25 results on '"Cheng-Gang Shao"'
Search Results
2. Bayesian analysis of the stochastic gravitational-wave background with alternative polarizations for space-borne detectors
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Yu Hu, Pan-Pan Wang, Yu-Jie Tan, and Cheng-Gang Shao
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- 2023
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3. Constraining the Symmetron Model with the HUST-2020 Torsion Pendulum Experiment
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Yuan-Ling Zhao, Yu-Jie Tan, Wen-Hao Wu, Jie Luo, and Cheng-Gang Shao
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General Physics and Astronomy - Abstract
The search for dynamically screening the coupling between the scalar field and matter in high-density environment is achievable with the symmetron model. The high-accuracy and short-range gravity experiment is proposed to test the symmetron model. In this Letter, the data of the HUST-2020 torsion pendulum experiment testing the inverse-square law at submillimeter range is analyzed to constrain the symmetron model. The results show that the HUST-2020 experiment is uniquely sensitive to probe the symmetron model with a mass scale of μ=7.2×10^{-3} eV, and the self-coupling parameter λ≲105 is excluded at mass scale M=0.3 TeV. Especially, at the dark energy scale μ=2.4×10^{-3} eV, the constraint at M=1.3 TeV is improved by about 10 times the previous constraints on the torsion pendulum experiment. more...
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- 2022
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4. Modified time-delay interferometry with an optical frequency comb
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Yu-Jie Tan, Ming-Yang Xu, Pan-Pan Wang, Han-Zhong Wu, and Cheng-Gang Shao
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- 2022
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5. Sensitivity functions of space-borne gravitational wave detectors for arbitrary time-delay interferometry combinations regarding nontensorial polarizations
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Yu-Jie Tan, Pan-Pan Wang, Wei-Liang Qian, and Cheng-Gang Shao
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Physics ,Interferometry ,Amplitude ,Spacetime ,Gravitational wave ,General relativity ,Mathematical analysis ,Detector ,ASTROFÍSICA ,Sensitivity (control systems) ,Polarization (waves) - Abstract
Direct observation of gravitational waves offers us numerous novel possibilities to further explore the Universe. In practice, the efficiency of the experimental facility for a given gravitational wave source can be measured in terms of the sensitivity function of the instrument. The latter essentially indicates the least incident amplitude required in order to achieve the desired level of the signal-to-noise ratio. Among others, the resultant sensitivity function depends on the specific polarization state of the incident gravitational wave as well as the spatial layout of the detector and its orientation to the wave source. Theoretically, Einstein's general relativity predicts two tensor polarization modes, from a total of six possible modes arising from an arbitrary perturbation of the spacetime metric. Therefore, in this context, the feasibility of measuring nontensorial polarization states provides access to an alternative theory of gravity. In the present study, we analytically evaluate the response functions for arbitrary time-delay interferometry combinations while enumerating all possible polarization modes. The derivation is accomplished by separating the average on the all-sky solid angle from the remaining expression, which, in turn, gives rise to a few factors independent of the time-delay interferometry combination in question. Moreover, we applied the obtained results to the LISA and TianQin missions, and the asymptotic behavior of the resultant sensitivity functions is analyzed and discussed. Among others, it is observed that, for Sagnac combinations, the averaged response function of the breathing mode attains zero at specific discrete frequencies. Such a frequency value corresponds to a multiple of the reciprocal of the one-way light propagation time along the detector arm, irrelevant to the orientation of the wave source. For all six polarization modes, the present findings can be readily applied to an arbitrary time-delay interferometry combination with improved efficiency and accuracy. more...
