The time-of-flight high-resolution neutron diffractometer (TREND) at the China Spallation Neutron Source (CSNS) has been successfully equipped with a large-area $^{3}$He tube array neutron detector, designed to achieve exceptional resolution and uniformity. The detector system, comprising 14 banks and 134 modules with 1376 $^{3}$He tubes, is optimized for high-angle and medium-to-low-angle measurements. Advanced dual-end readout electronics ensure precise charge and time-of-flight measurements, while rigorous performance testing confirmed the system's spatial resolution and uniformity. In-situ testing using polyethylene samples validated the detector's operational stability, with counting rate deviations within 3.7%. The system also demonstrated excellent two-dimensional imaging capabilities and adaptability to various neutron wavelength ranges through harmonic division techniques. These results highlight the TREND detector system as a robust and versatile tool for high-resolution neutron diffraction studies.

The rapid growth of neutron flux has driven the development of $^{3}$He-free neutron detectors to satisfy the requirements of the neutron scattering instruments under construction or planned at the China Spallation Neutron Source (CSNS). Position-sensitive neutron detectors with a high counting rate and large area play an important role in the instruments performing neutron measurements in or close to the direct beam. The ceramic gas-electron-multiplier (GEM) detector serves as a promising solution, and considerable work has been done using the small-area GEM neutron detectors. In this article, we designed and constructed a detector prototype utilizing ceramic GEM foils with an effective area of about 307 mm$\times$307 mm. To evaluate and investigate their basic characteristics, the Monte Carlo (MC) tool FLUKA was employed and several neutron beam tests were conducted at CSNS. The simulated spatial resolution was basically in agreement with the measured value of 2.50$\pm$0.01 mm (FWHM). The wavelength spectra measurement was verified through comparisons with a commercial beam monitor. In addition, a detection efficiency of 4.7$\pm$0.1% was achieved for monoenergetic neutrons of 1.59 Å wavelength. This is consistent with the simulated result. The results indicate that the large-area ceramic GEM detector is a good candidate to implement neutron beam measurements. Its efficiency can be improved in a cascading manner to approach that reached by traditional $^{3}$He detectors.

Over the past few decades, angle-resolved photoemission spectroscopy (ARPES) has been one of the important tools to study electronic structure of crystals. In recent years, the spatial resolution of around 150 nm has been reached through tight focusing of the light spot (nano-ARPES). At present, the lower limit of the spot size of the light on the sample has been reached. Another way to further improve the spatial resolution is through using apertures to only let electrons from a small area of the sample pass. With both back-focal plane and image apertures, the size of the selected area can be as small as 20 nm. Yet, without aberration correction, the maximum opening angle at the sample for 20 nm spatial resolution is usually smaller than 3$^\circ$, making this method not suitable for nano-ARPES. As shown in this paper, a conventional aberration corrector, which corrects chromatic and third-order spherical aberrations, is not enough either. Only when the fifth-order spherical aberration is also corrected, the opening angle at the sample is large enough for nano-ARPES. In this paper, the design of a time-of-fight PEEM/ARPES/nano-ARPES instrument, which is currently under development at the Quantum Science Center of Guangdong-Hong Kong-Macao Greater Bay Area, is presented. The main point of innovation is a five-electrode electron mirror corrector, which is used to correct simultaneously chromatic, third-order and fifth-order spherical aberrations, resulting in 1 nm spatial resolution with $\sim 230$ mrad aperture angle in PEEM mode. This makes feasible the method of using apertures to improve the spatial resolution of the nano-ARPES mode. A new design of the magnetic prism array (MPA) is also presented, which preserves the rotational symmetry better than the existing designs.

With the rapid scaling of superconducting quantum processors, electronic control systems relying on commercial off-the-shelf instruments face critical bottlenecks in signal density, power consumption, and crosstalk mitigation. Here we present a custom dual-channel direct current (DC) source module (QPower) dedicated to large-scale superconducting quantum processors. The module delivers a voltage range of $\pm7$ V with 200 mA maximum current per channel, while achieving the following key performance benchmarks: noise spectral density of 20 nV/$\sqrt{\mathrm{Hz}}$ at 10 kHz, output ripple $<$500 μV$_{\mathrm{pp}}$ within 20 MHz bandwidth, and long-term voltage drift $<$5 μV$_{\mathrm{pp}}$ over 12 hours. Integrated into the control electronics of a 66-qubit quantum processor, QPower enables qubit coherence time of $T_1$ = 87.6 μs and Ramsey dephasing time of $T_2$ = 5.1 μs, with qubit resonance frequency drift constrained to $\pm40$ kHz during 12-hour operation. This modular design is compact in size and efficient in energy consumption, providing a scalable DC source solution for intermediate-scale quantum processors with stringent noise and stability requirements, with potential extensions to other quantum hardware platforms and precision measurement systems.

