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A Fully Symmetrical Quantum Key Distribution System Capable of Preparing and Measuring Quantum States* Supported by the Fundamental Research Funds for the Central Universities (Grant No. 2019XD-A02), and the State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications (Grant No. IPO2019ZT06).
天琦 窦,吉鹏 王,振华 李,文秀 屈,舜禹 杨,钟齐 孙,芬 周,雁鑫 韩,雨晴 黄,海强 马
Chin. Phys. Lett. 2020, 37 (11):
0
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DOI: 10.1088/0256-307X/37/11/110301
We propose a fully symmetrical QKD system that enables quantum states to be prepared and measured simultaneously without compromising system performance. Over a 25.6 km fiber channel, we demonstrate point-to-point QKD operations with asymmetric Mach–Zehnder interferometer modules. Two interference visibilities of above 99% indicate that the proposed system has excellent stability. Consequently, the scheme not only improves the feasibility of distributing secret keys, but also enables QKD closer to more practical applications.
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Mutual Restriction between Concurrence and Intrinsic Concurrence for Arbitrary Two-Qubit States
A-Long Zhou , Dong Wang, Xiao-Gang Fan , Fei Ming , and Liu Ye
Chin. Phys. Lett. 2020, 37 (11):
110302
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DOI: 10.1088/0256-307X/37/11/110302
Concurrence is viewed as the most commonly approach for quantifying entanglement of two-qubit states, while intrinsic concurrence contains concurrence of four pure states consisting of a special pure state ensemble concerning an arbitrary two-qubit state. Thus, a natural question arises: Whether there is a specified relation between them. We firstly examine the relation between concurrence and intrinsic concurrence for the maximally nonlocal mixed state under a special unitary operation, which is not yet rigorously proved. In order to obtain a general result, we investigate the relation between concurrence and intrinsic concurrence using randomly generated two-qubit states, and derive an inequality relation between them. Finally, we take into account the relation between concurrence and intrinsic concurrence in open systems, and reveal the ratio of the two quantum resources, which is only correlated with the experiencing channels.
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Possible Candidates for Chirality in the Odd-Odd As Isotopes
Chen Liu , Shouyu Wang, Bin Qi , and Hui Jia
Chin. Phys. Lett. 2020, 37 (11):
112101
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DOI: 10.1088/0256-307X/37/11/112101
The deformations and the corresponding configurations of the odd-odd As isotopes are investigated using the adiabatic and configuration-fixed constrained triaxial relativistic mean field (RMF) theory. Energy minima with triaxial deformations and high-$j$ particle-hole configurations are obtained in $^{72,74,76,78,80}$As, where the chiral doublet bands are possible to appear. The existence of multiple chiral doublet (M$\chi$D) is demonstrated in $^{74,76,78}$As. Based on the calculated single-particle levels, we also find possible coexistence of chiral and pseudospin symmetries in the odd-odd As isotopes.
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Reaction Rate Weighted Multilayer Nuclear Reaction Network
Huan-Ling Liu, Ding-Ding Han, Peng Ji, and Yu-Gang Ma
Chin. Phys. Lett. 2020, 37 (11):
112601
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DOI: 10.1088/0256-307X/37/11/112601
Nuclear reaction rate $\lambda$ is a significant factor in processes of nucleosyntheses. A multi-layer directed-weighted nuclear reaction network, in which the reaction rate is taken as the weight, and neutron, proton, $^4$He and the remainder nuclei as the criteria for different reaction layers, is for the first time built based on all thermonuclear reactions in the JINA REACLIB database. Our results show that with the increase in the stellar temperature $T_{9}$, the distribution of nuclear reaction rates on the R-layer network demonstrates a transition from unimodal to bimodal distributions. Nuclei on the R-layer in the region of $\lambda = [1,2.5\times10^{1}]$ have a more complicated out-going degree distribution than that in the region of $\lambda = [10^{11},10^{13}]$, and the number of involved nuclei at $T_{9} = 1$ is very different from the one at $T_{9} = 3$. The redundant nuclei in the region of $\lambda = [1, 2.5\times10^{1}]$ at $T_{9} = 3$ prefer $(\gamma,{\rm p})$ and $({\gamma,\alpha})$ reactions to the ones at $T_{9}=1$, which produce nuclei around the $\beta$ stable line. This work offers a novel way to the big-data analysis on the nuclear reaction network at stellar temperatures.
