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628 results on '"Kong, Xiang‐yu"'

4. Global Correlation and Local Information Flows in Controllable Non-Markovian Open Quantum Dynamics

Author

Chen, Xin-Yu, Zhang, Na-Na, He, Wan-Ting, Kong, Xiang-Yu, Tao, Ming-Jie, Deng, Fu-Guo, Ai, Qing, and Long, Gui-Lu

Subjects
Quantum Physics, Condensed Matter - Statistical Mechanics, Physics - Chemical Physics, Physics - Optics
Abstract

In a fully-controllable experiment platform for studying non-Markovian open quantum dynamics, we show that the non-Markovianity could be investigated from the global and local aspects. By mixing random unitary dynamics, we demonstrate non-Markovian and Markovian open quantum dynamics. From the global point of view, by tuning the base frequency we demonstrate the transition from the Markovianity to the non-Markovianity as measured by the quantum mutual information (QMI). In a Markovian open quantum process, the QMI decays monotonically, while it may rise temporarily in a non-Markovian process. However, under some circumstances, it is not sufficient to globally investigate the non-Markovianity of the open quantum dynamics. As an essential supplement, we further utilize the quantum Fisher information (QFI) flow to locally characterize the non-Markovianity in different channels. We demonstrate that the QMI in combination with the QFI flow are capable of measuring the non-Markovianity for a multi-channel open quantum dynamics., Comment: 15 pages, 4 figures, to be published in npj Quantum Inf

Published
2022
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12. Exact and efficient quantum simulation of open quantum dynamics for various of Hamiltonians and spectral densities

Author

Zhang, Na-Na, Tao, Ming-Jie, He, Wan-Ting, Chen, Xin-Yu, Kong, Xiang-Yu, Deng, Fu-Guo, Lambert, Neill, Ai, Qing, and Cheng, Yuan-Chung

Subjects
Quantum Physics, Physics - Atomic Physics, Physics - Chemical Physics, Physics - Optics
Abstract

Recently, we have theoretically proposed and experimentally demonstrated an exact and efficient quantum simulation of photosynthetic light harvesting in nuclear magnetic resonance (NMR), cf. B. X. Wang, \textit{et al.} npj Quantum Inf.~\textbf{4}, 52 (2018). In this paper, we apply this approach to simulate the open quantum dynamics in various photosynthetic systems with different Hamiltonians. By numerical simulations, we show that for Drude-Lorentz spectral density the dimerized geometries with strong couplings within the donor and acceptor clusters respectively exhibit significantly-improved efficiency. Based on the optimal geometry, we also demonstrate that the overall energy transfer can be further optimized when the energy gap between the donor and acceptor clusters matches the peak of the spectral density. Moreover, by exploring the quantum dynamics for different types of spectral densities, e.g. Ohmic, sub-Ohmic, and super-Ohmic spectral densities, we show that our approach can be generalized to effectively simulate open quantum dynamics for various Hamiltonians and spectral densities. Because $\log_{2}N$ qubits are required for quantum simulation of an $N$-dimensional quantum system, this quantum simulation approach can greatly reduce the computational complexity compared with popular numerically-exact methods., Comment: 12 pages, 4 figures

Published
2020
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17. Frequency-tuning induced state transfer in optical microcavities

Author

Xu, Xu-sheng, Zhang, Hao, Kong, Xiang-Yu, Wang, Min, and Long, Gui-Lu

Subjects
Physics - Optics, Quantum Physics
Abstract

Quantum state transfer in optical microcavities plays an important role in quantum information processing, and is essential in many optical devices, such as optical frequency converter and diode. Existing schemes are effective and realized by tuning the coupling strengths between modes. However, such approaches are severely restricted due to the small amount of strength that can be tuned and the difficulty to perform the tuning in some situations, such as on-chip microcavity system. Here, we propose a novel approach that realizes the state transfer between different modes in optical microcavities by tuning the frequency of an intermediate mode. We showed that for typical functions of frequency-tuning, such as linear and periodic functions, the state transfer can be realized successfully with different features. To optimize the process, we use gradient descent technique to find an optimal tuning function for the fast and perfect state transfer. We also showed that our approach has significant nonreciprocity with appropriate tuning variables, where one can unidirectionally transfer a state from one mode to another, but the inverse direction transfer is forbidden. This work provides an effective method for controlling the multimode interactions in on-chip optical microcavities via simple operations and it has practical applications in all-optical devices., Comment: 7 pages, 7 figures. Comments are welcome to xuxs15@mails.tsinghua.edu.cn or zhanghaoguoqing@163.com

