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arXiv 2024年

作者： Wang, Yu-Tong Ye, Qi-Hang Yan, Jun-Yong Qiao, Yufei Chen, Chen Cheng, Xiao-Tian Li, Chen-Hui Zhang, Zi-Jian Huang, Cheng-Nian Meng, Yun Zou, Kai Zhan, Wen-Kang Zhao, Chao Hu, Xiaolong Tee, Clarence Augustine T.H. Sha, Wei E.I. Huang, Zhixiang Liu, Huiyun Jin, Chao-Yuan Ying, Lei Liu, Feng State Key Laboratory of Extreme Photonics and Instrumentation College of Information Science and Electronic Engineering Zhejiang University Hangzhou310027 China School of Physics Zhejiang Key Laboratory of Micro-nano Quantum Chips and Quantum Control Zhejiang University Hangzhou310027 China School of Precision Instrument and Optoelectronic Engineering Tianjin University Tianjin300072 China Key Laboratory of Optoelectronic Information Science and Technology Ministry of Education Tianjin300072 China Laboratory of Solid State Optoelectronics Information Technology Institute of Semiconductors Chinese Academy of Sciences Beijing100083 China College of Materials Science and Opto-Electronic Technology University of Chinese Academy of Science Beijing101804 China College of Physics and Electrical Information Engineering Zhejiang Normal University Hangzhou310058 China Key Laboratory of Intelligent Computing and Signal Processing Ministry of Education Anhui University Hefei230039 China Department of Electronic and Electrical Engineering University College London LondonWC1E 7JE United Kingdom International Joint Innovation Center Zhejiang University Haining314400 China

quantum emitters are a key component in photonic quantum technologies. Enhancing their single-photon emission by engineering the photonic environment using cavities can improve the overall efficiency in quantum information processing. However, this enhancement is often limited by the need for precise nanoscale control over emitter’s position within micro/nano-cavities. Inspired by the fascinated physics of moiré pattern, we present an approach to strongly modify the spontaneous emission rate of a quantum emitter using fine-designed multilayer moiré photonic crystal with a robust isolate-flatband dispersion. Theoretical analysis reveals that due to its nearly infinite photonic density of states, the moiré cavity can simultaneously possess high Purcell factor and large tolerance over emitter’s position. We experimentally demonstrate the coupling between this moiré cavity and a quantum dot via the cavity-determined polarization of the dot’s emission. The radiative lifetime of the quantum dot can be tuned by a factor of 40 from 42 ps to 1692 ps, attributed to strong Purcell enhancement and Purcell inhibition effects. Our findings pave the way for moiré flatband cavity-enhanced quantum light sources, quantum optical switches and quantum nodes for quantum internet. Copyright © 2024, The Authors. All rights reserved.

关键词： Particle beams

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Characterisation of state-preparation uncertainty in quantum key distribution

arXiv

引用

arXiv 2022年

作者： Huang, Anqi Mizutani, Akihiro Lo, Hoi-Kwong Makarov, Vadim Tamaki, Kiyoshi Institute for Quantum Information State Key Laboratory of High Performance Computing College of Computer Science and Technology National University of Defense Technology Changsha410073 China Graduate School of Engineering Science Osaka University Toyonaka Osaka560-8531 Japan Department of Electrical & Computer Engineering Department of Physics University of Toronto TorontoONM5S 3G4 Canada Department of Physics University of Hong Kong Pokfulam Hong Kong Quantum Bridge Technologies Inc. 100 College Street TorontoONM5G 1L5 Canada Russian Quantum Center Skolkovo Moscow121205 Russia Shanghai Branch National Laboratory for Physical Sciences at Microscale and CAS Center for Excellence in Quantum Information University of Science and Technology of China Shanghai201315 China NTI Center for Quantum Communications National University of Science and Technology MISiS Moscow119049 Russia Faculty of Engineering University of Toyama Gofuku 3190 Toyama930-8555 Japan

To achieve secure quantum key distribution, all imperfections in the source unit must be incorporated in a security proof and measured in the lab. Here we perform a proof-of-principle demonstration of the experimental techniques for characterising the source phase and intensity fluctuation in commercial quantum key distribution systems. When we apply the measured phase fluctuation intervals to the security proof that takes into account fluctuations in the state preparation, it predicts a key distribution distance of over 100 km of fiber. The measured intensity fluctuation intervals are however so large that the proof predicts zero key, indicating a source improvement may be needed. Our characterisation methods pave the way for a future certification standard. Copyright © 2022, The Authors. All rights reserved.