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Semi-Ellipsoid Nanoarray for Angle-Independent Plasmonic Color Printing
Jiancai Xue , Limin Lin , Zhang-Kai Zhou, and Xue-Hua Wang
Chin. Phys. Lett. 2020, 37 (11):
114201
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DOI: 10.1088/0256-307X/37/11/114201
Employing a silver nano semi-ellipsoid nanoarray with high symmetry into applications in plasmonic color printing, we fulfill printing images with colors independent of observing angles. Also, by decreasing the period of a nano semi-ellipsoid array into deep-subwavelength scales, we obtain high reflectivity over 50%, promising high efficiency for imaging generations. A facile technique based on the transfer of anodized aluminum oxide template is developed to fabricate the silver nano semi-ellipsoid nanoarray, realizing plasmonic color printing with features of low cost, scalable, full color and high flexibility. Our approach provides a feasible way to address the angle-dependent issue in the previous practice of plasmonic color printing, and boosts this field on its way to real-world commercial applications.
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Rapid Measurement and Control of Nitrogen-Vacancy Center-Axial Orientation in Diamond Particles
Guobin Chen, Yang Hui, Junci Sun, Wenhao He, and Guanxiang Du
Chin. Phys. Lett. 2020, 37 (11):
114203
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DOI: 10.1088/0256-307X/37/11/114203
Determination and control of nitrogen-vacancy (NV) centers play an important role in sensing the vector field by using their quantum information. To measure orientation of NV centers in a diamond particle attached to a tapered fiber rapidly, we propose a new method to establish the direction cosine matrix between the lab frame and the NV body frame. In this method, only four groups of the ODMR spectrum peaks shift data need to be collected, and the magnetic field along $\pm Z$ and $\pm Y$ in the lab frame is applied in the meantime. We can also control any NV axis to rotate to the $X$, $Y$, $Z$ axes in the lab frame according to the elements of this matrix. The demonstration of the DC and microwave magnetic field vector sensing is presented. Finally, the proposed method can help us to perform vector magnetic field sensing more conveniently and rapidly.
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Tuning the Water Desalination Performance of Graphenic Layered Nanomaterials by Element Doping and Inter-Layer Spacing
Fuxin Wang, Chao Zhang, Yanmei Yang, Yuanyuan Qu, Yong-Qiang Li, Baoyuan Man, and Weifeng Li
Chin. Phys. Lett. 2020, 37 (11):
116101
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DOI: 10.1088/0256-307X/37/11/116101
Through atomic molecular dynamics simulations, we investigate the performance of two graphenic materials, boron (BC$_{3}$) and nitrogen doped graphene (C$_{3}$N), for seawater desalination and salt rejection, and take pristine graphene as a control. Effects of inter-layer separation have been explored. When water is filtered along the transverse directions of three-layered nanomaterials, the optimal inter-layer separation is 0.7–0.9 nm, which results in high water permeability and salt obstruction capability. The water permeability is considerably higher than porous graphene filter, and is about two orders of magnitude higher than commercial reverse osmosis (RO) membrane. By changing the inter-layer spacing, the water permeability of three graphenic layered nanomaterials follows an order of C$_{3}$N $\ge$ GRA $>$ BC$_{3}$ under the same working conditions. Amongst three nanomaterials, BC$_{3}$ is more sensitive to inter-layer separation which offers a possibility to control the water desalination speed by mechanically changing the membrane thickness. This is caused by the intrinsic charge transfer inside BC$_{3}$ that results in periodic distributed water clusters around the layer surface. Our present results reveal the high potentiality of multi-layered graphenic materials for controlled water desalination. It is hopeful that the present work can guide design and fabrication of highly efficient and tunable desalination architectures.
