift the frequency of the interference signal into the gain region, enabling the extension of gain bandwidth. Theoretically, the measurement bandwidth of Doppler frequency can extend to tens of GHz (the corresponding speed beyond 1 km/s at 1550 nm) due to the large modulation bandwidth of EOM, and the experimental measurement of Doppler frequency exceeds 44 MHz (34.1 m/s at 1550 nm) limited by the target. The system achieves a Doppler frequency measurement precision within 4 Hz. In the meantime, optical injection locking can provide additional optical gain. The seed light of 10 μW is amplified to 60 mW, providing a gain of 37 dB. The detection limit of the proposed system is −145.52 dB with 10 4 higher intensity response sensitivity than normal heterodyne interference. Therefore, the system has the advantages of large bandwidth, high sensitivity, and high precision. It is expected to be widely used in the monitoring of noncooperative high-speed moving targets.

We propose and experimentally demonstrate a global parametric gate that generates multi-qubit entangled states in a single step. By applying a parametric drive to a common qubit at precise detunings relative to computational qubits, we directly produce two-, three-, and four-qubit entanglement with state fidelities of 99.4%±0.2%, 93.4%±0.3%, and 91.4%±0.3%, respectively. This scheme enables efficient, reconfigurable control using only microwave drives and is compatible with fixed-frequency qubits. Error analyses indicate that infidelity stems primarily from decoherence and coherent control errors, with negligible contributions from static ZZ coupling and flux noise. Furthermore, simulations with state-of-the-art parameters predict this global gate can generate high-fidelity (99.70%) entanglement in systems of up to six qubits.

The measurement speed of conventional fiber grating sensing systems is limited by the wavelength scanning procedure of spectrometer-based demodulation modules, which makes it impossible to satisfy the demands of real-time monitoring. To address this limitation, this paper proposes a real-time sensing scheme that adopts a mode-locked erbium-doped fiber laser (ML-EDFL) as the light source for fiber Bragg grating (FBG) temperature and stress monitoring. The proposed scheme utilizes the output spectral characteristics of the ML-EDFL, namely the deterministic mapping correlation between transverse optical frequency (wavelength) and longitudinal power, thereby transforming frequency-domain wavelength scanning into high-speed acquisition of time-domain power signals to realize rapid demodulation of sensing parameters. On this basis, a nonlinear polarization rotation based ML-EDFL is constructed, with the output pulse featuring a central wavelength of 1560.02 nm and a repetition frequency of 23.04 MHz. Furthermore, an FBG-based real-time temperature and stress sensing system is developed and subjected to real-time measurement tests, achieving sensitivities of 20.8 nW/°C for temperature and 113.85 nW/MPa for stress, respectively. The experimental results demonstrate that the proposed method and sensing system can implement high-speed real-time monitoring of FBG sensing parameters, manifesting favorable applicability in dynamic temperature and stress measurement applications.

Selective Laser Melting (SLM) has shown great potential in the design and fabrication of complex metallic components. However, SLM-fabricated parts generally suffer from poor surface quality, resulting in inferior fatigue performance. Although post-treatments such as heat treatment (HT) and machining are commonly applied, their effectiveness is limited for complex geometries or narrow regions. In this study, a rapid surface modification method by micro-scale laser shock peening without coating (mu LSPwC) is proposed to improve the surface quality and fatigue performance of SLM-fabricated GH3625 Ni-based superalloy. The surface characteristics and fatigue performance of the SLMed, HT + polished, LSP, LSPwC and mu LSPwC treated specimens are compared. Results indicate that mu LSPwC effectively reduces surface roughness from 7.75 mu m to 5.63 mu m through micro-scale laserinduced thermal effect. Simultaneously, the mechanical effect of the laser-induced shock wave introduces a compressive residual stress (CRS) layer with a depth of approximately 340 mu m and a hardened layer of about 245 mu m. Moreover, the average grain size in the near-surface region is refined from 69.04 mu m to 41.51 mu m. As a result, the mu LSPwC specimen exhibits the most pronounced improvement in fatigue performance, with a fatigue life approximately 41.7 times longer than SLMed specimens.

