Table of Content

15 November 2023, Volume 43 Issue 5

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Review of Research Advance on Cold-atom Gravimeter

BAI Jin-hai, MA Hui-juan, HU Dong, WANG Yu

2023, 43(5):  1-10.  doi:10.12060/j.issn.1000-7202.2023.05.01

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The cold atom gravimeter uses laser cooling,atomic interference manipulation,and other technologies to achieve absolute gravity acceleration measurement.It is a new type of quantum sensor that has developed rapidly over the [JP2]past three decades.Currently,its measurement sensitivity has exceeded that of traditional laser interference absolute gravimeters,and the measurement uncertainty has reached the same level.In metrology traceability,basic scientific research,geophysics,resource exploration,autonomous navigation and other aspects have important application value.Analyzes the principle of cold atom gravimeters,introduces the research progress and development trend of cold atom gravimeters,and analyzes and combs the research direction of cold atom gravimeters,especially the key points in dynamic application scenarios.

Development Trend of Metrology and Measurement in the Quantization and Digitalization Revolution

DU Xiao-shuang, HU Yi-fei, FENG Ying-qiang, CHEN Bei, ZENG Wu, FEI Feng, LI Wei, TU Zhi-guo, YANG Xiao-wei, ZHAI Yu-wei, HAO Xin-you

2023, 43(5):  11-22.  doi:10.12060/j.issn.1000-7202.2023.05.02

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Developed countries in the America and Europe attach great importance to the development of metrology and measurement technology,incorporating forward-looking and fundamental measurement technologies such as quantum and digital intelligence into their national development strategies,and seizing the technological high ground.In recent years,China has made breakthroughs in metrology research fields such as atomic frequency standards and cold atomic gravimeters,and has entered the ranks of advanced countries in international metrology.At present,with the quantization and digital transformation of international metrology,the evolution of quantization in metrology is constantly accelerating,the mode of measurement transmission is gradually transitioning towards digitization,and the trend of metrology support technology is becoming more practical.The development trend of metrology and measurement technology is given and a close analysis is made in this paper,providing a useful reference for the development of China metrology and measurement.

Development Trend of High Performance Passive CPT Atomic Clock 

DING Chen-feng, CHEN Hai-jun

2023, 43(5):  23-30.  doi:10.12060/j.issn.1000-7202.2023.05.03

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The use of a single circularly polarized light configuration to achieve a CPT state will generate a polarized dark state,resulting in a lower contrast of the CPT signal.Therefore,the frequency stability index of traditional CPT atomic clocks is not high.In order to improve the contrast of CPT signals and improve the performance of CPT atomic clocks,various schemes for eliminating polarized dark states have been proposed and studied.These schemes can be divided into parallel line polarized light configurations and phase delayed configurations based on the polarization state and generation method of the laser used σ⁺-σ^- Configuration,push-pull pump configuration,vertically polarized light configuration,polarization modulation configuration.Based on the principles and development level of these schemes,a comparative analysis of their advantages,disadvantages,and improvement plans can be conducted to explore new development directions for high-performance atomic clocks under different demand conditions.

Research Progress on the Mercury Ion Trapped Microwave Clock

WANG Nuan-rang, YI Hang, XUE Xiao-bo, ZHANG Sheng-kang

2023, 43(5):  31-35.  doi:10.12060/j.issn.1000-7202.2023.05.04

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The mercury ion trapped microwave clock utilizes a quadrupole trap to achieve ion trapping,and completes the preparation of mercury ion states through a mercury lamp,making it easy to integrate and miniaturize.Through the optimization and design of key components such as ion trap,mercury lamp and its optical path,the pump light emitted by the mercury lamp can fully interact with the ions trapped in the ion trap to complete the preparation of states.40.5 GHz microwave is transmitted to the center of the ion trap through the horn antenna to complete the inversion of the ion number.The transiting line of the trapped mercury ions is detected by a weak fluorescence detection system and the measured transiting line width is about 1 Hz.The closed-loop locking of mercury ion microwave clock is achieved by the servo loop control system.After experiment testing,the frequency stability index can reach 4E-13/τ(1 s≤τ≤1 000 s) and 7E-15 at 10 000 s.