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- 2021
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6. Constraining the chameleon model with the HUST-2020 torsion pendulum experiment
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Yu-Jie Tan, Yuan-Ling Zhao, Cheng-Gang Shao, Jie Luo, and Wen-Hao Wu
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Gravitation ,Physics ,Classical mechanics ,Torsion pendulum clock ,Work (physics) ,Fifth force ,Dark energy ,Computer Science::Programming Languages ,Torque ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Parameter space ,Scalar field - Abstract
The chameleon model was proposed as a promising candidate for the dark energy screening mechanism. It is not straightforward to detect the fifth force mediated by the chameleon scalar field in a high-density environment, such as those in a ground-based laboratory. Nevertheless, short-range gravitational experiments such as the torsion pendulum experiment can provide strong constraints on the chameleon model. In this work, we constrain the chameleon model from a precise test of the inverse-square law at Huazhong University of Science and Technology. In particular, we take full advantage of the regular flat-plate structure of the test and attraction mass, which gives rise to accurate modeling for the chameleon force and torque. The derived analytical results on the chameleon torque are shown to agree well with those by numerical calculations. Subsequently, based on the experimental data, the parameter space of the chameleon model is analyzed, and the results are presented in terms of a more stringent constraint on the model parameters. more...
- Published
- 2021
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7. Sensitivity functions of spaceborne gravitational wave detectors for arbitrary time-delay interferometry combinations
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Yu-Jie Tan, Wei-Liang Qian, Cheng-Gang Shao, and Pan-Pan Wang
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Physics ,Interferometry ,Gravitational wave ,Frequency band ,Noise (signal processing) ,Detector ,Statistical physics ,Sensitivity (control systems) ,Polarization (waves) ,ONDAS GRAVITACIONAIS ,Numerical integration - Abstract
The principal aim of the space-based gravitational wave detectors is to explore the gravitational waves in the 0.1 mHz-1 Hz frequency band. To maximize the potential capability of the experimental apparatus regarding the instrument performance, one needs to acquire accurate information on its sensitivity limit. The sensitivity curve in question, by definition, depends on the amplitudes of signal and noise involved in the measurement. In this work, we explicitly derive, under rather universal assumptions irrelevant to the detailed form of the time-delay interferometry combination, general results of the sensitivity functions. The key feature of the present approach is that both the all-sky and polarization average can be factorized and henceforth evaluated analytically. The resultant expressions are then applied to a variety of time-delay interferometry combinations, inclusively for the optimal channels. In particular, the asymptotical forms of the sensitivity functions are obtained at the high and low frequency limits, and the subsequential implications are analyzed. When compared with the approaches in terms of numerical integration, the obtained formulism furnishes a more straightforward as well as efficient access to the relevant signal noise ratios for the spaceborne gravitational wave detectors. more...
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- 2021
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8. Scheme of G measurement with large amplitude torsion pendulum
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Rui-qi Liu, Qing Li, Jian-Ping Liu, Cheng-Gang Shao, Yang Lei, Dong Li, and Jie Luo
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Physics ,Basis (linear algebra) ,010308 nuclear & particles physics ,Mathematical analysis ,Value (computer science) ,Harmonic (mathematics) ,01 natural sciences ,Measure (mathematics) ,Amplitude ,Torsion pendulum clock ,Scheme (mathematics) ,0103 physical sciences ,Component (group theory) ,010306 general physics - Abstract
In the recent CODATA-2014 adjustment, the $G$ values obtained by different groups are not in good agreement with each other within respective uncertainties, which may be attributed to the possible unknown or incorrectly evaluated systematic errors in different methods. This paper proposes a scheme to measure $G$ with two independent methods. The first method is the extraction of the $G$ value from the fundamental periods of the torsion pendulum, with the source masses at two positions; the other one determines the $G$ value on the basis of the amplitude of the third-order harmonic component of the torsion pendulum. Both methods are performed with the same setup by using the large-amplitude torsion pendulum. Through theoretical derivation and simulation, the uncertainties of the $G$ values obtained by the two methods are both expected to be within 20 ppm. By comparing the $G$ values from the two methods, we can explore the potential systematic errors in the measurement. more...
