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Photoionisation detection of a single Er3+ ion with sub-100-ns time resolution

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National Science Review 2024年第4期11卷 38-45页

作者： Yangbo Zhang Wenda Fan Jiliang Yang Hao Guan Qi Zhang Xi Qin Changkui Duan Gabriele G.de Boo Brett C.Johnson Jeffrey C.Mc Callum Matthew J.Sellars Sven Rogge Chunming Yin Jiangfeng Du CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences 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 Centre of Excellence for quantum computation and Communication Technology School of Physics University of New South Wales Centre of Excellence for quantum computation and Communication Technology School of Engineering RMIT University Centre of Excellence for quantum computation and Communication Technology School of Physics University of Melbourne Centre of Excellence for quantum computation and Communication Technology Research School of Physics and Engineering Australian National University

Efficient detection of single optical centres in solids is essential for quantum information processing, sensing and single-photon generation *** this work,we use radio-frequency（RF） reflectometry to electrically detect the photoionisation induced by a single Er3+ion in *** high bandwidth and sensitivity of the RF reflectometry provide sub-100-ns time resolution for the photoionisation *** this technique,the optically excited state lifetime of a single Er3+ion in a Si nano-transistor is measured for the first time to be 0.49±0.04μ*** results demonstrate an efficient approach for detecting a charge state change induced by Er excitation and *** approach could be used for fast readout of other single optical centres in solids and is attractive for large-scale integrated optical quantum systems thanks to the multi-channel RF reflectometry demonstrated with frequency multiplexing techniques.

关键词： single optical centres erbium ions RF reflectometry photoionisation detection

Quafu-Qcover:Explore combinatorial optimization problems on cloud-based quantum computers

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Chinese Physics B 2024年第5期33卷 104-115页

作者：许宏泽庄伟峰王正安黄凯旋时运豪马卫国李天铭陈驰通许凯冯玉龙刘培陈墨李尚书杨智鹏钱辰靳羽欣马运恒肖骁钱鹏顾炎武柴绪丹普亚南张翼鹏魏世杰增进峰李行龙桂鲁金贻荣于海峰范桁刘东胡孟军 Beijing Academy of quantum information Sciences Beijing 100193China State Key Laboratory of Low Dimensional quantum Physics Department of PhysicsTsinghua UniversityBeijing 100084China Institute of Physics Chinese Academy of SciencesBeijing 100190China Frontier Science Center for quantum information Beijing 100184China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100190China CAS Center for Excellence in Topological quantum computation UCASBeijing 100190China

We introduce Quafu-Qcover,an open-source cloud-based software package developed for solving combinatorial optimization problems using quantum simulators and hardware ***-Qcover provides a standardized and comprehensive workflow that utilizes the quantum approximate optimization algorithm(QAOA).It facilitates the automatic conversion of the original problem into a quadratic unconstrained binary optimization(QUBO)model and its corresponding Ising model,which can be subsequently transformed into a weight *** core of Qcover relies on a graph decomposition-based classical algorithm,which efficiently derives the optimal parameters for the shallow QAOA ***-Qcover incorporates a dedicated compiler capable of translating QAOA circuits into physical quantum circuits that can be executed on Quafu cloud quantum *** to a general-purpose compiler,our compiler demonstrates the ability to generate shorter circuit depths,while also exhibiting superior speed ***,the Qcover compiler has the capability to dynamically create a library of qubits coupling substructures in real-time,utilizing the most recent calibration data from the superconducting quantum *** ensures that computational tasks can be assigned to connected physical qubits with the highest *** Quafu-Qcover allows us to retrieve quantum computing sampling results using a task ID at any time,enabling asynchronous ***,it incorporates modules for results preprocessing and visualization,facilitating an intuitive display of solutions for combinatorial optimization *** hope that Quafu-Qcover can serve as an instructive illustration for how to explore application problems on the Quafu cloud quantum computers.

关键词： quantum cloud platform combinatorial optimization problems quantum software

Layer Hall effect induced by hidden Berry curvature in antiferromagnetic insulators

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National Science Review 2024年第2期11卷 15-23页

作者： Rui Chen Hai-Peng Sun Mingqiang Gu Chun-Bo Hua Qihang Liu Hai-Zhou Lu X.C.Xie Shenzhen Institute for quantum Science and Engineering and Department of Physics Southern University of Science and Technology(SUSTech) International quantum Academy Institute for Theoretical Physics and Astrophysics University of Würzburg School of Electronic and information Engineering Hubei University of Science and Technology Guangdong Provincial Key Laboratory of computational Science and Material Design Southern University of Science and Technology Shenzhen Key Laboratory of quantum Science and Engineering International Center for quantum Materials School of PhysicsPeking University Collaborative Innovation Center of quantum Matter CAS Center for Excellence in Topological quantum computation University of Chinese Academy of Sciences

The layer Hall effect describes electrons spontaneously deflected to opposite sides at different layers, which has been experimentally reported in the MnBi2Te4thin films under perpendicular electric fields. Here, we reveal a universal origin of the layer Hall effect in terms of the so-called hidden Berry curvature, as well as material design principles. Hence, it gives rise to zero Berry curvature in momentum space but non-zero layer-locked hidden Berry curvature in real space. We show that, compared to that of a trivial insulator, the layer Hall effect is significantly enhanced in antiferromagnetic topological insulators. Our universal picture provides a paradigm for revealing the hidden physics as a result of the interplay between the global and local symmetries, and can be generalized in various scenarios.