关键词： quantum cryptography

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Streaming quantum state purification

arXiv

引用

arXiv 2023年

作者： Childs, Andrew M. Fu, Honghao Leung, Debbie Li, Zhi Ozols, Maris Vyas, Vedang Institute for Quantum Computing University of Waterloo WaterlooONN2L 3G1 Canada Department of Computer Science Institute for Advanced Computer Studies Joint Center for Quantum Information and Computer Science University of Maryland College ParkMD20742 United States Massachusetts Institute of Technology 77 Massachusetts Ave. CambridgeMA02139 United States Perimeter Institute for Theoretical Physics 31 Caroline St. N. WaterlooONN2L 2Y5 Canada QuSoft University of Amsterdam Science Park 123 Amsterdam1098 XG Netherlands Concordia Institute of Information Systems Engineering Concordia University 1455 Blvd. De Maisonneuve Ouest MontrealQCH3G 1M8 Canada

quantum state purification is the task of recovering a nearly pure copy of an unknown pure quantum state using multiple noisy copies of the state. This basic task has applications to quantum communication over noisy channels and quantum computation with imperfect devices, but has primarily been studied previously for the case of qubits. We derive an efficient purification procedure based on the swap test for qudits of any dimension, starting with any initial error parameter. Treating the initial error parameter and the dimension as constants, we show that our procedure has sample complexity asymptotically optimal in the final error parameter. Our protocol has a simple recursive structure that can be applied when the states are provided one at a time in a streaming fashion, requiring only a small quantum memory to implement. © 2023, CC BY.

关键词： quantum communication

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Antisymmetric planar Hall effect in rutile oxide films induced by the Lorentz force

arXiv

引用

arXiv 2023年

作者： Cui, Yongwei Li, Zhaoqing Chen, Haoran Wu, Yunzhuo Chen, Yue Pei, Ke Wu, Tong Xie, Nian Che, Renchao Qiu, Xuepeng Liu, Yi Yuan, Zhe Wu, Yizheng Department of Physics State Key Laboratory of Surface Physics Fudan University Shanghai200433 China Institute for Nanoelectronic Devices and Quantum Computing Fudan University Shanghai200433 China Interdisciplinary Center for Theoretical Physics and Information Sciences Fudan University Shanghai200433 China Center for Advanced Quantum Studies Department of Physics Beijing Normal University Beijing100875 China Laboratory of Advanced Materials Shanghai Key Lab of Molecular Catalysis and Innovative Materials Academy for Engineering & Technology Fudan University Shanghai200438 China Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology School of Physics Science and Engineering Tongji University Shanghai200092 China Zhejiang Laboratory Hangzhou311100 China Shanghai Research Center for Quantum Sciences Shanghai201315 China Shanghai Key Laboratory of Metasurfaces for Light Manipulation Fudan University Shanghai200433 China

The conventional Hall effect is linearly proportional to the field component or magnetization component perpendicular to a film [1]. Despite the increasing theoretical proposals on the Hall effect to the in-plane field or magnetization in various special systems induced by the Berry curvature [2-8], such an unconventional Hall effect has only been experimentally reported in Weyl semimetals and in a heterodimensional superlattice [9-12]. Here, we report an unambiguous experimental observation of the antisymmetric planar Hall effect (APHE) with respect to the in-plane magnetic field in centrosymmetric rutile RuO2 and IrO2 single-crystal films. The measured Hall resistivity is found to be linearly proportional to the component of the applied in-plane magnetic field along a particular crystal axis and to be independent of the current direction or temperature. Both the experimental observations and theoretical calculations confirm that the APHE in rutile oxide films is induced by the Lorentz force. Our findings can be generalized to ferromagnetic materials for the discovery of anomalous Hall effects and quantum anomalous Hall effects induced by in-plane magnetization. In addition to significantly expanding knowledge of the Hall effect, this work opens the door to explore new members in the Hall effect family. Copyright © 2023, The Authors. All rights reserved.