Development Status of Weak Current Metrology Calibration Technique Based on Atomic Magnetic Field Detection

LI Wei-peng, WEI Xiao-gang, YANG Ren-fu

2023, 43(5):  36-40.  doi:10.12060/j.issn.1000-7202.2023.05.05

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With the rapid improvement in the sensitivity of atomic magnetometers,the application of magnetic field measurement methods based on atomic ensemble is gradually expanding.In recent years,several studies have been conducted on the use of atomic magnetometers for weak current measurements,and the results have revealed the potential of this measurement method for enhancing current stability.With the high sensitivity characteristics of an atomic magnetometer,weak changes in the current are monitored by the magnetic field generated by the current,and the current is stabilized using feedback from the magnetic field measurements.It mainly describes the basic principle of atomic magnetic field detection and the current status of its application in the field of current measurement,and analyzes the key influencing factors of current measurement using atomic magnetometers,and looks forward to the development trend of this technology.

Development Status and Metrology Prospect of Terahertz Quantum Correlation Imaging and Quantum Dot Detector

LI Hong-guang, WANG Yuan-bo, LIAO Wen-tao

2023, 43(5):  41-46.  doi:10.12060/j.issn.1000-7202.2023.05.06

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The cross research between quantum technology and cutting-edge disciplines such as terahertz technology has led to the emergence of disruptive new system devices such as terahertz quantum correlation cameras and quantum dot detectors,expanding the space for new quality and new domain defense applications.Compared to traditional imaging technology,terahertz quantum correlation imaging based on quantum technology exhibits unique advantages in imaging speed,imaging resolution,and other aspects.The terahertz quantum correlation imaging system is based on terahertz emission sources,detection systems,masks,algorithms,etc.,achieving compression sensing,time resolution,Fourier transform,and other imaging technologies.In addition,a review was conducted on terahertz quantum correlation imaging systems and quantum dot detectors,and corresponding research on terahertz quantum correlation imaging and measurement calibration technology of terahertz quantum dot detectors was explored.By proposing metrological problems and solutions,which provides the application prospects of terahertz quantum detection and imaging metrology technology.

Research Progress on Graphene Sensor and Quantum Dots

DONG Jun-wei, LU Yi, LIU Xia, GUO Guo-jian, YOU Xin-ran, WANG Wei, TAO Wei, WANG Ze-xi

2023, 43(5):  47-51.  doi:10.12060/j.issn.1000-7202.2023.05.07

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As a new type of two-dimensional material in the 21st century,graphene has very few lattice defects and has the characteristics of zero band gap.Based on the unique electrical performance of graphene,it has extremely high sensitivity in the field of sensing.By controlling the physical size of the graphene,the obtained graphene quantum dot(GQDS) has the advantages of optical lighting,low toxicity,and luminous adjustment,and plays an important role in fluorescent imaging,drug treatment,and biosensing.Based on the excellent characteristics of graphene as a sensor and quantum dot,some applications of graphene in the quantum field are summarized,and the future development direction of graphene is outlook.

Noise Suppression of Laser-pumped Cesium-Helium Optical Magnetometer

FU Ji-qing, KONG Jia, CHENG Hua-fu

2023, 43(5):  52-56.  doi:10.12060/j.issn.1000-7202.2023.05.08

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This paper describes a laser-pumped cesium-helium magnetometer(CHM).By using the single mode diode laser to get higher polarization efficiency,the stronger magnetic-resonance signal compared with the conventional lamp-pumped scheme is got.By measuring the noises from light,background field,pulse discharge and signal amplifier circuits,we find that the light power fluctuation is the dominant noise.We study the relation between signal-to-noise ratio and the light intensity,and then find out an optimal light intensity.Under the best experimental parameters,the peak-to-peak noise can superior to 0.02 nT.The results of the experiment show that by improving the stability of the light power,the laser pumped CHM has great potential to achieve a higher accuracy than proton magnetometers,can be used as a new generation of main measuring equipment for constant weak magnetic field measurement.