Published
2019

28. Metal‐Phosphonate‐Organic Network as Ion Enrichment Layer for Sustainable Zinc Metal Electrode with High Rate Capability.

Author

He, Xiaofeng, Qian, Yongchao, Wu, Yadong, Yan, Zidi, Lin, Xiangbin, Kong, Xiang‐Yu, Zhao, Yong, Jiang, Lei, and Wen, Liping

Subjects
ZINC electrodes, SUSTAINABLE chemistry, ANODES, METAL ions, STORAGE batteries
Abstract

Zinc (Zn) metal batteries could be the technology of choice for sustainable battery chemistries owing to its better safety and cost advantage. However, their cycle life and Coulombic efficiency (CE) are strongly limited by the dendritic growth and side reactions of Zn anodes. Herein, we proposed an in situ construction of a metal‐phosphonate‐organic network (MPON) with three‐dimensional interconnected networks on Zn metal, which can act as an ion enrichment layer for Zn anodes in Zn‐metal batteries. This MPON with abundant porous structure and phosphate sites possesses ion enriching properties and high Zn2+ transference number (0.83), which is beneficial for enhancing Zn2+ migration and self‐concentrating kinetics. Meanwhile, MPON offers hydrophobicity to effectively inhibit the water‐induced Zn anode corrosion. As a result, the Zn electrode exhibits superior Zn/Zn2+ reversibility of over 4 months at 3 mA cm−2 and a high CE of 99.6 %. Moreover, the Zn/NaV3O8 ⋅ 1.5H2O and Zn/MnO2 full cells using ultrathin Zn anodes (10 μm) exhibit high‐capacity retention of 81 % and 78 % after 1400 and 1000 cycles, respectively. This work provides a unique promise to design high‐performance anode for practical Zn‐metal‐based batteries. [ABSTRACT FROM AUTHOR]

Published
2024
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43. Bioinspired carbon nanotube–based nanofluidic ionic transistor with ultrahigh switching capabilities for logic circuits

Author

Liu, Wenchao, primary, Mei, Tingting, additional, Cao, Zhouwen, additional, Li, Chun, additional, Wu, Yitian, additional, Wang, Li, additional, Xu, Guoheng, additional, Chen, Yuanxia, additional, Zhou, You, additional, Wang, Senyao, additional, Xue, Yahui, additional, Yu, Yanhao, additional, Kong, Xiang-Yu, additional, Chen, Ruotian, additional, Tu, Bin, additional, and Xiao, Kai, additional

Published
2024
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48. Secure State Estimation for Train-to-Train Communication Systems: A Neural Network-Aided Robust EKF Approach

Author

Kong, Xiang-Yu and Yang, Guang-Hong

Abstract

This article studies the problem of secure state estimation for train-to-train communication systems subject to deception attacks. Different from the existing secure state estimation methods for linear systems suffering from the occasionally occurring deception attacks, a neural network (NN)-aided robust extended Kalman filter (EKF) method is proposed for nonlinear discrete train systems, where the proposed method introduces a residual saturation function to render the EKF robust against deception attacks of different magnitudes and durations, and a sufficient condition is derived to guarantee the boundedness of the estimation errors. When attacks occur, the distorted residual of the EKF is able to be limited to a finite range due to the saturation constraint, which alleviates the negative effects induced by the deception attacks on the estimation performance. To further improve the estimation accuracy, the NN is used to cascade with the EKF for predicting and correcting the estimation errors of the filter online. Experiments on a semiphysical platform validate the effectiveness and advantage of the proposed method in different scenarios.

Published
2024
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