检索结果-南通市图书馆

Experimental observation of spontaneous symmetry breaking in a quantum phase transition

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2024年第2期67卷 34-39页

作者： Wen Ning Ri-Hua Zheng Jia-Hao Lu Fan Wu Zhen-Biao Yang Shi-Biao Zheng Fujian Key laboratory of quantum information and quantum Optics College of Physics and Information EngineeringFuzhou UniversityFuzhou 350108China Hefei National laboratory Hefei 230088China

Spontaneous symmetry breaking(SSB)plays a central role in understanding a large variety of phenomena associated with phase transitions,such as superfluid and superconductivity.So far,the transition from a symmetric vacuum to a macroscopically ordered phase has been substantially explored.The process bridging these two distinct phases is critical to understanding how a classical world emerges from a quantum phase transition,but so far remains unexplored in experiment.We here report an experimental demonstration of such a process with a quantum Rabi model engineered with a superconducting circuit.We move the system from the normal phase to the superradiant phase featuring two symmetry-breaking field components,one of which is observed to emerge as the classical reality.The results demonstrate that the environment-induced decoherence plays a critical role in the SSB.

关键词： quantum phase transition Rabi model spontaneous symmetry breaking superconducting circuit Schrodinger cat states

quantum key distribution over a mimicked dynamic-scattering channel

在线全文

学校读者我要写书评

暂无评论

Science China(information Sciences) 2024年第4期67卷 323-330页

作者： Qi-Hang LU Fang-Xiang WANG Wei CHEN Hai-Yang FU Yin-Jie LU Shuang WANG De-Yong HE Zhen-Qiang YIN Guang-Can GUO Zheng-Fu HAN CAS Key laboratory of quantum information University of Science and Technology of China CAS Center for Excellence in quantum information and quantum Physics University of Science and Technology of China Hefei National laboratory University of Science and Technology of China

Free-space quantum key distribution(QKD) plays an important role in the global quantum network. However, free space channels suffer from the atmospheric turbulence and scattering effects of haze,fog, and dust, which significantly weaken the performance of QKD or even block the secure quantum link.Here, we prove the performance of QKD over a dynamic scattering channel can be enhanced significantly using a fast wavefront shaping technique. The system achieves on average 10-dB enhancement of quantum transmission efficiency and establishes a secure quantum link for QKD. Our work demonstrates the feasibility of QKD through free-space dynamic scattering channels and enhances the deployment capability of complex-channel QKD system.

关键词： quantum key distribution free space channel channel turbulence channel scattering wavefront shaping

Measuring small longitudinal phase shifts via weak measurement amplification

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第3期33卷 105-111页

作者：徐凯胡晓敏胡孟军王宁宁张超黄运锋柳必恒李传锋郭光灿张永生 CAS Key laboratory of quantum information University of Science and Technology of ChinaHefei 230026China CAS Center For Excellence in quantum information and quantum Physics University of Science and Technology of ChinaHefei 230026China Hefei National laboratory University of Science and Technology of ChinaHefei 230088China Beijing Academy of quantum information Sciences Beijing 100193China

Weak measurement amplification,which is considered as a very promising scheme in precision measurement,has been applied to various small physical quantities estimations.Since many physical quantities can be converted into phase signals,it is interesting and important to consider measuring small longitudinal phase shifts by using weak measurement.Here,we propose and experimentally demonstrate a novel weak measurement amplification-based small longitudinal phase estimation,which is suitable for polarization interferometry.We realize one order of magnitude amplification measurement of a small phase signal directly introduced by a liquid crystal variable retarder and show that it is robust to the imperfection of interference.Besides,we analyze the effect of magnification error which is never considered in the previous works,and find the constraint on the magnification.Our results may find important applications in high-precision measurements,e.g.,gravitational wave detection.