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- 2020
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9. Sensitivity functions for space-borne gravitational wave detectors
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Yu-Jie Tan, Xiao-Yu Lu, and Cheng-Gang Shao
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Physics ,Brewster's angle ,Orientation (computer vision) ,business.industry ,Gravitational wave ,Detector ,FOS: Physical sciences ,General Relativity and Quantum Cosmology (gr-qc) ,Space (mathematics) ,Signal ,General Relativity and Quantum Cosmology ,symbols.namesake ,Interferometry ,Optics ,symbols ,Sensitivity (control systems) ,business - Abstract
Time-delay interferometry is put forward to improve the signal-to-noise ratio of space-borne gravitational wave detectors by canceling the large laser phase noise with different combinations of measured data. Based on the Michelson data combination, the sensitivity function of the detector can be obtained by averaging the all-sky wave source positions. At present, there are two main methods to encode gravitational wave signal into detector. One is to adapt gravitational wave polarization angle depending on the arm orientation in the gravitational wave frame, and the other is to divide the gravitational wave signal into plus and cross polarizations in the detector frame. Although there are some attempts using the first method to provide the analytical expression of sensitivity function, only a semianalytical one could be obtained. Here, starting with the second method, we demonstrate the equivalence of both methods. First time to obtain the full analytical expression of sensitivity function, which provides a fast and accurate mean to evaluate and compare the performance of different space-borne detectors, such as LISA and TianQin. more...
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- 2019
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10. Test of higher-derivative gravitational relativistic models with the gravitational inverse-square law experiments
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Ya-Fen Chen, Yu-Jie Tan, Cheng-Gang Shao, and Cheng-Gang Qin
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Physics ,Gravity (chemistry) ,010308 nuclear & particles physics ,Group (mathematics) ,General relativity ,Lambda ,01 natural sciences ,Gravitation ,General Relativity and Quantum Cosmology ,Quantum nonlocality ,Torsion pendulum clock ,0103 physical sciences ,Torsion (algebra) ,010306 general physics ,Mathematical physics - Abstract
The theory of general relativity has an ultraviolet(UV) problem that can be ameliorated by gravity with higher derivatives. The four-derivative gravity as an effective gravitational theory at UV scalars has two Yukawa-like corrections with parameters ${\ensuremath{\lambda}}_{0}$ and ${\ensuremath{\lambda}}_{2}$. By the analysis of experiments of HUST-2015, Newman's group, lake experiment, and Cassini spacecraft, we obtain the strong-bound regions for these parameters at submillimeter-to-millimeter, centimeter-to-meter, tens-of-meter, and solar-system scales, in which the properties of potential are clearly shown. Recently, the ghostfree and singularityfree gravity, a more potential modified gravity theory, introduces the novel conception of nonlocality. We test the scale of gravitational nonlocality ${\ensuremath{\lambda}}_{\mathrm{m}}l2.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}\text{ }\text{ }\mathrm{m}$ by the torsion pendulum experiment HUST-2015. The predicted decaying spatial oscillations are visible meaning possible violation at shorter ranges. Our result provides useful information for gravitational interaction at microscopic ranges. more...
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- 2019
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11. Test of special relativity using comparisons of clock frequencies
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Yu-Jie Tan, Ya-Jie Wang, Xiao-Yu Lu, and Cheng-Gang Shao
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010309 optics ,Physics ,Theoretical physics ,0103 physical sciences ,010306 general physics ,01 natural sciences ,Special relativity (alternative formulations) ,Test (assessment) - Published
- 2018
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12. Improved frequency-shift gravity-gradient compensation on canceling the Raman-pulse-duration effect in atomic gravimeters
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Cheng-Gang Shao, Zhong-Kun Hu, Ya-Jie Wang, Yu-Jie Tan, and Xiao-Yu Lu
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Physics ,Atom interferometer ,010308 nuclear & particles physics ,Gravimeter ,Pulse duration ,Kinematics ,Coupling (probability) ,01 natural sciences ,Compensation (engineering) ,Computational physics ,symbols.namesake ,0103 physical sciences ,symbols ,Equivalence principle ,Einstein ,010306 general physics - Abstract
Although frequency-shift gravity-gradient compensation is currently the technique with the most potential to test the weak equivalence principle with atom interferometry at high precision, it faces an unavoidable obstacle on how to cancel the coupling between the Raman-pulse-duration effect and the gravity gradient related to the atomic initial kinematics. According to the Einstein equivalence principle, we develop a method to calculate this coupling effect in a space-stretching free-falling frame, based on which an improved frequency-shift gravity-gradient compensation technique is put forward to make high-accuracy weak-equivalence-principle tests with the microscopic particles, such as at the level of ${10}^{\ensuremath{-}14}$, more possible. more...
