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Detecting coherence with respect to general quantum measurements

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Science China(Information Sciences) 2023年第8期66卷 52-60页

作者： Yu-Cheng CHEN Jiong CHENG wen-zhao zhang Cheng-Jie zhang School of Physical Science and Technology Ningbo University State Key Laboratory of Precision Spectroscopy School of Physics and Electronic Science East China Normal University

Quantum coherence is crucial in quantum resource theory. Previous studies have mainly focused on standard coherence based on a complete orthogonal reference. Standard coherence has recently been extended to general positive-operator-valued measure(POVM)-based coherence, including block coherence as a special case. Therefore, it is necessary to construct block and POVM-based coherence witnesses to detect them. In this study, we present witnesses for block and POVM-based coherence and obtain the necessary and sufficient conditions for constructing these witnesses. We also discuss possible realizations of some block and POVM-based coherence witnesses in experiments and present examples of measuring block coherence witnesses based on real experimental data. Furthermore, we present an application of block coherence witnesses in a quantum-parameter estimation task with a degenerate Hamiltonian and estimate the unknown parameter by measuring the block coherence witnesses when the input state is block ***, we prove that the quantum Fisher information of any block-incoherent state equals zero, which coincides with the result obtained from measuring block coherence witnesses.

关键词： coherence witness general quantum measurements block coherence POVM-based coherence quantum coherence

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Double-passage mechanical cooling in a coupled optomechanical system

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Chinese Physics B 2019年第11期28卷 173-178页

作者： Qing-Xia Mu Chao Lang wen-zhao zhang Mathematics and Physics Department North China Electric Power UniversityBeijing 102206China Beijing Computational Science Research Center(CSRC) Beijing 100193China

We consider a three-mode optomechanical system where two cavity modes are coupled to a common mechanical oscillator. We focus on the resolved sideband limit and illustrate the relation between the significant parameters of the system and the instantaneous-state mean phonon number of the oscillator cooled to the ground state, particularly at the early stage of the evolution. It is worth noting that the optical coupling sets up a correlation between the two cavity modes,which has significant effect on the cooling process. Using numerical solutions, we find that the inter-cavity coupling will decrease the cooling effect when both cavities have the same effective optomechanical coupling. However, when the effective optomechanical couplings are different, the cooling effect will be strongly improved by selecting appropriate range of inter-cavity coupling.

关键词： optomechanical system ground-state cooling quantum optics

Non-Markovian Master Equation for Distant Resonators Embedded in a One-Dimensional Waveguide

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Communications in Theoretical Physics 2018年第9期69卷 273-279页

作者： Xin-Yu Chen wen-zhao zhang Chong Li School of Physics Dalian University of TechnologyBeijing Computational Science Research Cente

We develop a master equation approach to describe the dynamics of distant resonators coupled through a one-dimensional waveguide. Our method takes into account the back-actions of the reservoirs, and enables us to calculate the exact dynamics of the complete system at all times. We show that such system can cause nonexponential and long-lived photon decay due to the existence of a relaxation effect. The physical origin of non-Markovianity in our model system is the finite propagation speed resulting in time delays in communication between the nodes, and strong decay rate of the emitters into the waveguide. When the distance satisfies the standing wave condition, we find that when the time delay is increased, the dark modes formation is no longer perfect, and the average photon number of dark mode decreases in steady time limit.

关键词： non-Markovian master equation quantum network waveguide QED

Optomechanical state transfer between two distant membranes in the presence of non-Markovian environments

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Chinese Physics B 2018年第12期27卷 177-181页

作者： Jiong Cheng Xian-Ting Liang wen-zhao zhang Xiangmei Duan Department of Physics Ningbo UniversityNingbo 315211China Beijing Computational Science Research Center (CSRC) Beijing 100193China

The quantum state transfer between two membranes in coupled cavities is studied when the system is surrounded by non-Markovian environments. An analytical approach for describing non-Markovian memory effects that impact on the state transfer between distant membranes is presented. We show that quantum state transfer can be implemented with high efficiency by utilizing the experimental spectral density, and the performance of state transfer in non-Markovian environments is much better than that in Markovian environments, especially when the tunneling strength between the two cavities is not very large.

关键词： optomechanical systems non-Markovian effect quantum state transfer

Nonlocal nonreciprocal optomechanical circulator

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Chinese Physics B 2022年第5期31卷 325-333页

作者： Ji-Hui Zheng Rui Peng Jiong Cheng Jing An wen-zhao zhang School of Mathematical Sciences Guizhou Normal UniversityGuiyang 550025China School of Physical Science and Technology Ningbo UniversityNingbo 315211China School of Physics Dalian University of TechnologyDalian 116024China

A nonlocal circulator protocol is proposed in a hybrid optomechanical *** analogy with quantum communication,using the input-output relationship,we establish the quantum channel between two optical modes with *** three-body nonlocal interaction between the cavity and the two oscillators is obtained by eliminating the optomechanical cavity mode and verifying the Bell-CHSH inequality of continuous *** introducing the phase accumulation between cyclic interactions,the unidirectional transmission of quantum state between the optical mode and two mechanical modes is *** results show that nonreciprocal transmissions are achieved as long as the accumulated phase reaches a certain *** addition,the effective interaction parameters in our system are amplified,which reduces the difficulty of the implementation of our *** research can provide potential applications for nonlocal manipulation and transmission control of quantum platforms.