Research on Quantum Efficiency Calibration Technique for Single Photon Detector Based on Correlated photon Pairs

ZHANG Peng-ju, ZHUANG Xin-gang, LIU Chang-ming, LIU Hong-bo, SHI Xue-shun, SHEN Rong-ren, LIN Yong-jie

2023, 43(5):  57-62.  doi:10.12060/j.issn.1000-7202.2023.05.09

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With the development of quantum technology,the research direction of extremely weak light radiation is gradually developing towards quantization.The main focus is on the measurement of the relevant parameters of the single photon detector based on the correlated photon pairs method.The principle of using conformal measurement and the design method of nonlinear crystals in correlated photon sources are introduced.A laser with wavelength of 355 nm is used as the pump light source.It pumps the BBO crystals with phase matching angle of 36° for the correlated photon pairs output from 450 nm to 1 675 nm.It pumps the BBO crystals with phase matching angles of 28.1°,32.91°,and 31.29° for the correlated photon common line output at 460 nm and 1 550 nm,632.8 nm and 807 nm,1064 nm and 532 nm.The quantum efficiency of the single-photon detector is measured at 460 nm,1550 nm,632.8 nm,and 1064 nm wavelength points using conformal measurements,laying the foundation for realizing multi-wavelength point to full-band single-photon detector testing.

Software Design of Hydrogen Atomic Clock Frequency Steering System Based on Optical Frequency Standards

XU Jin-feng, SHI Feng-feng, LI Guo-jun, LIN Yong-xin

2023, 43(5):  63-67.  doi:10.12060/j.issn.1000-7202.2023.05.10

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The time system of combining optical frequency standards and hydrogen atomic clocks requires integration of instrument control,data acquisition,atomic clock performance evaluation,and other functions to address the impact of low effective operation rate of optical frequency standards on the frequency steering of hydrogen atomic clocks.Therefore,a hydrogen atomic clock frequency steering system software has been designed.The software uses interchangeable virtual instrument drivers and network communication to achieve data interaction between devices.The data preprocessing strategy using the Median Absolute Deviation(MAD）method is used to detect outliers in measurement data,and the core program is written using the Alglib numerical analysis and data mining function library.Experiments have shown that the synchronization accuracy between the time signal generated by the hydrogen atomic clock and UTC is less than 2.5 ns under the condition of an effective operating rate of 80% for the optical frequency standard.

Intercomparison of Environmental Nuclear Radiation Measuring

GAO Fei, WANG Jing-qian, DONG Lu-qi, WANG Fei-fei

2023, 43(5):  68-74.  doi:10.12060/j.issn.1000-7202.2023.05.11

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In order to check and promote the improvement of calibration ability and the technical ability of operators,and ensure the reliability of monitoring data,the measurement and comparison work of environmental nuclear radiation monitoring instrument was carried out.The intercomparison includes environmental level dosemeters, protection level dosemeters which coverage for environmental level,and γ-ray air kerma secondary standard ionization chamber.The intercomparison parameters involve air kerma and ambient dose equivalent.The intercomparison covers a wide range of environmental nuclear radiation monitoring instruments.X-ray response,γ-rays and cosmic rays response properties of the environmental nuclear radiation monitoring instruments were studied.The E_n value and relative error were compared to analyze and evaluate the results.As the intercomparison results,the E_n values of standard ionization chambers in calibration laboratory are less than 1,and all meet requirements.Most of the environmental radiation monitoring instruments meet the requirements of S-Cs measurement.However,the X-ray response of most monitoring instruments are poor.Some monitoring instrument cannot meet the requirements that the energy response variation limit dose not exceed ±30%,so it is recommended that the instrument user should verify its energy response during the first inspection.