Laser Doppler velocimetry is a powerful method for precise motion monitoring with the advantages of high precision and noncontact. Among them, self-mixing (SM) laser Doppler velocimetry exhibits high sensitivity for noncooperative targets. The spontaneous amplification of Doppler signals through intracavity interference enables the detection of weak echo signals, meeting practical measurement requirements. However, the frequency-dependent gain profile in laser feedback systems exhibits progressive attenuation at higher frequencies due to the inherent gain-frequency constraint, fundamentally limiting their applicability for high-sensitivity velocimetry of high-speed targets. We quantitatively establish for the first time, to our knowledge, that the product of self-mixing interferometry's gain and frequency (GFP) remains constant for higher frequency. In order to improve the bandwidth of SM laser Doppler velocimetry and further enhance the sensitivity of self-mixing interferometry (SMI), a frequency conversion method is implemented to transcend this intrinsic limit. The electro-optical modulator (EOM) and optical injection locking are employed to shift the frequency of the interference signal into the gain region, enabling the extension of gain bandwidth. Theoretically, the measurement bandwidth of Doppler frequency can extend to tens of GHz (the corresponding speed beyond 1 km/s at 1550 nm) due to the large modulation bandwidth of EOM, and the experimental measurement of Doppler frequency exceeds 44 MHz (34.1 m/s at 1550 nm) limited by the target. The system achieves a Doppler frequency measurement precision within 4 Hz. In the meantime, optical injection locking can provide additional optical gain. The seed light of 10 mu W is amplified to 60 mW, providing a gain of 37 dB. The detection limit of the proposed system is-145.52 dB with 104 higher intensity response sensitivity than normal heterodyne interference. Therefore, the system has the advantages of large bandwidth, high sensitivity, and high precision. It is expected to be widely used in the monitoring of noncooperative high-speed moving targets. (c) 2026 Chinese Laser Press

Bulk inorganic semiconductors can show remarkable plasticity and extensibility, defying their inherent brittleness and enabling opportunities in advanced semiconductor manufacturing and processing.

The continuous catalytic reforming heating furnace is a large-scale system that provides consistent and stable heat support for catalytic reactions. Real-time, in situ and simultaneous measurement of carbon monoxide (CO) and oxygen (O-2) is essential for optimizing its performance. Here, we present a highly sensitive CO/O-2 sensor based on calibration-free wavelength modulation spectroscopy (WMS) for application in a 10-m-long large-scale continuous reforming heating furnace. The first harmonic-normalized second harmonic WMS (WMS-2f/1f) technique and a time-division-multiplexed strategy were employed to address the challenges of harsh industrial environments. A single-ended configuration with a retroreflector and a through-hole parabolic mirror effectively doubled the optical path while simplifying the sensor setup, providing a novel solution for monitoring large-scale heating furnaces. The sensor demonstrated detection limits of 0.3 ppm and 0.04% for CO and O-2, respectively, achieving high sensitivity at high temperature around 850 K. Long-term in situ monitoring confirmed the sensor's reliability in detecting CO and O2 concentrations. Observational data further revealed several instances of incomplete combustion process lasting for 1-2 h, caused by fluctuations in fuel supply. These findings highlight the significant potential of the proposed laser absorption-based gas sensor to enhance heating furnace control, contributing to improved economic efficiency, environmental protection, and operational safety.

The impact of external light on dislocation‐based plasticity in inorganic compound semiconductors has been increasingly recognized. Here, we investigated the effect of light on the dislocation behavior in wurtzite GaN oriented for basal slip using photoindentation. Two types of nanoindentation tests were performed in darkness and in 380 nm light on GaN single‐crystal substrates oriented to maximize the Schmid factor for the basal slip. Distinct pop‐in events were observed in the loading segment at loads of 150‒340 . Analysis of the first pop‐in events revealed that they correspond to homogeneous dislocation nucleation and are largely unaffected by light irradiation. Indentation creep tests at 2 mN showed that both creep depth and creep strain rate decreased in 380 nm light. Cross‐sectional ultra‐high voltage electron microscopy images taken beneath the indentation imprints displayed an asymmetric dislocation distribution with the majority aligned along the direction. A significant reduction in the density of indentation‐induced dislocations in 380 nm light was observed, indicating that light irradiation effectively suppresses dislocation glide motion and multiplication in GaN for basal slip.