关键词： layerHall effect hidden Berry curvature antiferromagnetic insulator axion insulator, quantum transport

quantum nonlocality evolution for two entangled mesoscopic fields under decoherence

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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 *** to previous formulations of Bell inequalities,the system loses nonlocal features far before the disappearance of *** 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 ***,the nonlocal character revealed by our formulation decays much slower compared with those based on previous *** 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

Quafu-RL:The cloud quantum computers based quantum reinforcement learning

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Chinese Physics B 2024年第5期33卷 29-34页

作者：靳羽欣许宏泽王正安庄伟峰黄凯旋时运豪马卫国李天铭陈驰通许凯冯玉龙刘培陈墨李尚书杨智鹏钱辰马运恒肖骁钱鹏顾炎武柴绪丹普亚南张翼鹏魏世杰曾进峰李行龙桂鲁金贻荣于海峰范桁刘东胡孟军 Beijing Academy of quantum information Sciences Beijing 100193China State Key Laboratory of Low Dimensional quantum Physics Department of PhysicsTsinghua UniversityBeijing 100084China Institute of Physics Chinese Academy of SciencesBeijing 100190China Frontier Science Center for quantum information Beijing 100184China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100190China CAS Center for Excellence in Topological quantum computation University of Chinese Academy of SciencesBeijing 100190China School of Mathematical Sciences Nankai UniversityTianjin 300071China

With the rapid advancement of quantum computing,hybrid quantum–classical machine learning has shown numerous potential applications at the current stage,with expectations of being achievable in the noisy intermediate-scale quantum(NISQ)*** reinforcement learning,as an indispensable study,has recently demonstrated its ability to solve standard benchmark environments with formally provable theoretical advantages over classical ***,despite the progress of quantum processors and the emergence of quantum computing clouds,implementing quantum reinforcement learning algorithms utilizing parameterized quantum circuits(PQCs)on NISQ devices remains *** this work,we take the first step towards executing benchmark quantum reinforcement problems on real devices equipped with at most 136 qubits on the BAQIS Quafu quantum computing *** experimental results demonstrate that the policy agents can successfully accomplish objectives under modified conditions in both the training and inference ***,we design hardware-efficient PQC architectures in the quantum model using a multi-objective evolutionary algorithm and develop a learning algorithm that is adaptable to quantum *** hope that the Quafu-RL can be a guiding example to show how to realize machine learning tasks by taking advantage of quantum computers on the quantum cloud platform.

关键词： quantum cloud platform quantum reinforcement learning evolutionary quantum architecture search

A von-Neumann-like photonic processor and its application in studying quantum signature of chaos

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Light(Science & Applications) 2024年第4期13卷 672-681页

作者： Shang Yu Wei Liu Si-Jing Tao Zhi-Peng Li Yi-Tao Wang Zhi-Peng Zhong Raj BPatel Yu Meng Yuan-Ze Yang Zhao-An Wang Nai-Jie Guo Xiao-Dong Zeng Zhe Chen Liang Xu Ning Zhang Xiao Liu Mu Yang Wen-Hao Zhang Zong-Quan Zhou Jin-Shi Xu Jian-Shun Tang Yong-Jian Han Chuan-Feng Li Guang-Can Guo 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. Research Center for quantum Sensing Zhejiang LabHangzhou 310000China. quantum Optics and Laser Science Blackett LaboratoryImperial College LondonPrince Consort RdLondon SW72AZUK. Clarendon Laboratory Department of PhysicsOxford UniversityParks Road OX13PUOxfordUK

Photonic quantum computation plays an important role and offers unique *** decades after the milestone work of Knill-Laflamme-Milburn,various architectures of photonic processors have been proposed,and quantum advantage over classical computers has also been *** is now the opportune time to apply this technology to real-world ***,at current technology level,this aim is restricted by either programmability in bulk optics or loss in integrated optics for the existing architectures of processors,for which the resource cost is also a *** we present a von-Neumann-like architecture based on temporal-mode encoding and looped structure on table,which is capable of multimode-universal programmability,resource-efficiency,phasestability and *** order to illustrate these merits,we execute two different programs with varying resource requirements on the same processor,to investigate quantum signature of chaos from two aspects:the signature behaviors exhibited in phase space(13 modes),and the Fermi golden rule which has not been experimentally studied in quantitative way before(26 modes).The maximal program contains an optical interferometer network with 1694 freely-adjustable *** current state-of-the-art,our architecture stands as the most promising candidate for real-world applications.