An Improved Modeling Algorithm for Indoor Ray Tracing Based on a Ten-ray Model

ZHANG Zi-yue, YAN Tian-feng, GAO Rui, XIAO Lin-hu, NIU Rui-ting

2023, 43(5):  75-81.  doi:10.12060/j.issn.1000-7202.2023.05.12

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With the rapid development of mobile communication technology and the Internet of Things,predicting the signal coverage of short-range wireless communication networks indoors has become a current research hotspot.An improved ray-tracing modeling algorithm was developed independently based on the ten-ray model.This model method provides visualized scene simulation for microwave indoor propagation,realizing the prediction of short-range indoor radio wave propagation and visualization of electromagnetic field strength.Tested in a variety of scenarios and compared with other indoor airwave transmission models,the results show that the root mean square error of the calibrated model is reduced to 5.53,which is more accurate and can more accurately predict the received signal power in indoor environments.

Throughput Optimization Strategy for Unmanned Aerial Vehicles Assistance-Cognitive Radio Networks

SUN Shi-bing, MA Pei-xun

2023, 43(5):  82-87.  doi:10.12060/j.issn.1000-7202.2023.05.13

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Using the Unmanned Aerial Vehicle(UAV) as a mobile base station in the air can effectively increase the amount of transmitted data and improve the coverage of users.Therefore,for throughput optimization of Cognitive Radio Network(CRN) assisted by UAV,a strategy to maximize the throughput of primary and secondary network regions based on UAV power allocation and numbers of UAV is proposed in this paper.Firstly,the throughput objective function of the primary and secondary network regions is established.And the objective function is dealt with by non-convex.The logarithm inequality is used to solve the objective function.Finally,the optimal power of UAV and numbers of UAV are obtained.The performance analysis shows that the proposed throughput optimization strategy can maximize the network throughput.

Received Signal Strength Index-based Secure RPL

XU Hui-bin, LU Yu-chang, WANG Yu-ting

2023, 43(5):  88-93.  doi:10.12060/j.issn.1000-7202.2023.05.14

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Routing Protocol for low power and Lossy network(RPL) is a popular protocol used in wireless Internet of Things(IoT) network.However,RPL routing is vulnerable to sybil attacks because it does not adopt a centralized security mechanism.Therefore,RPL routing against sybil attack by received signal strength index-based(RSPL) is proposed in this paper.In RSPL,the reliability of nodes is estimated through the statistics of RSSI,and the attack is detected by neighbor node through their observation.In addition,objective function in RPL is modified by Expected Transmission Count(ETX) and trust of link in order to protect the attack node from participating in the route.Simulation results show that RSPL improves the detection ratio of sybil node and packet delivery ratio compared with other schemes.

Performance Analysis of UAV Relaying Emergency Communication Network Based on Intelligent Reflection Surface

MA Pei-xun

2023, 43(5):  94-100.  doi:10.12060/j.issn.1000-7202.2023.05.15

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In the area where the cellular base station cannot provide communication coverage for ground users,the Unmanned Aerial Vehicle(UAV）can be used as relay to construct UAV-emergency communication system.In order to improve the spectral efficiency and reduce the outage probability,emergency communication architecture based on Intelligent Reflecting Surface(IRS）assisted UAV relaying is proposed in this paper.In the communication architecture,cellular base station employs non orthogonal multiple access(NOMA）to serve ground users.An IRS is mounted on UAV.IRS reflects the signal transmitted from the base station to the ground users to overcome the non-line-of-sight link environment between the base station and the users,so that the outage probability is reduced.At the same time,the outage probability of communication is derived,and a bound of the ergodic spectral efficiency is estimated.Numerical results were given to confirm the validity of our theoretical analysis and the superiority of the proposed communication architecture.