Anisotropy plays a crucial role in understanding and optimizing the properties of materials with directional dependencies. The hexagonal wurtzite structure, which is a typical crystal structure in compound semiconductors, demonstrates pronounced anisotropy, especially in its response to external stimuli. Recently, mechanical behavior under light illumination has attracted increasing interest especially in semiconductor compounds. In this study, we investigated the anisotropy of illumination effects on the nanomechanical properties of wurtzite ZnO. Four surface orientations—(0001), (0001) 45° off, (11¯00), and (21¯1¯0)—were subjected to nanoindentation creep and nanoindentation hardness tests under controlled light illumination. The indentation depth during nanoindentation creep under light illumination was consistently smaller than that in darkness for all surface orientations, confirming that light suppresses indentation creep deformation, but to different degrees depending on the surface orientation. This suggests that the activated slip systems and the distribution of dislocations play a crucial role in modulating dislocation behavior under light illumination. The nanoindentation hardness followed the trend on the four surface orientations: (0001) > (0001) 45° off > (11¯00) > (21¯1¯0), reflecting anisotropic behavior in nanomechanical properties. Second and subsequent pop-in events were extracted, exhibiting different behaviors depending on the surface orientations, and may play a key role in determining the anisotropy in nanoindentation hardness. Our findings contribute to a comprehensive understanding of the plastic anisotropy under light control in wurtzite ZnO.

Strong radiative coupling between two quantum emitters enables the reversible and coherent excitation exchange, while most photonic and plasmonic nanostructures to mediate quantum emitters are inflexible in implementation. We propose a silver line-arc nanowire to realize the strong radiative coupling between two quantum emitters with arbitrary transition wavelength, position and dipole orientation. The resonant wavelength can be remarkably tuned on demand by adjusting its length and diameter. The resonant wavelength, cavity mode, local coupling strength, transfer rate and evolution spectrum are rather robust against its bending. These findings provide significant guidance for the implementation of strong radiative coupling and facilitate quantum information processing.

Cameras have become indispensable sensors in intelligent vehicles, with their deployment steadily increasing across modern automobiles. It is critical for camera modules to have reliable and accurate environmental perception, but a major challenge is condensation inside the modules that severely compromises imaging quality. To address this issue, we performed comprehensive thermodynamics-based simulations to clarify condensation mechanisms and evaluate their impact on optical imaging performance. Based on these insights, we proposed an integrated optical–structural optimization strategy that reduces the internal cavity volume adjacent to the first lens, simultaneously increasing the first lens thickness and the curvature of its internal surface. This strategy both reduces water vapor volume and elevates the temperature of potential condensation zones. The optimized module exhibits markedly improved resistance to condensation compared with the baseline design in the experiment, raising the critical condensation threshold from a sudden temperature drop of 42 °C to over 60 °C. This approach effectively mitigates condensation under harsh environmental conditions without additional cost. Our simple yet effective design is broadly applicable to diverse automotive camera module architectures, thereby enhancing system reliability and improving the overall safety of autonomous driving.

Tilt-to-length (TTL) coupling is a technical term for the cross-coupling of angular jitter into an interferometric length (phase) signal. It is an important noise source in spaceborne gravitational wave interferometers (SGWIs). In this paper, we build a transponder-type laser interferometer to simulate the SGWI. By introducing a tilt between the detector and the beams, the first-order terms in the lever effect and the piston effect cancel each other out, and the first-order TTL coupling is successfully suppressed without accurately measuring the lever length and lateral offset. We suppress the second-order TTL coupling by an imaging system consisting of concave and convex lenses. The parasitic length change of the tilt actuator is compensated by the optical phase-locked loop and the environmental perturbations is removed by the reference photodetector and coherent filtering. The TTL coupling coefficient is below 5 mu m/rad in the range of +/- 300 mu rad, meeting the requirements of Laser interferometer space antenna (LISA) and Taiji. The experimental results could also have implications for the TTL coupling of other interferometers.