关键词： weak measurement phase estimation quantum optics

Stimulated Brillouin interaction between guided phonons and photons in a lithium niobate waveguide

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2024年第1期67卷 173-175页

作者： Yuan-Hao Yang Jia-Qi Wang Zheng-Xu Zhu Xin-Biao Xu Qiang Zhang Juanjuan Lu Yu Zeng Chun-Hua Dong Luyan Sun Guang-Can Guo Chang-Ling Zou CAS Key laboratory of quantum information University of Science and Technology of ChinaHefei 230026China CAS Center for Excellence in quantum information and quantum Physics University of Science and Technology of ChinaHefei 230026China Key laboratory of quantum Optics and quantum Optics Devices Institute of Opto-ElectronicsShanxi UniversityTaiyuan 030006China School of information Science and Technology ShanghaiTech UniversityShanghai 201210China Center for quantum information Institute for Interdisciplinary Information SciencesTsinghua UniversityBeijing 100084China

The Brillouin scattering is one of the strongest nonlinear optical effects in dielectrics[1].In particular,the backward Brillouin scattering(BBS)provides an efficient method to achieve low-noise optical gain for active photonics[2]and the coherent interconnects between 10 GHz phonons and photons[3].However,previous studies on BBS are primarily limited to the unconfined phonons[1]or phonon confined in suspended structures[4-6].

关键词： scattering waveguide Brillouin

quantum nonlocality evolution for two entangled mesoscopic fields under decoherence

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2024年第1期76卷 24-28页

作者： Zhao-Song Tan Shou-Bang Yang Zhen-Biao Yang Shi-Biao Zheng Fujian Key laboratory of quantum information and quantum Optics Fuzhou UniversityFuzhouFujian 350116China

Investigation of the nonlocality evolution of entangled mesoscopic fields under decoherence not only is important for understanding the quantum–classical transition,but also has relevance to quantum communication and quantum computation protocols based on continuous variables.According to previous formulations of Bell inequalities,the system loses nonlocal features far before the disappearance of entanglement.We here construct a new version of Bell signal based on rotated and displaced on–off correlations,with which the Bell inequality is violated as long as there remains entanglement and the field state components keep quasiorthogonal.Consequently,the nonlocal character revealed by our formulation decays much slower compared with those based on previous ones.More importantly,there exists a wide regime where the Bell inequality is restored with previous formulations but remains to be violated based on our correlation operators.

关键词： entangled mesoscopic fields rotated and displaced on-off correlations Bell inequality nonlocality evolution

Proposal for sequential Stern-Gerlach experiment with programmable quantum processors

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第2期33卷 131-136页

作者：胡孟军缪海兴张永生 Beijing Academy of quantum information Sciences Beijing 100193China State Key laboratory of Low Dimensional quantum Physics Department of PhysicsTsinghua UniversityBeijing 100084China laboratory of quantum information University of Science and Technology of ChinaHefei 230026China Synergetic Innovation Center of quantum information and quantum Physics University of Science and Technology of ChinaHefei 230026China Hefei National laboratory University of Science and Technology of ChinaHefei 230088China

The historical significance of the Stern–Gerlach(SG)experiment lies in its provision of the initial evidence for space quantization.Over time,its sequential form has evolved into an elegant paradigm that effectively illustrates the fundamental principles of quantum theory.To date,the practical implementation of the sequential SG experiment has not been fully achieved.In this study,we demonstrate the capability of programmable quantum processors to simulate the sequential SG experiment.The specific parametric shallow quantum circuits,which are suitable for the limitations of current noisy quantum hardware,are given to replicate the functionality of SG devices with the ability to perform measurements in different directions.Surprisingly,it has been demonstrated that Wigner’s SG interferometer can be readily implemented in our sequential quantum circuit.With the utilization of the identical circuits,it is also feasible to implement Wheeler’s delayed-choice experiment.We propose the utilization of cross-shaped programmable quantum processors to showcase sequential experiments,and the simulation results demonstrate a strong alignment with theoretical predictions.With the rapid advancement of cloud-based quantum computing,such as BAQIS Quafu,it is our belief that the proposed solution is well-suited for deployment on the cloud,allowing for public accessibility.Our findings not only expand the potential applications of quantum computers,but also contribute to a deeper comprehension of the fundamental principles underlying quantum theory.