Combining optical tweezers with fluorescence microscopy is a powerful tool for single-cell analysis, playing a pivotal role in disease diagnosis, cell sorting, and the investigation of cellular dynamics. However, fluorescence detection faces challenges such as blinking, photobleaching and autofluorescence in biotissues. To address these limitations, we developed a magnetic detection strategy by integrating quantum magnetometry using nitrogen-vacancy centers into optical tweezers, demonstrating precise trapping and manipulation of individual cells in microfluidic environment. We detected a magnetic signal of 89 μT from a single cell labeled with magnetic nanoparticles, compared to a noise floor of 3.9 μT observed in unlabeled cells. This platform provides a promising approach for high-precision single-cell analysis and holds significant potential for probing cellular activities within biological microenvironments.

Pulsed magnet technology is the only way to generate ultra-strong magnetic fields higher than 45 T so far. However, the inherently fast-changing field strength (typically on the order of 1000 T/s) poses significant challenges for spectroscopic measurements which rely on time integration of signals to improve spectral qualities. In this work, we report high-sensitivity spectroscopic measurements under pulsed high magnetic fields employing the long flat-top pulsed magnetic field technique. By means of a multiple-capacitor power supply, we were able to generate pulsed high magnetic fields with controllable flat-top pulse width and field stabilities. By synchronizing spectroscopic measurements with the waveform of the flat-top magnetic field, the integration time of each spectrum can be increased by up to 100 times compared with that of the conventional spectroscopic measurements under pulsed magnetic fields, thus enabling high-sensitivity spectroscopic measurements under ultra-strong pulsed magnetic fields. These findings promise an efficient way to significantly improve the performance and extend the application of optical measurements under pulsed high magnetic fields.

Electrocaloric effect has attracted considerable attention for providing an eco-friendly and energy-efficient alternative to traditional vapor-compression refrigerators. In this review, we introduce theoretical explanations of positive and negative electrocaloric effects along with their measurements. In particular, we review recent advancements in prototypes of electrocaloric refrigeration and present their current advantages and shortcomings. Finally, we discuss the potential applications of the electrocaloric effect such as clothing and metamaterials to provide insights into future research.

Position-sensitive neutron detectors play an important role in neutron scattering studies. Detectors based on $^{6}$LiF/ZnS (Ag) scintillator and wave-shifting fiber have the advantages of high neutron detection efficiency, high position resolution, and large-area splicing, and can well meet the requirement of large area neutron detection for neutron diffractometers. An engineering detector prototype based on a $^{6}$LiF/ZnS (Ag) scintillation screen and SiPM array readout was fabricated for the General Purpose Powder Diffractometer of China Spallation Neutron Source (CSNS). The detector has an active area of 196 $\rm mm \times 444$ mm, with a pixel size of 4 $\rm mm \times 4 $ mm. The key performances of the detector prototype were tested at the BL20 neutron beam line of CSNS. The test results show that the neutron detection efficiency of the detector was 32% and 42% at wavelengths of 1.4 Å and 2.8 Å, respectively. An interpolated neutron detection efficiency of 40.2% at a wavelength of 2 Å was obtained. The tested neutron efficiency non-uniformity of the detector was 10.2%, which is less than one-half that of the current general purpose powder diffractometer scintillator neutron detectors at CSNS. This work achieves, for the first time, an efficiency uniformity of $< 11%$ in large-area mosaic neutron detectors, alongside significant advancements in electromagnetic interference immunity and cost-effectiveness.

Accurate thrust assessment is crucial for characterizing the performance of micro-thrusters. This paper presents a comprehensive evaluation of the thrust generated by a needle-type indium field emission electric propulsion (In-FEEP) micro-thruster using three methods based on a pendulum: direct thrust measurement, indirect plume momentum transfer and beam current diagnostics. The experimental setup utilized capacitive displacement sensors for force detection and a voice coil motor as a feedback actuator, achieving a resolution better than 0.1 μN. Key performance factors such as ionization and plume divergence of ejected charged particles were also examined. The study reveals that the high applied voltage induces significant electrostatic interference, becoming the dominant source of error in direct thrust measurements. Beam current diagnostics and indirect plume momentum measurements were conducted simultaneously, showing strong agreement within a deviation of less than 0.2 μN across the operational thrust range. The results from all three methods are consistent within the error margins, verifying the reliability of the indirect measurement approach and the theoretical thrust model based on the electrical parameters of In-FEEP.