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- 2018
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13. Publisher’s Note: Test of non-Newtonian gravitational forces at micrometer range with two-dimensional force mapping [Phys. Rev. D 94 , 122005 (2016)]
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Cheng-Gang Shao, Pengshun Luo, Jianbo Wang, Wenjie Wu, Shan-Qing Yang, Aizi Jin, Sheng-Guo Guan, Jun Luo, Zhaoyang Tian, and Kai Chen
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Physics ,Gravitation ,Micrometre ,Range (particle radiation) ,Classical mechanics ,Force mapping ,Non-Newtonian fluid - Published
- 2018
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14. Time delay and the effect of the finite speed of light in atom gravimeters
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Zhong-Kun Hu, Cheng-Gang Shao, and Yu-Jie Tan
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Physics ,Propagation time ,Gravimeter ,01 natural sciences ,Speed of light (cellular automaton) ,Pulse time ,Computational physics ,Pulse (physics) ,010309 optics ,Interferometry ,Quantum mechanics ,Atom (measure theory) ,0103 physical sciences ,Wave vector ,010306 general physics - Abstract
The propagation time delay due to the finite speed of light (FSL) in atom gravimeters introduces a bias in the gravity measurement, as well as that in classical free-falling corner-cube gravimeters, which is usually termed the FSL effect. For a typical atom gravimeter, the FSL time delay is about several nanoseconds, resulting in the FSL effect, a non-negligible bias in the gravity-acceleration measurement. However, a time delay of about several microseconds, achieved by controlling the Raman-pulse timing directly, contributes a negligible effect. This interesting phenomenon motivates us to make clear two questions: first, what are the origins of the FSL effect in atom gravimeters, and second, what is the difference between the two time delays? Our analysis shows that the FSL effect in atom gravimeters is not just a matter of FSL time delay to a great extent but also the change in the effective wave vector; moreover, the FSL time delay can be quantitatively regarded as the same as the pulse time delay since both actually affect the gravity measurement by changing the two interferometer pulse separations. more...
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- 2017
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15. General post-Minkowskian expansion and application of the phase function
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Cheng-Gang Qin and Cheng-Gang Shao
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Physics ,Space technology ,Series (mathematics) ,010308 nuclear & particles physics ,Perturbation (astronomy) ,Observable ,01 natural sciences ,Space exploration ,Gravitational constant ,Classical mechanics ,Gravitational field ,0103 physical sciences ,Point (geometry) ,010303 astronomy & astrophysics - Abstract
The phase function is a useful tool to study all observations of space missions, since it can give all the information about light propagation in a gravitational field. For the extreme accuracy of the modern space missions, a precise relativistic modeling of observations is required. So, we develop a recursive procedure enabling us to expand the phase function into a perturbative series of ascending powers of the Newtonian gravitational constant. Any $n$th-order perturbation of the phase function can be determined by the integral along the straight line connecting two point events. To illustrate the result, we carry out the calculation of the phase function outside a static, spherically symmetric body up to the order of ${G}^{2}$. Then, we develop a precise relativistic model that is able to calculate the phase function and the derivatives of the phase function in the gravitational field of rotating and uniformly moving bodies. This model allows the computing of the Doppler, radio science, and astrometric observables of the space missions in the Solar System. With the development of space technology, the relativistic corrections due to the motion of a planet's spin must be considered in the high-precision space missions in the near future. As an example, we give the estimates of the relativistic corrections on the observables about the space missions TianQin and BEACON. more...