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Distinct Three-Level Spin–Orbit Control Associated with Electrically Controlled Band Swapping
Yu Suo, Hao Yang, and Jiyong Fu
Chin. Phys. Lett. 2020, 37 (11):
117101
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DOI: 10.1088/0256-307X/37/11/117101
We investigate the Rashba and Dressehaus spin–orbit (SO) couplings in an ordinary GaAs/AlGaAs asymmetric double well, which favors the electron occupancy of three subbands $\nu=1,2,3$. Resorting to an external gate, which adjusts the electron occupancy and the well symmetry, we demonstrate distinct three-level SO control of both Rashba ($\alpha_\nu$) and Dresselhaus ($\beta_\nu$) {intraband} terms. Remarkably, as the gate varies, the first-subband SO parameters $\alpha_1$ and $\beta_1$ comply with the usual linear behavior, while $\alpha_2$ ($\beta_2$) and $\alpha_3$ ($\beta_3$) respectively for the second and third subbands interchange the values, triggered by a gate controlled band swapping. This provides a pathway towards fascinating selective SO control in spintronic applications. Moreover, we observe that the {interband} Rashba ($\eta_{\mu\nu}$) and Dresselhaus ($\varGamma_{\mu\nu}$) terms also exhibit contrasting gate dependence. Our results should stimulate experiments probing SO couplings in multi-subband wells and adopting relevant SO features in future spintronic devices.
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Quasi-One-Dimensional Free-Electron-Like States Selected by Intermolecular Hydrogen Bonds at the Glycine/Cu(100) Interface
Linwei Zhou, Chen-Guang Wang, Zhixin Hu, Xianghua Kong, Zhong-Yi Lu, Hong Guo, and Wei Ji
Chin. Phys. Lett. 2020, 37 (11):
117301
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DOI: 10.1088/0256-307X/37/11/117301
We carry out ab initio density functional theory calculations to study manipulation of electronic structures of self-assembled molecular nanostructures on metal surfaces by investigating the geometric and electronic properties of glycine molecules on Cu(100). It is shown that a glycine monolayer on Cu(100) forms a two-dimensional hydrogen-bonding network between the carboxyl and amino groups of glycine using a first principles atomistic calculation on the basis of a recently found structure. This network includes at least two hydrogen-bonding chains oriented roughly perpendicular to each other. Through molecule–metal electronic hybridization, these two chains selectively hybridized with the two isotropic degenerate Cu(100) surface states, leading to two anisotropic quasi-one-dimensional surface states. Electrons occupying these two states can near-freely move from a molecule to its adjacent molecules directly through the intermolecular hydrogen bonds, rather than mediated by the substrate. This results in the experimentally observed anisotropic free-electron-like behavior. Our results suggest that hydrogen-bonding chains are likely candidates for charge conductors.
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State-Dependent Topological Invariants and Anomalous Bulk-Boundary Correspondence in Non-Hermitian Topological Systems with Generalized Inversion Symmetry
Xiao-Ran Wang , Cui-Xian Guo , Qian Du , and Su-Peng Kou
Chin. Phys. Lett. 2020, 37 (11):
117303
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DOI: 10.1088/0256-307X/37/11/117303
Breakdown of bulk-boundary correspondence in non-Hermitian (NH) topological systems with generalized inversion symmetries is a controversial issue. The non-Bloch topological invariants determine the existence of edge states, but fail to describe the number and distribution of defective edge states in non-Hermitian topological systems. The state-dependent topological invariants, instead of a global topological invariant, are developed to accurately characterize the bulk-boundary correspondence of the NH systems, which is very different from their Hermitian counterparts. At the same time, we obtain the accurate phase diagram of the one-dimensional non-Hermitian Su–Schrieffer–Heeger model with a generalized inversion symmetry from the state-dependent topological invariants. Therefore, these results will be helpful for understanding the exotic topological properties of various non-Hermitian systems.