关键词： Crystal symmetry

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Modeling Neural Networks Training Process with Markov Decision Process

Modeling Neural Networks Training Process with Markov Decisi...

引用

Artificial Intelligence and Computer engineering (ICAICE), International Conference on

作者： Yantao Bai Wanwei Liu Xinjun Mao Zhen Liang Key Laboratory of Software Engineering for Complex Systems National University of Defense Technology Changsha China College of Computer Science National University of Defense Technology Changsha China State Key Laboratory of High Performance Computing Institute for Quantum Information &#x0026 National University of Defense Technology Changsha China

ISBN: (纸本)9781665421874

With the development of computer technology, statistics-based machine learning method has made great break-throughs, and also improved the development of artificial intelligence. Nevertheless, as a very influential model, neural networks are still treated as “black boxes”. The results of neural networks are extremely sensitive to the training samples, which lead to great challenges to the controllability of the algorithm. With the wide application of machine learning, demand for interpretability and controllability of neural networks algorithms is increasing. As a result, various scholars have tried to explain and verify neural networks algorithms based on formal methods in recent years. In this paper, a method (called MNNTP) is presented to model the training process of neural networks by using a Markov decision process (MDP). Through MNNTP, the neural networks are abstracted into the form of MDP, which makes notable contributions for verifying some mathematical properties of the neural networks.

关键词： Training Machine learning algorithms Computational modeling Neural networks Machine learning Markov processes Controllability

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CompressedMediQ: Hybrid quantum Machine Learning Pipeline for High-Dimensional Neuroimaging Data

CompressedMediQ: Hybrid Quantum Machine Learning Pipeline fo...

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Acoustics, Speech, and Signal Processing Workshops (ICASSPW), IEEE International Conference on

作者： Kuan-Cheng Chen Yi-Tien Li Tai-Yu Li Chen-Yu Liu Po-Heng Henry Lee Cheng-Yu Chen Department of Electrical and Electronic Engineering Imperial College London London UK Centre for Quantum Engineering Science and Technology (QuEST) Imperial College London London UK Translational Imaging Research Center Taipei Medical University Hospital Taipei Taiwan Research Center for Neuroscience Taipei Medical University Taipei Taiwan Ph.D. Program in Medical Neuroscience College of Medical Science and Technology Taipei Medical University Taipei Taiwan National Center for High-Performance Computing NARlabs Hsinchu Taiwan Graduate Institute of Applied Physics National Taiwan University Taipei Taiwan Department of Medical Imaging Taipei Medical University Hospital Taipei Taiwan Department of Radiology National Defense Medical Center Taipei Taiwan Department of Radiology School of Medicine College of Medicine Taipei Taiwan

ISBN: (数字)9798331519315

ISBN: (纸本)9798331519322

This paper introduces CompressedMediQ, a novel hybrid quantum-classical machine learning pipeline specifically developed to address the computational challenges associated with high-dimensional multi-class neuroimaging data analysis. Standard neuroimaging datasets, such as large-scale MRI data from the Alzheimer’s Disease Neuroimaging Initiative and Neuroimaging in Frontotemporal Dementia, present significant hurdles due to their vast size and complexity. CompressedMediQ integrates classical HPC nodes for advanced MRI pre-processing and Convolutional Neural Network (CNN)-PCA-based feature extraction and reduction, addressing the limited-qubit availability for quantum data encoding in the NISQ era. This is followed by quantum Support Vector Machine (QSVM) classification. By utilizing quantum kernel methods, the pipeline optimizes feature mapping and classification, enhancing data separability and outperforming traditional neuroimaging analysis techniques. Experimental results highlight the pipeline’s superior accuracy in dementia staging, validating the practical use of quantum machine learning in clinical diagnostics. Despite the limitations of NISQ devices, this proof-of-concept demonstrates the transformative potential of quantum-enhanced learning, paving the way for scalable and precise diagnostic tools in healthcare and signal processing.