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- 2017
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16. Relativistic effects in atom gravimeters
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Yu-Jie Tan, Zhong-Kun Hu, and Cheng-Gang Shao
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Physics ,Atom interferometer ,010308 nuclear & particles physics ,01 natural sciences ,Matrix (mathematics) ,Interferometry ,Tests of general relativity ,0103 physical sciences ,Atom ,Astronomical interferometer ,Sensitivity (control systems) ,Atomic physics ,010306 general physics ,Relativistic quantum chemistry - Abstract
Atom interferometry is currently developing rapidly, which is now reaching sufficient precision to motivate laboratory tests of general relativity. Thus, it is extremely significant to develop a general relativistic model for atom interferometers. In this paper, we mainly present an analytical derivation process and first give a complete vectorial expression for the relativistic interferometric phase shift in an atom interferometer. The dynamics of the interferometer are studied, where both the atoms and the light are treated relativistically. Then, an appropriate coordinate transformation for the light is performed crucially to simplify the calculation. In addition, the Bord\'e $ABCD$ matrix combined with quantum mechanics and the ``perturbation'' approach are applied to make a methodical calculation for the total phase shift. Finally, we derive the relativistic phase shift kept up to a sensitivity of the acceleration $\ensuremath{\sim}1{0}^{\ensuremath{-}14}\text{ }\text{ }{\mathrm{m}/\mathrm{s}}^{2}$ for a $10\text{\ensuremath{-}}\mathrm{m}$-long atom interferometer. more...
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- 2017
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17. Finite-speed-of-light perturbation in atom gravimeters
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Yu-Jie Tan, Zhong-Kun Hu, and Cheng-Gang Shao
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Physics ,Systematic error ,Gravimeter ,Coordinate system ,Perturbation (astronomy) ,01 natural sciences ,Physics::Geophysics ,010309 optics ,Quantum electrodynamics ,0103 physical sciences ,Physics::Atomic and Molecular Clusters ,Physics::Atomic Physics ,010306 general physics ,Relativistic quantum chemistry - Abstract
The finite-speed-of-light (FSL) effect is a systematic error in atom gravimeters arising from the time delay due to the propagation of the light. It includes the frequency-chirp-independent part and the frequency-chirp-dependent part, which were not considered completely. The FSL effect in atom gravimeters is different from that in corner-cube absolute gravimeters. In the past, this effect has been widely studied in corner-cube absolute gravimeters, whereas little has been discussed about and done with atom gravimeters. In this paper, we mainly propose a complete analytical study based on a coordinate transformation and on a ``perturbation'' approach to estimate this effect in an atom gravimeter. This also offers the potential to calculate the general relativistic effects in atom gravimeters. In addition, a comparison with a crude ``average-path'' analysis is given for a particular case of the FSL effect in atom gravimeters. more...
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- 2016
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18. Atomic multiwave interferometer for Aharonov-Casher-phase measurements
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Cheng-Gang Shao, Zhong-Kun Hu, Yi Ke, Min-Kang Zhou, Ke Zhang, and Xiao-Chun Duan
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Physics ,Photon ,Astrophysics::Instrumentation and Methods for Astrophysics ,Phase (waves) ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,01 natural sciences ,010309 optics ,Interferometry ,symbols.namesake ,Geometric phase ,Stark effect ,0103 physical sciences ,symbols ,Invariant mass ,Physics::Atomic Physics ,Atomic physics ,010306 general physics ,Hyperfine structure ,Noise (radio) - Abstract
We present an atomic multiwave interferometer with magnetic sublevels to precisely determine the Aharonov-Casher (AC) geometric phase. Simulations show that this interferometer has sharper fringes than a normal two-wave interferometer, which means a higher phase resolution can be achieved. Moreover, atoms evolving in a single hyperfine structure state make the interferometer insensitive to the dc Stark phase shift. This dc Stark shift is one of the main noise sources in AC phase measurements. The constraint of the photon rest mass is also discussed when using this atomic interferometer to measure the Aharonov-Casher phase. more...