关键词： optomechanics nonlocality nonreciprocity

The First Ground-based White Light Lunar Polarization Imaging:A New Kind of FeO Observation on the Near Side of the Moon

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Research in Astronomy and Astrophysics 2024年第6期24卷 1-6页

作者： Wei-Nan Wang Jin-Song Ping Ming-Yuan Wang wen-zhao zhang Han-Lin Ye Xing-Wei Han Song-Feng Kou Changchun Observatory National Astronomical ObservatoriesChinese Academy of SciencesChangchun 130117China National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 101408China Astronomy Department Beijing Normal UniversityBeijing 100875China International Center for Climate and Environment Sciences Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China Nanjing Institute of Astronomical Optics and Technology Chinese Academy of SciencesNanjing 210042China

Lunar optical polarization is a fascinating phenomenon that occurs when sunlight reflects off the surface of the Moon and becomes *** study employs a novel split-focus plane polarimetric camera to conduct the initial white light polarimetric observations on the near side of the *** obtained the linear degree of polarization(DOP)parameters of white light by observation from the eastern and western hemispheres of the *** findings indicate that the white light polarization is lower in the lunar highland than in the lunar maria *** the analysis of lunar soil samples,we noticed and determined that the DOP parameters of white light demonstrate high consistency with iron oxide on the *** study may serve as a new diagnostic tool for the Moon.

关键词： techniques:photometric polarization methods:observational Moon

Nonlinearly induced entanglement in dissipatively coupled optomechanical system

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Chinese Physics B 2024年第6期33卷 255-260页

作者：杨文全冷轩程泂张闻钊 Department of Physics Ningbo UniversityNingbo 315211China

Nonlinearly induced steady-state photon–phonon entanglement of a dissipative coupled system is studied in the bistable regime. Quantum dynamical characteristics are analysed by solving the mean-field and fluctuation equations of the system. It is shown that dissipative coupling can induce bistable behaviour for the effective dissipation of the *** suitable parameters, one of the steady states significantly reduces the dissipative effect of the system. Consequently,a larger steady-state entanglement can be achieved compared to linear dynamics. Furthermore, the experimental feasibility of the parameters is analysed. Our results provide a new perspective for the implementation of steady-state optomechanical entanglement.

关键词： entanglement optomechanical system dissipatively coupling

Disease Risks of Childhood Obesity in China

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Biomedical and Environmental Sciences 2005年第6期18卷 401-410页

作者： YAN-PING LI XIAO-GUANG YANG FENG-YING ZHAI JIAN-HUA PIAO wen-HUA zhao JIAN zhang GUAN-SHENG MA National Institute for Nutrition and Food Safety Chinese Center for Disease Control and Prevention 29 Nanwei Road Beijing 100050 China

Objective To estimate the relative risks of dyslipidemia, hypertension, diabetes mellitus, and metabolic syndromes among overweight and obese Chinese children compared with their normal weight counterparts. Methods Overweight and obesity were defined by age- and sex-specific BMI classification reference for Chinese children and adolescents. Pediatric metabolic syndrome （MetS） and each risk factor for MetS were defined using the criteria for US adolescents. Definition of hyper-TC, LDL, and dyslipidemia for adults was applied as well. General linear model factor analysis and chi-square test were used to compare the difference in metabolic indicators among normal weight, overweight, and obese groups. Multiple logistic regression analysis was performed to estimate the odds ratio of metabolic abnormalities between obesity, overweight, and normal weight children, after adjustment for living area, family economic level, age, sex, and daily exercise time and TV watching time, as well as different dietary indices in the model. Results Significant increases in blood lipids, glucose, and blood pressure were found among overweight and obese children as compared with their counterparts with normal weight. By applying WGOC-recommended BMI classification, the risks for hypertriglyceridemia, low HDL and dyslipidemia among overweight children were 1.9, 1.4, and 1.5 times, and was 3.3, 1.5, and 1.8 times among obese groups compared to their counterparts with normal weight after adjustment for age, sex, region, socioeconomic status, physical activity, and dietary intakes. The overweight and obese children （15-17.9 years） had a high-risk of developing hypertension, which was 2.3 and 2.9 times higher than their counterparts with normal weight. Above 90% obese adolescents had abdominal obesity, while less than 1% normal weight ones had abdominal obesity. No obese adolescents were free from any risk factors for MetS, while 36.9% of normal weight adolescents were from the risk factors. 83.

关键词： Chinese obese children Metabolic syndrome (MetS) Hypertension Lipids Relative risk

Upgraded photometric system on the 85-cm telescope at Xinglong station

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Research in Astronomy and Astrophysics 2018年第9期18卷 21-30页

作者： Chun-Hai Bai Jian-Ning Fu Tao-Ran Li Zhou Fan Jiang-Hua Wu Yong zhao Xian-Qun Zeng wen-zhao zhang Peng Qiu Guo-Jie Feng Xiao-Jun Jiang National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China Department of Astronomy Beijing Normal UniversityBeijing 100875China

The 85-cm telescope at Xinglong station is a prime focus system that operates well with high science outputs. The telescope has been upgraded since 2014 with a new corrector, and new filters and camera, which are provided by Beijing Normal University. The filter set is the Johnson-Cousins UBV RI system. We report the test results of the new system including bias, dark current, linearity, gain and readout noise of the CCD camera. Then we derive accurate instrumental calibration coefficients in UBV RI bands with Landolt standard stars during photometric nights. Finally, we give the limiting magnitudes with various exposure times and signal-to-noise ratios for observers as references.

关键词： telescope instrumentation CCD photometry