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Magnetic-field-sensitive multi-wave interference

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Frontiers of physics 2023年第5期18卷 201-207页

作者： Wenhua Yan Xudong Ren Wenjie Xu Zhongkun Hu Minkang Zhou moe key laboratory of fundamental physical quantities measurements Hubei Key Laboratory of Gravitation and Quantum PhysicsPGMF and School of PhysicsHuazhong University of Science and TechnologyWuhan 430074China Wuhan Institute of quantum Technology Wuhan 430206China

We report an experimental study of magnetic-field-sensitive multi-wave interference,realized in a three-wave RF-atom system.In the F=1 hyperfine level of the ^(87)Rb 5^(2)S_(1/2) ground state,Ramsey fringes were observed via the spin-selective Raman detection.A decrease in the fringe contrast was observed with increasing free evolution time.The maximum evolution time for observable fringe contrasts was investigated at different atom temperatures,under free-falling and trapped conditions.As the main interest of the Ramsey method,the improvement in magnetic field resolution is observed with an increase of evolution time T up to 3 ms and with the measurement resolution reaching 0.85 nT.This study paves the way for precision magnetic field measurements based on cold atoms.

关键词： atom interferometer magnetometer cold atom device multi-wave interference

Mode-localized accelerometer in the nonlinear Duffing regime with 75 ng bias instability and 95 ng/√Hz noise floor

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Microsystems & Nanoengineering 2022年第1期8卷 237-247页

作者： Hemin Zhang Milind Pandit Guillermo Sobreviela Madan Parajuli Dongyang Chen Jiangkun Sun Chun Zhao Ashwin A.Seshia The Nanoscience Centre University of CambridgeCambridge CB30FFUK Silicon Microgravity Ltd. Cambridge Innovation ParkCambridge CB259PBUK moe key laboratory of fundamental physical quantities measurement and hubei key laboratory of gravitation and quantum physics PGMF and School of PhysicsHuazhong University of Science and Technology430074 WuhanChina

Mode-localized sensors have attracted attention because of their high parametric sensitivity and first-order common-mode rejection to temperature drift.The high-fidelity detection of resonator amplitude is critical to determining the resolution of mode-localized sensors where the measured amplitude ratio in a system of coupled resonators represents the output metric.Operation at specific bifurcation points in a nonlinear regime can potentially improve the amplitude bias stability;however,the amplitude ratio scale factor to the input measurand in a nonlinear regime has not been fully investigated.This paper theoretically and experimentally elucidates the operation of mode-localized sensors with respect to stiffness perturbations(or an external acceleration field)in a nonlinear Duffing regime.The operation of a mode-localized accelerometer is optimized with the benefit of the insights gained from theoretical analysis with operation in the nonlinear regime close to the top critical bifurcation point.The phase portraits of the amplitudes of the two resonators under different drive forces are recorded to support the experimentally observed improvements for velocity random walk.Employing temperature control to suppress the phase and amplitude variations induced by the temperature drift,1/f noise at the operation frequency is significantly reduced.A prototype accelerometer device demonstrates a noise floor of 95 ng/√Hz and a bias instability of 75 ng,establishing a new benchmark for accelerometers employing vibration mode localization as a sensing paradigm.A mode-localized accelerometer is first employed to record microseismic noise in a university laboratory environment.

关键词： nonlinear bifurcation gained

Energy in critical collapse

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Communications in Theoretical physics 2023年第12期75卷 97-104页

作者： Yu Hu Jun-Qi Guo Junbin Li Cheng-Gang Shao Hongsheng Zhang moe key laboratory of fundamental physical quantities measurement Hubei Key Laboratory of Gravitation and Quantum PhysicsPGMFand School of PhysicsHuazhong University of Science and TechnologyWuhan 430074HubeiChina School of physics and Technology University of JinanJinan 250022ShandongChina Department of Mathematics Sun Yat-sen UniversityGuangzhou 510275GuangdongChina

We study the energy issue in critical collapse.It is found that in critical collapse,the contribution from the material energy is greater than that from the gravitational energy.The quantity m/r plays an important role in identifying the formation of an apparent horizon in gravitational collapse,where m is the Misner-Sharp mass and r is the areal radius.We observe that in critical collapse,the maximum value of m/r fluctuates between 2/15 and 4/15.This denotes a large gap between critical collapse and black hole formation for which the criterion is m/r=1/2.