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- 2016
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19. Noise limit of a torsion pendulum under optomechanical control
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Yu-Jie Tan, Cheng-Gang Shao, and Zhong-Kun Hu
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Physics ,Rigidity (electromagnetism) ,Torsion pendulum clock ,Limit (music) ,Pendulum ,High resolution ,Torsion (mechanics) ,Mechanics ,Noise (electronics) ,Atomic and Molecular Physics, and Optics ,Metrology - Abstract
In most torsion pendulum experiments, the force resolution is dominantly limited by thermal noise, which is proportional to the pendulum's intrinsic rigidity. Thus, increasing the rigidity directly, such as through increasing torsion fiber's diameter, will decrease the resolution. Here, we present a method to improve the rigidity of a pendulum indirectly through optomechanical control. In this method, for appropriate typical parameter values, the rigidity can be improved greatly. Meanwhile, the extra noise introduced, which our analysis focuses on, can be regulated within the thermal noise level, i.e., the force resolution may not decrease after optomechanical control. This can balance the conflict between large rigidity and high resolution. more...
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- 2015
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20. New determination of the gravitational constantGwith time-of-swing method
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Qing-Lan Wang, Lin-Xia Liu, Qing Li, Shan-Qing Yang, Jun Luo, Liang-Cheng Tu, Cheng-Gang Shao, and Qi Liu
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Physics ,Gravitational constant ,Gravitation ,Nuclear and High Energy Physics ,Normal mode ,Quantum mechanics ,Torsion pendulum clock ,Mathematical analysis ,Torsion (mechanics) ,SPHERES ,Swing ,Moment of inertia - Abstract
A new determination of the Newtonian gravitational constant $G$ is presented by using a torsion pendulum with the time-of-swing method. Compared with our previous measurement with the same method, several improvements greatly reduced the uncertainties as follows: (i) two stainless steel spheres with more homogeneous density are used as the source masses instead of the cylinders used in the previous experiment, and the offset of the mass center from the geometric center is measured and found to be much smaller than that of the cylinders; (ii) a rectangular glass block is used as the main body of the pendulum, which has fewer vibration modes and hence improves the stability of the period and reduces the uncertainty of the moment of inertia; (iii) both the pendulum and source masses are placed in the same vacuum chamber to reduce the error of measuring the relative positions; (iv) changing the configurations between the ``near'' and ``far'' positions is remotely operated by using a stepper motor to lower the environmental disturbances; and (v) the anelastic effect of the torsion fiber is first measured directly by using two disk pendulums with the help of a high-$Q$ quartz fiber. We have performed two independent $G$ measurements, and the two $G$ values differ by only 9 ppm. The combined value of $G$ is $(6.673\text{ }49\ifmmode\pm\else\textpm\fi{}0.000\text{ }18)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}\text{ }\text{ }{\mathrm{m}}^{3}\text{ }{\mathrm{kg}}^{\ensuremath{-}1}\text{ }{\mathrm{s}}^{\ensuremath{-}2}$ with a relative uncertainty of 26 ppm. more...
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- 2010
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21. Determination of the Newtonian Gravitational ConstantGwith Time-of-Swing Method
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Ya-Ting Zhang, Qi Liu, Jun Luo, Shan-Qing Yang, Qing Li, Cheng-Gang Shao, Liang-Cheng Tu, and Lin-Xia Liu
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Gravitational constant ,Physics ,Normal mode ,Gravitational wave ,Quantum mechanics ,Newtonian fluid ,Block (permutation group theory) ,General Physics and Astronomy ,Standard uncertainty ,Inertial moment - Abstract
We present a new value of the Newtonian gravitational constant $G$ by using the time-of-swing method. Several improvements greatly reduce the uncertainties: (1) measuring the anelasticity of the fiber directly; (2) using spherical source masses minimizes the effects of density inhomogeneity and eccentricities; (3) using a quartz block pendulum simplifies its vibration modes and minimizes the uncertainty of inertial moment; (4) setting the pendulum and source masses both in a vacuum chamber reduces the error of measuring the relative positions. By two individual experiments, we obtain $G=6.673\text{ }49(18)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}11}\text{ }\text{ }{\mathrm{m}}^{3}\text{ }{\mathrm{kg}}^{\ensuremath{-}1}\text{ }{\mathrm{s}}^{\ensuremath{-}2}$ with a standard uncertainty of about 2.6 parts in ${10}^{5}$. more...