关键词： sequential Stern-Gerlach quantum circuit quantum processor

Maxwell Demon and Einstein–Podolsky–Rosen Steering

在线全文

学校读者我要写书评

暂无评论

Chinese Physics Letters 2024年第5期41卷 12-16页

作者：胡孟军胡晓敏张永生 Beijing Academy of quantum information Sciences Beijing 100193China laboratory of quantum information University of Science and Technology of ChinaHefei 230026China Synergetic Innovation Center of quantum information and quantum Physics University of Science and Technology of ChinaHefei 230026China Hefei National laboratory University of Science and Technology of ChinaHefei 230088China

Research of Maxwell demon and quantum entanglement is important because of its foundational significance in physics and its potential applications in quantum information. Previous studies on the Maxwell demon have primarily focused on thermodynamics, taking into account quantum correlations. Here we consider from another perspective and ask whether quantum non-locality correlations can be simulated by performing work. The Maxwell demon-assisted Einstein–Podolsky–Rosen(EPR) steering is thus proposed, which implies a new type of loophole. The application of Landauer's erasure principle suggests that the only way to close this loophole during a steering task is by continuously monitoring the heat fluctuation of the local environment by the participant.We construct a quantum circuit model of Maxwell demon-assisted EPR steering, which can be demonstrated by current programmable quantum processors, such as superconducting quantum computers. Based on this quantum circuit model, we obtain a quantitative formula describing the relationship between energy dissipation due to the work of the demon and quantum non-locality correlation. The result is of great physical interest because it provides a new way to explore and understand the relationship between quantum non-locality, information, and thermodynamics.

关键词： quantum Maxwell Einstein

General Method of Combining Grover and Simon for Attacking Block Ciphers

在线全文

学校读者我要写书评

暂无评论

China Communications 2024年第6期21卷 237-245页

作者： Fu Xiangqun Bao Wansu Shi Jianhong Li Tan Henan Key laboratory of quantum information and Cryptography PLA SSF IEUZhengzhou 450001China Synergetic Innovation Center of quantum information and quantum Physics University of Science and Technology of ChinaHefei 230026China

The compatibility of different quantum algorithms should be considered when these algorithms are combined.In this paper,the method of combining Grover and Simon is studied for the first time,under some preconditions or assumptions.First,we give two preconditions of applying Grover’s algorithm,which ensure that the success probability of finding the marked element is close to 1.Then,based on these two preconditions,it is found out that the success probability of the quantum algorithm for FXconstruction is far less than 1.Furthermore,we give the design method of the Oracle function,and then present the general method of combining Grover and Simon algorithm for attacking block ciphers,with success probability close to 1.

关键词： block ciphers post-quantum crypto quantum algorithms

Quantized anomalous Hall resistivity achieved in molecular beam epitaxy-grown Mn Bi2Te4 thin films

在线全文

学校读者我要写书评

暂无评论

National Science Review 2024年第2期11卷 24-32页

作者： Yunhe Bai Yuanzhao Li Jianli Luan Ruixuan Liu Wenyu Song Yang Chen Peng-Fei Ji Qinghua Zhang Fanqi Meng Bingbing Tong Lin Li Yuying Jiang Zongwei Gao Lin Gu Jinsong Zhang Yayu Wang Qi-Kun Xue Ke He Yang Feng Xiao Feng State Key laboratory of Low Dimensional quantum Physics Department of Physics Tsinghua University Institute of Physics Chinese Academy of Sciences School of Materials Science and Engineering Tsinghua University Beijing Academy of quantum information Sciences Frontier Science Center for quantum information Hefei National laboratory Southern University of Science and Technology

The intrinsic magnetic topological insulator MnBi2Te4provides a feasible pathway to the high-temperature quantum anomalous Hall（QAH） effect as well as various novel topological quantum phases. Although quantized transport properties have been observed in exfoliated MnBi2Te4thin flakes, it remains a big challenge to achieve molecular beam epitaxy（MBE）-grown MnBi2Te4thin films even close to the quantized regime. In this work, we report the realization of quantized anomalous Hall resistivity in MBE-grown MnBi2Te4thin films with the chemical potential tuned by both controlled in situ oxygen exposure and top gating. We find that elongated post-annealing obviously elevates the temperature to achieve quantization of the Hall resistivity, but also increases the residual longitudinal resistivity, indicating a picture of high-quality QAH puddles weakly coupled by tunnel barriers. These results help to clarify the puzzles in previous experimental studies on MnBi2Te4and to find a way out of the big difficulty in obtaining MnBi2Te4samples showing quantized transport properties.

关键词： intrinsic magnetic topological insulator quantized anomalous Hall resistivity molecular beam epitaxy quantized transport property