关键词： Neuroimaging Support vector machines quantum computing Accuracy Magnetic resonance imaging Pipelines Machine learning Medical services Signal processing Standards

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Hamiltonian Phase Error in Resonantly Driven CNOT Gate Above the Fault-Tolerant Threshold

arXiv

引用

arXiv 2023年

作者： Wu, Yi-Hsien Camenzind, Leon C. Noiri, Akito Takeda, Kenta Nakajima, Takashi Kobayashi, Takashi Chang, Chien-Yuan Sammak, Amir Scappucci, Giordano Goan, Hsi-Sheng Tarucha, Seigo Department of Physics National Taiwan University Taipei10617 Taiwan Center for Emergent Matter Science RIKEN 2-1 Hirosawa Saitama Wako-shi351-0198 Japan Center for Quantum Computing RIKEN 2-1 Hirosawa Saitama Wako-shi351-0198 Japan Stieltjesweg 1 Delft2628 CK Netherlands QuTech and Kavli Institute of Nanoscience Delft University of Technology PO Box 5046 Delft2600 GA Netherlands Center of Quantum Science and Engineering National Taiwan University Taipei10617 Taiwan Physics Division National Center for Theoretical Sciences Taipei10617 Taiwan

Because of their long coherence time and compatibility with industrial foundry processes, electron spin qubits are a promising platform for scalable quantum processors. A full-fledged quantum computer will need quantum error correction, which requires high-fidelity quantum gates. Analyzing and mitigating the gate errors are useful to improve the gate fidelity. Here, we demonstrate a simple yet reliable calibration procedure for a high-fidelity controlled-rotation gate in an exchange-always-on Silicon quantum processor allowing operation above the fault-tolerance threshold of quantum error correction. We find that the fidelity of our uncalibrated controlled-rotation gate is limited by coherent errors in the form of controlled-phases and present a method to measure and correct these phase errors. We then verify the improvement in our gate fidelities by randomized benchmark and gate-set tomography protocols. Finally, we use our phase correction protocol to implement a virtual, high-fidelity controlled-phase gate. Copyright © 2023, The Authors. All rights reserved.

关键词： Magnetic moments

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Torque-induced dispersive readout in a weakly coupled hybrid system

arXiv

引用

arXiv 2020年

作者： Grigoryan, Vahram L. Xia, Ke Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen518055 China Center for Quantum Computing Peng Cheng Laboratory Shenzhen518005 China

We propose a quantum state readout mechanism of a weakly coupled qubit in dispersive regime. The hybrid system consists of ferromagnetic insulator and a superconducting qubit in a microwave cavity. The enhancement of the measurement sensitivity is achieved by exerting torque on the ferromagnetic insulator magnetization, which compensates the damping of the system leading to an exceptional point. The proposed machanism allows to measure the qubit state either via the transmission of the cavity or the FMR signal of the magnetic material. Copyright © 2020, The Authors. All rights reserved.

关键词： Hybrid systems

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Extrinsic nonlinear Kerr rotation in topological materials under a magnetic field

arXiv

引用

arXiv 2023年

作者： Wu, Shuang Fei, Zaiyao Sun, Zeyuan Yi, Yangfan Xia, Wei Yan, Dayu Guo, Yanfeng Shi, Youguo Yan, Jiaqiang Cobden, David H. Liu, Wei-Tao Xu, Xiaodong Wu, Shiwei Department of Physics Fudan University Shanghai200433 China Department of Physics University of Washington SeattleWA98195 United States School of Physical Science and Technology ShanghaiTech Laboratory for Topological Physics ShanghaiTech University Shanghai201210 China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing100190 China Materials Science and Technology Division Oak Ridge National Laboratory Oak RidgeTN37831 United States Department of Materials Science and Engineering University of Washington SeattleWA98195 United States Shanghai Qi Zhi Institute Shanghai200232 China Institute for Nanoelectronic Devices and Quantum Computing Zhangjiang Fudan International Innovation Center Fudan University Shanghai200433 China Shanghai Research Center for Quantum Sciences Shanghai201315 China