关键词： quantum signature chaos

Simulations of superconducting quantum gates by digital flux tuner for qubits

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Chinese Physics B 2024年第7期33卷 210-222页

作者：耿霄何楷泳刘建设陈炜 Laboratory of Superconducting quantum information Processing School of Integrated CircuitsTsinghua UniversityBeijing 100084China Beijing Innovation Center for Future Chips Tsinghua UniversityBeijing 100084China Beijing National Research Center for information Science and Technology Beijing 100084China26

The interconnection bottleneck caused by limitations of cable number, inner space and cooling power of dilution refrigerators has been an outstanding challenge for building scalable superconducting quantum computers with the increasing number of qubits in quantum processors. To surmount such an obstacle, it is desirable to integrate qubits with quantum–classical interface(QCI) circuits based on rapid single flux quantum(RSFQ) circuits. In this work, a digital flux tuner for qubits(DFTQ) is proposed for manipulating flux of qubits as a crucial part of the interface circuit. A schematic diagram of the DFTQ is presented, consisting of a coarse tuning unit and a fine-tuning unit for providing magnetic flux with different precision to qubits. The method of using DFTQ to provide flux for gate operations is discussed from the optimization of circuit design and input signal. To verify the effectiveness of the method, simulations of a single DFTQ and quantum gates including a Z gate and an iSWAP gate with DFTQs are performed for flux-tunable transmons. The quantum process tomography corresponding to the two gates is also carried out to analyze the sources of gate error. The results of tomography show that the gate fidelities independent of the initial states of the Z gate and the iSWAP gate are 99.935% and 99.676%,respectively. With DFTQs inside, the QCI would be a powerful tool for building large-scale quantum computers.

关键词： quantum computation superconducting electronics quantum control

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量子极限下的能量耗散

Science Bulletin 2024年第9期69卷 1221-1227页

作者：李海龙江华孙庆丰谢心澄 International Center for quantum Materials School of PhysicsPeking UniversityBeijing 100871China Interdisciplinary Center for Theoretical Physics and information Sciences(ICTPIS) Fudan UniversityShanghai 200433China Institute for Nanoelectronic Devices and quantum Computing Fudan UniversityShanghai 200433China CAS Center for Excellence in Topological quantum computation University of Chinese Academy of SciencesBeijing 100190China Hefei National Laboratory Hefei 230088China

Energy dissipation is of fundamental interest and crucial importance in quantum systems. However,whether energy dissipation can emerge without backscattering inside topological systems remains a question. As a hallmark, we propose a microscopic picture that illustrates energy dissipation in the quantum Hall(QH) plateau regime of graphene. Despite the quantization of Hall, longitudinal, and two-probe resistances(dubbed as the quantum limit), we find that the energy dissipation emerges in the form of Joule heat. It is demonstrated that the non-equilibrium energy distribution of carriers plays much more essential roles than the resistance on energy dissipation. Eventually, we suggest probing the phenomenon by measuring local temperature increases in experiments and reconsidering the dissipation typically ignored in realistic topological circuits.

关键词： Energy dissipation Topological systems Non-equilibrium energy distribution Chern insulators quantum limit

Field induced Chern insulating states in twisted monolayer–bilayer graphene

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Chinese Physics B 2024年第6期33卷 69-73页

作者：王政文韩英卓 Kenji Watanabe Takashi Taniguchi 姜宇航毛金海 School of Physical Science and CAS Center for Excellence in Topological quantum computation University of Chinese Academy of SciencesBeijing 100049China College of Materials Science and Optoelectronic Technology Center of Materials Science and Optoelectronics EngineeringUniversity of Chinese Academy of SciencesBeijing 100049China Advanced Materials Laboratory National Institute for Materials ScienceTsukuba 305-0044Japan

Unraveling the mechanism underlying topological phases, notably the Chern insulators(Ch Is) in strong correlated systems at the microscopy scale, has captivated significant research interest. Nonetheless, Ch Is harboring topological information have not always manifested themselves, owing to the constraints imposed by displacement fields in certain experimental configurations. In this study, we employ density-tuned scanning tunneling microscopy(DT-STM) to investigate the Ch Is in twisted monolayer–bilayer graphene(t MBG). At zero magnetic field, we observe correlated metallic *** under a magnetic field, a metal–insulator transition happens and an integer Ch I is formed emanating from the filling index s = 3 with a Chern number C = 1. Our results underscore the pivotal role of magnetic fields as a powerful probe for elucidating topological phases in twisted Van der Waals heterostructures.

关键词： Chern insulators strong correlation effects two-dimensional van der Waals heterostructure density-tuned scanning tunneling microscopy(DT-STM)