关键词： quasi-local energy critical collapse numerical relativity

A multi-band atomic candle with microwave-dressed Rydberg atoms

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Frontiers of physics 2023年第1期18卷 201-207页

作者： Yafen Cai Shuai Shi Yijia Zhou Jianhao Yu Yali Tian Yitong Li Kuan Zhang Chenhao Du Weibin Li Lin Li moe key laboratory of fundamental physical quantities measurement Hubei Key Laboratory of Gravitation and Quantum PhysicsPGMFInstitute for Quantum Science and EngineeringSchool of PhysicsHuazhong University of Science and TechnologyWuhan 430074China Graduate School of China Academy of Engineering physics Beijing 100193China School of physics and Astronomy and Centre for the Mathematics and Theoretical physics of quantum Non-equilibrium Systems University of NottinghamNottinghamNG72RDUK

Stabilizing important physical quantities to atom-based standards lies at the heart of modern atomic,molecular and optical physics,and is widely applied to the field of precision metrology.Of particular importance is the atom-based microwave field amplitude stabilizer,the so-called atomic candle.Previous atomic candles are realized with atoms in their ground state,and hence suffer from the lack of frequency band tunability and small stabilization bandwidth,severely limiting their development and potential applications.To tackle these limitations,we employ microwave-dressed Rydberg atoms to realize a novel atomic candle that features multi-band frequency tunability and large stabilization bandwidth.We demonstrate amplitude stabilization of microwave field from C-band to Ka-band,which could be extended to quasi-DC and terahertz fields by exploring abundant Rydberg levels.Our atomic candle achieves stabilization bandwidth of 100 Hz,outperforming previous ones by more than two orders of magnitude.Our simulation indicates the stabilization bandwidth can be further increased up to 100 kHz.Our work paves a route to develop novel electric field control and applications with a noise-resilient,miniaturized,sensitive and broadband atomic candle.

关键词： Rydberg atoms microwave atomic spectroscopy

A 532 nm molecular iodine optical frequency standard based on modulation transfer spectroscopy

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Chinese physics B 2021年第5期30卷 277-286页

作者：程飞虎金宁张风雷李慧杜远博张洁邓科陆泽晃 moe key laboratory of fundamental physical quantities measurement Hubei Key Laboratory of Gravitation and Quantum PhysicsPGMF and School of PhysicsHuazhong University of Science and TechnologyWuhan 430074China

We report construction of an iodine-stabilized laser frequency standard at 532 nm based on modulation transfer spectroscopy(MTS)technology with good reproducibility.A frequency stability of 2.5×10^(-14)at 1 s averaging time is achieved,and the frequency reproducibility has a relative uncertainty of 3.5×10^(-13),demonstrating the great stability of our setup.The systematic uncertainty of the iodine-stabilized laser frequency standard is evaluated,especially the contribution of the residual amplitude modulation(RAM).The contribution of the RAM in MTS cannot be evaluated directly.To solve this problem,we theoretically deduce the MTS signal with RAM under large modulation depth,and prove that the non-symmetric shape of the MTS signal is directly related to the MTS effect.The non-symmetric shape factor can be calibrated with a frequency comb,and in real experiments,this value can be obtained by least-squares fitting of the MTS signal,from which we can infer the RAMinduced frequency shift.The full frequency uncertainty is evaluated to be 5.3 kHz(corresponding to a relative frequency uncertainty of 9.4×10^(-12)).The corrected transition frequency has a difference from the BIPM-recommended value of 2 kHz,which is within 1σ uncertainty,proving the validity of our evaluation.

关键词： iodine-stabilized laser frequency standard modulation transfer spectroscopy residual amplitude modulation

Movable precision gravimeters based on cold atom interferometry

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Chinese physics B 2020年第9期29卷 70-78页

作者：张炯阳陈乐乐程源罗覃舒玉彪段小春周敏康胡忠坤 moe key laboratory of fundamental physical quantities measurement&hubei key laboratory of gravitation and quantum physics PGMF and School of PhysicsHuazhong University of Science and TechnologyWuhan 430074China

High precision atom interferometers have shown attractive prospects in laboratory for testing fundamental physics and inertial sensing.Efforts on applying this innovative technology to field applications are also being made intensively.As the manipulation of cold atoms and related matching technologies mature,inertial sensors based on atom interferometry can be adapted to various indoor or mobile platforms.A series of experiments have been conducted and high performance has been achieved.In this paper,we will introduce the principles,the key technologies,and the applications of atom interferometers,and mainly review the recent progress of movable atom gravimeters.