Traceability is the fundamental premise of all metrological activities. The establishment of a traceability chain characterized by a shortened structure, while simultaneously enabling on-site traceability, represents a key trend in the advancement of metrology. This study explores the periodic accuracy and overall uniformity of self-traceable gratings, employing multilayer film gratings with a nominal period of 25.00 nm as the medium. We present a comparative analysis of measurement capabilities in a self-traceable grating calibration system characterized by a 'top-down' calibration approach and a Si lattice constant calibration system characterized by a 'bottom-up' calibration approach. The results indicate that the values obtained for the multilayer film grating periods, calibrated using the self-traceable grating system, are 24.40 nm with a standard deviation of 0.11 nm. By comparing with the values derived from the Si lattice constant, which yield 24.34 nm with a standard deviation of 0.14 nm, the validity and feasibility of the self-traceable calibration system are confirmed. This system extends and complements existing metrological frameworks, offering a precise pathway for traceability in precision engineering and nanotechnology research.

The spherical crystal imaging system, noted for its high energy spectral resolution (monochromaticity) and spatial resolution, is extensively applied in high energy density physics and inertial confinement fusion research. This system supports studies on fast electron transport, hydrodynamic instabilities, and implosion dynamics. The x-ray source, produced through laser-plasma interaction, emits a limited number of photons within short time scales, resulting in predominantly photon-starved images. Through ray-tracing simulations, we investigated the impact of varying crystal dimensions on the performance of a spherical crystal self-emission imager. We observed that increasing the crystal dimension leads to higher imaging efficiency but at the expense of monochromaticity, causing broader spectral acceptance and reduced spatial resolution. Furthermore, we presented a theoretical model to estimate the spatial resolution of the imaging system within a specific energy spectrum range, detailing the expressions for the effective size of the crystal. The spatial resolution derived from the model closely matches the numerical simulations.

We develop a quantum precision measurement method for magnetic field at the Tesla level by utilizing a fiber diamond magnetometer. Central to our system is a micron-sized fiber diamond probe positioned on the surface of a coplanar waveguide made of nonmagnetic materials. Calibrated with a nuclear magnetic resonance magnetometer, this probe demonstrates a broad magnetic field range from 10 mT to 1.5 T with a nonlinear error better than 0.0028% under a standard magnetic field generator and stability better than 0.0012% at a 1.5 T magnetic field. Finally, we demonstrate quantitative mapping of the vector magnetic field on the surface of a permanent magnet using the diamond magnetometer.

We outline an experimental setup for efficiently preparing a tweezer array of $^{88}$Sr atoms. Our setup uses permanent magnets to maintain a steady-state two-dimensional magneto-optical trap (MOT) which results in a loading rate of up to $10^{8}$ s$^{-1}$ at 5 mK for the three-dimensional blue MOT. This enables us to trap $2\times10^{6}$ $^{88}$Sr atoms at 2 μK in a narrow-line red MOT with the $^{1}$S$_{0}$ $\rightarrow$ $^{3}$P$_{1}$ intercombination transition at 689 nm. With the Sisyphus cooling and pairwise loss processes, single atoms are trapped and imaged in 813 nm optical tweezers, exhibiting a lifetime of 2.5 min. We further investigate the survival fraction of a single atom in the tweezers and characterize the optical tweezer array using a release and recapture technique. Our experimental setup serves as an excellent reference for those engaged in experiments involving optical tweezer arrays, cold atom systems, and similar research.

The Chinese Academy of Engineering Physics Terahertz Free Electron Laser Facility (CAEP THz FEL, CTFEL) is the only high-average power free electron laser terahertz source based on superconducting accelerators in China. The update of the CTFEL is now undergoing and will expand the frequency range from 0.1-4.2 THz to 0.1-125 THz. Two experimental stations for material spectroscopy and biomedicine will be built. A high harmonic generation (HHG) lightsource based beamline at the material spectroscopy experimental station for time-resolved angle-resolved photoemission spectroscopy (ARPES) research will be constructed and the optical design is presented. The HHG lightsource covers the extreme ultraviolet (XUV) photon energy range of 20-50 eV. A Czerny-Turner monochromator with two plane gratings worked in conical diffraction configuration is employed to maintain the transmission efficiency and preserve the pulse time duration. The calculated beamline transmission efficiency is better than 5% in the whole photon energy range. To our knowledge, this is the first time in China to combine THz-infrared FEL with HHG light source, and this experimental station will be a powerful and effective instrument that will give new research opportunities in the future for users doing research on the dynamic evolution of the excited electron band structure of a material's surface.