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Superconductor-Metal Quantum Transition at the EuO/KTaO$_{3}$ Interface
Yang Ma, Jiasen Niu, Wenyu Xing, Yunyan Yao, Ranran Cai, Jirong Sun, X. C. Xie, Xi Lin, and Wei Han
Chin. Phys. Lett. 2020, 37 (11):
117401
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DOI: 10.1088/0256-307X/37/11/117401
We report the experimental investigation of the superconductor-metal quantum phase transition of the EuO/KTaO$_{3}$ interface. Around the transition, a divergence of the dynamical critical exponent is observed, which supports the quantum Griffiths singularity in the EuO/KTaO$_{3}$ interface. The quantum Griffiths singularity could be attributed to large rare superconducting regions and quenched disorders at the interface. Our results could pave the way for studying the exotic superconducting properties at the EuO/KTaO$_{3}$ interface.
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Field- and Current-Driven Magnetization Reversal and Dynamic Properties of CoFeB-MgO-Based Perpendicular Magnetic Tunnel Junctions
Qingwei Fu, Kaiyuan Zhou, Lina Chen, Yongbing Xu, Tiejun Zhou, Dunhui Wang, Kequn Chi, Hao Meng, Bo Liu, Ronghua Liu, and Youwei Du
Chin. Phys. Lett. 2020, 37 (11):
117501
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DOI: 10.1088/0256-307X/37/11/117501
We report a perpendicular magnetic tunnel junction (pMTJ) cell with a tunnel magnetoresistance (TMR) ratio of nearly 200% at room temperature based on CoFeB/Ta/CoFeB as the free layer (FL) and a synthetic antiferromagnetic (SAF) multilayer [Pt/Co]/Ru/[Pt/Co]/Ta/CoFeB as the reference layer (RL). The field-driven magnetization switching measurements show that the pMTJs exhibit an anomalous TMR hysteresis loop. The spin-polarized layer CoFeB of SAF-RL has a lower critical switching field than that of FL. The reason is related to the interlayer exchange coupling (IEC) through a moderately thick Ta spacer layer among SAF-RLs, which generates a moderate and negative bias magnetic field on CoFeB of RL. However, the IEC among RLs has a negligible influence on the current-driven magnetization switching of FL and its magnetization dynamics.
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Comparison of Proton Shower Developments in the BGO Calorimeter of the Dark Matter Particle Explorer between GEANT4 and FLUKA Simulations
Wei Jiang, Chuan Yue, Ming-Yang Cui, Xiang Li, Qiang Yuan, Francesca Alemanno, Paolo Bernardini, Giovanni Catanzani, Zhan-Fang Chen, Ivan De Mitri, Tie-Kuang Dong, Giacinto Donvito, David Francois Droz, Piergiorgio Fusco, Fabio Gargano, Dong-Ya Guo, Dimitrios Kyratzis, Shi-Jun Lei, Yang Liu, Francesco Loparco, Peng-Xiong Ma, Giovanni Marsella, Mario Nicola Mazziotta, Xu Pan, Wen-Xi Peng, Antonio Surdo, Andrii Tykhonov, Yi-Yeng Wei, Yu-Hong Yu, Jing-Jing Zang, Ya-Peng Zhang, Yong-Jie Zhang, and Yun-Long Zhang
Chin. Phys. Lett. 2020, 37 (11):
119601
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DOI: 10.1088/0256-307X/37/11/119601
The DArk Matter Particle Explorer (DAMPE) is a satellite-borne detector for high-energy cosmic rays and $\gamma$-rays. To fully understand the detector performance and obtain reliable physical results, extensive simulations of the detector are necessary. The simulations are particularly important for the data analysis of cosmic ray nuclei, which relies closely on the hadronic and nuclear interactions of particles in the detector material. Widely adopted simulation softwares include the GEANT4 and FLUKA, both of which have been implemented for the DAMPE simulation tool. Here we describe the simulation tool of DAMPE and compare the results of proton shower properties in the calorimeter from the two simulation softwares. Such a comparison gives an estimate of the most significant uncertainties of our proton spectral analysis.
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22 articles
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