A transponder-type laser interferometer is built to simulate tilt-to-length coupling in spaceborne gravitational wave interferometers. Intentional tilt of the detector and imaging system are used to suppress first-order and second-order TTL coupling.

Brillouin microscopy has been widely used in the mechanical imaging of cells and tissues, and the signal-to-noise (SNR) ratio limits the spectral integration time. Impulsive stimulated Brillouin scattering (ISBS) microscopy is a new elastic imaging technique. As a variant of stimulated Brillouin scattering (SBS), ISBS can overcome the weak signal of spontaneous Brillouin scattering. A simple model can estimate SBS gain. However, the theoretical ISBS gain has not been compared with SBS gain. This paper gives the theoretical ISBS gain estimation, and experiments are designed to verify estimation reliability. The heterodyne ISBS gain coefficient can be much higher than SBS gain coefficient. The relationship between ISBS gain coefficient and spatial resolution is then discussed. We anticipate that the ISBS setup optimization can improve spatial resolution and gain, potentially enabling fast and high spatial resolution imaging of biological cells.

The nanoindentation method is a widely utilized approach for characterizing the mechanical properties of materials at the nanoscale. In typical nanoindentation tests, the mechanical responses of materials are monitored while maintaining constant environmental factors, such as lighting and temperature, in order to ensure the reliability of the results. Here, we propose a testing method that switches the light conditions during a single nanoindentation creep test to detect slight changes in the mechanical response due to weak light illumination. To achieve this, a reference sample of fused silica was employed, which is insensitive to light, in order to compensate for the thermal expansion/contraction of approximately 1 nm due to the light environment. The calibrated results revealed the instantaneous suppressive influence of light illumination on the indentation creep behavior of ZnO. It was found that upon initiating illumination, the indentation creep rate decreased by 45%, whereas terminating illumination led to a dramatic 19.4-fold increase in the creep rate. The effective testing pattern involving a "light switch" enables quantitatively visualizing the light illumination effects through the instant "jump" in the creep strain rate within a single test, facilitating the detection of minor and instantaneous effects of light environments on indentation creep behavior.

Bound solitons, as an interesting physical phenomenon operating at multi-pulse mode, are intensively investigated in unidirectional mode-locked lasers, both theoretically and experimentally. However, they have rarely been observed in bidirectional lasers, especially the bound solitons with anti-phase and in-phase have not even reported. Here, we demonstrate a systematic experimental observation of two-soliton bound states with phase differences of 0 (in-phase), +/-pi/2, and pi (anti-phase). The laser is passively mode-locked by a carbon nanotube saturable absorber, with the unsaturated loss, saturation optical intensity, and modulation depth of 40 MW/cm(2), 52.3%, and 6.1%, respectively. Two synchronous single-soliton pulses in clockwise and counter-clockwise directions, with a repetition frequency of 63.92 MHz, were delivered simultaneously from the fiber laser. Besides, various two-soliton bound states with different pulse separations and phase differences were obtained when the pump power was up to 68 mW. Furthermore, not only the same, but also the different bound states were observed between the counter-propagation directions. The short-and long-term stability of the bound states were also investigated in laboratory environments. The results enrich the content of nonlinear dynamics of bound solitons and have potential applications in fiber optical communications.

Quantum error correction codes with non-local connections such as quantum low-density parity-check (qLDPC) incur lower overhead and outperform surface codes on large-scale devices. These codes are not applicable on current superconducting devices with nearest-neighbor connections. To rectify the deficiency in connectivity of superconducting circuit system, we experimentally demonstrate a convenient on-chip coupler of centimeters long and propose an extra coupler layer to map the qubit array to a binary-tree connecting graph. This mapping layout reduces the average qubit entangling distance from O(N) to O(logN), demonstrating an exponentially enhanced connectivity with eliminated crosstalk. The entangling gate with the coupler is performed between two fluxonium qubits, reaching a fidelity of 99.37