Laser absorption spectroscopy has proven to be an effective approach for gas sensing, which plays an important role in the fields of military, industry, medicine and basic research. This paper presents a multiplexed gas sensing system based on optical frequency comb (OFC) calibrated frequency-modulated continuous-wave (FMCW) tuning nonlinearity. The system can be used for multi-parameter synchronous measurement of gas absorption spectrum and multiplexed optical path. Multi-channel parallel detection is realized by combining wavelength division multiplexing (WDM) and frequency division multiplexing (FDM) techniques. By introducing nonlinear optical crystals, broadband spectrum detection is simultaneously achieved over a bandwidth of hundreds of nanometers. An OFC with ultra-high frequency stability is used as the frequency calibration source, which guarantees the measurement accuracy. The test samples involve H$^{13}$C$^{14}$N, C$_{2}$H$_{2}$ and Rb vapor cells of varying densities and 5 parallel measurement experiments are designed. The results show that the measurement accuracies of spectral absorption line and the optical path are 150 MHz and 20 μm, respectively. The scheme offers the advantages of multiplexed, multi-parameter, wide spectrum and high resolution detection, which can realize the identification of multi-gas components and the high-precision inversion of absorption lines under different environments. The proposed sensor demonstrates great potential in the field of high-resolution absorption spectrum measurement for gas sensing applications.

This article proposes a new physics package to enhance the frequency stability of the space cold atom clock with the advantages of a microgravity environment. Clock working processes, including atom cooling, atomic state preparation, microwave interrogation, and transition probability detection, are integrated into the cylindrical microwave cavity to achieve a high-performance and compact physics package for the space cold atom clock. We present the detailed design and ground-test results of the cold atom clock physics package in this article, which demonstrates a frequency stability of $1.2 \times 10^{-12}$ $\tau^{-1/2}$ with a Ramsey linewidth of 12.5 Hz, and a better performance is predicted with a 1 Hz or a narrower Ramsey linewidth in microgravity environment. The miniaturized cold atom clock based on intracavity cooling has great potential for achieving space high-precision time-frequency reference in the future.

We have successfully developed cryogen-free dilution refrigerators with medium cooling power that can be applied to quantum experiments. Breakthroughs have been made in some key technologies and components of heat switches and dilution units. Our prototype has been running continuously and stably for more than 100 hours below 10 mK, with a minimum temperature of 7.6 mK and a cooling power of 450 μW at 100 mK. At the same time, we have also made progress in the application of dilution refrigerators, such as quantum computing, low-temperature detector, and magnet integration. These indicators and test results indicate good prospects for application in physics, astronomy, and quantum information.

Based on previously reported work, we propose a new method for calibrating image plate (IP) scanners, offering greater flexibility and convenience, which can be extended to the calibration tasks of various scanner models. This method was applied to calibrate the sensitivity of a GE Typhoon FLA 7000 scanner. Additionally, we performed a calibration of the spontaneous signal attenuation behavior for BAS-MS, BAS-SR, and BAS-TR type IPs under the 20$\pm$1$^\circ$C environmental conditions, and observed significant signal carrier diffusion behavior in BAS-MS IP. The calibration results lay a foundation for further research on the interaction between ultra-short, ultra-intense lasers and matter.

Atom tracking technology enhanced with innovative algorithms has been implemented in this study, utilizing a comprehensive suite of controllers and software independently developed domestically. Leveraging an on-board field-programmable gate array (FPGA) with a core frequency of 100 MHz, our system facilitates reading and writing operations across 16 channels, performing discrete incremental proportional-integral-derivative (PID) calculations within 3.4 microseconds. Building upon this foundation, gradient and extremum algorithms are further integrated, incorporating circular and spiral scanning modes with a horizontal movement accuracy of 0.38 pm. This integration enhances the real-time performance and significantly increases the accuracy of atom tracking. Atom tracking achieves an equivalent precision of at least 142 pm on a highly oriented pyrolytic graphite (HOPG) surface under room temperature atmospheric conditions. Through applying computer vision and image processing algorithms, atom tracking can be used when scanning a large area. The techniques primarily consist of two algorithms: the region of interest (ROI)-based feature matching algorithm, which achieves 97.92% accuracy, and the feature description-based matching algorithm, with an impressive 99.99% accuracy. Both implementation approaches have been tested for scanner drift measurements, and these technologies are scalable and applicable in various domains of scanning probe microscopy with broad application prospects in the field of nanoengineering.

The haloscope based on the $\rm TM_{010}$ mode cavity is a well-established technique for detecting QCD axions. However, the method has limitations in detecting high-mass axion due to significant volume loss in the high-frequency cavity. Utilizing a higher-order mode cavity can effectively reduce the volume loss of the high-frequency cavity. The rotatable dielectric pieces as a tuning mechanism can compensate for the degradation of the form factor of the higher-order mode. Nevertheless, the introduction of dielectric causes additional volume loss. To address these issues, this paper proposes a novel design scheme by adding a central metal rod to the higher-order mode cavity tuned by dielectrics, which improves the performance of the haloscope due to the increased effective volume of the cavity detector. The superiority of the novel design is demonstrated by comparing its simulated performance with previous designs. Moreover, the feasibility of the scheme is verified by the full-wave simulation results of the mechanical design model.