- Published
- 2009
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22. Constraints on somef(R)gravity models in the Palatini formalism from a time-varying gravitational constant
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Cheng-Bing Li, Cheng-Gang Shao, and Zhong-Zhu Liu
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Gravitation ,Physics ,Gravitational constant ,Nuclear and High Energy Physics ,Big Bang nucleosynthesis ,Quantum mechanics ,Dark matter ,Dark energy ,f(R) gravity ,Redshift ,Mathematical physics ,Scalar curvature - Abstract
In this work, we studied how the relative variation of the gravitational constant |G/G|{sub 0} at the redshift z=0 restricts model parameters in Palatini f(R) gravity. According to results from the observation of big bang nucleosynthesis and the anisotropies in the cosmic microwave background radiation, the ratio that gives the general constraint condition on the f(R) model is taken to be |G/G|{sub 0} more...
- Published
- 2009
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23. Null Test of Newtonian Inverse-Square Law at Submillimeter Range with a Dual-Modulation Torsion Pendulum
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Liang-Cheng Tu, Lin-Xia Liu, Jun Luo, Cheng-Gang Shao, and Sheng-Guo Guan
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Physics ,Length scale ,General Relativity and Quantum Cosmology ,Classical mechanics ,Torsion pendulum clock ,Null (mathematics) ,Yukawa potential ,Inverse-square law ,Newtonian fluid ,General Physics and Astronomy ,Space (mathematics) ,Lambda - Abstract
A null experimental test of the Newtonian inverse-square law at submillimeter range using a torsion pendulum was presented. Under the dual modulations of both the expected signal and the gravitational torque for calibration, our data concluded with 95% confidence that no new forces were observed and any gravitational-strength Yukawa forces (|alpha|or=1) must have a length scale lambda66 microm, agreeing well with the latest result of the Eöt-wash group. Our result sets a unification energy scale of M*or=2.8 TeV/c2 for the two compactified extra space dimensions with the same size R*47 microm. more...
- Published
- 2007
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24. Repulsive Casimir effect between anisotropic dielectric and permeable plates
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Da-Lei Zheng, Cheng-Gang Shao, and Jun Luo
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Casimir effect ,Physics ,Permittivity ,Casimir pressure ,Condensed matter physics ,Permeability (electromagnetism) ,Physics::Optics ,Torque ,Dielectric ,Physics::Classical Physics ,Anisotropy ,Electromagnetic radiation ,Atomic and Molecular Physics, and Optics - Abstract
The quantized surface mode technique was used to calculate the zero-point energy between two anisotropic parallel plates with nontrivial magnetic properties, one of which is dielectric and the other of which is permeable. The analytical approximate expressions of Casimir force and torque were obtained in the retarded limit. The repulsive Casimir effect can be acquired for some materials with suitable permittivities and permeabilities, which might be measured in a future experiment. more...
- Published
- 2006
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25. Casimir torque between two birefringent plates
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Ai-Hong Tong, Cheng-Gang Shao, and Jun Luo
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Permittivity ,Casimir effect ,Physics ,Birefringence ,Vacuum energy ,Quantum mechanics ,Torque ,Limit (mathematics) ,Atomic and Molecular Physics, and Optics ,Surface mode - Abstract
The vacuum energy between two birefringent plates was calculated using the quantized surface mode technique. And an analytical approximate expression of Casimir torque was obtained in the retarded limit, which is found to vary as sin(2{phi}) with {phi}, the angle between the two optical axes. This result is a supplement to the numerical calculation obtained by Munday, Iannuzzi, Barash, and Capasso [Phys. Rev. A. 71, 042102 (2005)]. more...
- Published
- 2005
- Full Text
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