关键词： atom interferometer absolute gravimeter precision measurement

Testing the Universality of Free Fall by Comparing the Atoms in Different Hyperfine States with Bragg Diffraction

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Chinese physics Letters 2020年第4期37卷 36-40页

作者：张柯周敏康程源陈乐乐罗覃徐文杰曹鲁帅段小春胡忠坤 moe key laboratory of fundamental physical quantities measurement&hubei key laboratory of gravitation and quantum physics PGMF and School of PhysicsHuazhong University of Science and TechnologyWuhan 430074

We perform a precision atom interferometry experiment to test the universality of free fall.Our experiment employs the Bragg atom interferometer with 87Rb atoms either in hyperfine state|F=1,mF=0>or|F=2,mF=0>,and the wave packets in these two states are diffracted by one pair of Bragg beams alternatively,which is helpful for suppressing common-mode systematic errors.We obtain an Eotvos ratioη1-2=(0.9±2.7)×10^-10,and set a new record on the precision with improvement of nearly 5 times.This measurement also provides constraint on the difference of the diagonal terms of the mass-energy operator.

关键词： diagonal constraint interferometry

Precision measurement of the Newtonian gravitational constant

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National Science Review 2020年第12期7卷 1803-1817页

作者： Chao Xue Jian-Ping Liu Qing Li Jun-Fei Wu Shan-Qing Yang Qi Liu Cheng-Gang Shao Liang-Cheng Tu Zhong-Kun Hu Jun Luo Tian Qin Research Center for gravitational physics & School of physics and Astronomy Sun Yat-sen University(Zhuhai Campus) moe key laboratory of fundamental physical quantities measurement & hubei key laboratory of gravitation and quantum physics PGMF and School of PhysicsHuazhong University of Science and Technology

The Newtonian gravitational constant G,which is one of the most important fundamental physical constants in nature,plays a significant role in the fields of theoretical physics,geophysics,astrophysics and astronomy.Although G was the first physical constant to be introduced in the history of science,it is considered to be one of the most difficult to measure accurately so far.Over the past two decades,eleven precision measurements of the gravitational constant have been performed,and the latest recommended value for G published by the Committee on Data for Science and Technology(CODATA) is(6.674 08 ±0.000 31) × 10m~3 kgswith a relative uncertainty of 47 parts per million.This uncertainty is the smallest compared with previous CODATA recommended values of G;however,it remains a relatively large uncertainty among other fundamental physical constants.In this paper we briefly review the history of the G measurement,and introduce eleven values of G adopted in CODATA 2014 after 2000 and our latest two values published in 2018 using two independent methods.

关键词： precision measurement Newtonian gravitational constant CODATA

Parameter estimation for Einstein-dilaton-Gauss-Bonnet gravity with ringdown signals

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Chinese physics C 2023年第10期47卷 213-224页

作者：邵才莹胡宇邵成刚 moe key laboratory of fundamental physical quantities measurement Hubei Key Laboratory of Gravitation and Quantum PhysicsPGMFand School of PhysicsHuazhong University of Science and TechnologyWuhan 430074China

Future space-based gravitational-wave detectors will detect gravitational waves with high sensitivity in the millihertz frequency band,providing more opportunities to test theories of gravity than ground-based detectors.The study of quasinormal modes(QNMs)and their application in gravity theory testing have been an important aspect in the field of gravitational physics.In this study,we investigate the capability of future space-based gravitational wave detectors,such as LISA,TaiJi,and TianQin,to constrain the dimensionless deviating parameter for Einsteindilaton-Gauss-Bonnet(EdGB)gravity with ringdown signals from the merger of binary black holes.The ringdown signal is modeled by the two strongest QNMs in EdGB gravity.Considering time-delay interferometry,we calculate the signal-to-noise ratio of different space-based detectors for ringdown signals to analyze their capabilities.The Fisher information matrix is employed to analyze the accuracy of parameter estimation,with particular focus on the dimensionless deviating parameter for EdGB gravity.The impact of the parameters of gravitational wave sources on the estimation accuracy of the dimensionless deviating parameter is also studied.We find that the constraint ability of EdGB gravity is limited because the uncertainty of the dimensionless deviating parameter increases with a decrease in the dimensionless deviating parameter.LISA and TaiJi offer more advantages in constraining the dimensionless deviating parameter to a more accurate level for massive black holes,whereas TianQin is more suited to less massive black holes.The Bayesian inference method is used to perform parameter estimation on simulated data,which verifies the reliability of the conclusion.

关键词： Einstein-dilaton-Gauss-Bonnet gravity quasinormal modes space-based gravitational-wave detection parameter estimation