Topological properties in quantum materials are often governed by symmetry and tuned by crystal structure and external fields, and hence symmetry-sensitive nonlinear optical measurements in a magnetic field are a valuable probe. Here we report nonlinear magneto-optical second harmonic generation (SHG) studies of non-magnetic topological materials including bilayer WTe2, monolayer WSe2 and bulk TaAs. The polarization-resolved patterns of optical SHG under magnetic field show nonlinear Kerr rotation in these time-reversal symmetric materials. For materials with three-fold rotational symmetric lattice structure, the SHG polarization pattern rotates just slightly in a magnetic field, whereas in those with mirror or two-fold rotational symmetry the SHG polarization pattern rotates greatly and distorts. These different magneto-SHG characters can be understood by considering the superposition of the magnetic field-induced time-noninvariant nonlinear optical tensor and the crystal-structure-based time-invariant counterpart. The situation is further clarified by scrutinizing the Faraday rotation, whose subtle interplay with crystal symmetry accounts for the diverse behavior of the extrinsic nonlinear Kerr rotation in different materials. Our work illustrates the application of magneto-SHG techniques to directly probe nontrivial topological properties, and underlines the importance of minimizing extrinsic nonlinear Kerr rotation in polarization-resolved magneto-optical studies. © 2023, CC BY.

关键词： Harmonic generation

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Microwave amplification via interfering multi-photon processes in a half-waveguide quantum electrodynamics system

arXiv

引用

arXiv 2023年

作者： Aziz, Fahad Lin, Kuan Ting Wen, Ping Yi Samina Lin, Yu Chen Wiegand, Emely Lee, Ching-Ping Cheng, Yu-Ting Chen, Ching-Yeh Chien, Chin-Hsun Hsieh, Kai-Min Huang, Yu-Huan Hou, Ian Chen, Jeng-Chung Lin, Yen-Hsiang Kockum, Anton Frisk Lin, Guin Dar Hoi, Io-Chun Department of Physics National Tsing Hua University Hsinchu30013 Taiwan Department of Physics CQSE National Taiwan University Taipei10617 Taiwan Department of Physics National Chung Cheng University Chiayi621301 Taiwan Department of Microtechnology and Nanoscience Chalmers University of Technology Gothenburg412 96 Sweden Institute of Applied Physics and Materials Engineering University of Macau Macau China UMacau Zhuhai Research Institute Guangdong Zhuhai China Center for Quantum Technology National Tsing Hua University Hsinchu30013 Taiwan Physics Division National Center for Theoretical Sciences Taipei10617 Taiwan Trapped-Ion Quantum Computing Laboratory Hon Hai Research Institute Taipei11492 Taiwan Department of Physics City University of Hong Kong Tat Chee Avenue Kowloon999077 Hong Kong

We investigate the amplification of a microwave probe signal by a superconducting artificial atom, a transmon, strongly coupled to the end of a one-dimensional semi-infinite transmission line. The end of the transmission line acts as a mirror for microwave fields. Due to the weak anharmonicity of the artificial atom, a strong pump field creates multi-photon excitations among the dressed states. Transitions between these dressed states, Rabi sidebands, give rise to either amplification or attenuation of the weak probe. We obtain a maximum amplitude amplification of about 18 %, higher than in any previous experiment with a single artificial atom, due to constructive interference between Rabi sidebands. We also characterize the noise properties of the system by measuring the spectrum of spontaneous emission. Copyright © 2023, The Authors. All rights reserved.

关键词： Amplification

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