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Multiple asymmetric couplings induced unconventional corner mode in topolectrical circuits

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arXiv 2024年

作者： Jiang, Hengxuan Wang, Xiumei Chen, Jie Zhou, Xingping College of Integrated Circuit Science and Engineering Nanjing University of Posts and Telecommunications Nanjing210003 China College of Electronic and Optical Engineering Nanjing University of Posts and Telecommunications Nanjing210003 China Institute of Quantum Information and Technology Key Lab of Broadband Wireless Communication and Sensor Network Technology Ministry of Education Nanjing University of Posts and Telecommunications Nanjing210003 China

We investigate the emergence of unconventional corner mode in a two-dimensional topolectrical circuits induced by asymmetric couplings. The non-Hermitian skin effect of two kinked one-dimensional lattices with multiple asymmetric couplings are explored. Then we extend to the two-dimensional model, derive conditions for the non-Hermitian hybrid skin effect and show how the corner modes are formed by nonreciprocal pumping based on one-dimensional topological modes. We provide explicit electrical circuit setups for realizing our observations via realistic LTspice simulation. Moreover, we show the time varying behaviors of voltage distributions to confirm our results. Our study may help to extend the knowledge on building the topological corner modes in the non-Hermitian presence. © 2024, CC BY.

关键词： Topology

Privacy amplification scheme based on composite coding

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arXiv 2021年

Privacy amplification is an indispensable step in the post-processing of quantum key distribution, which can be used to compress the redundancy of shared key and improve the security level of the key. The commonly used privacy amplification is based on the random selection of universal hash functions, which needs the help of an additional random source, while it does not exist in general. In this paper, we propose a privacy amplification scheme based on composite coding, which is an extension of quantum CSS codes to classical linear codes. Compared with the universal hashing function, the proposed scheme does not need other random sources, and the randomness can be completely provided by the qubit string. Furthermore, the information-theoretic bound for the extraction of the key is obvious in composite coding. Copyright © 2021, The Authors. All rights reserved.

关键词： Quantum cryptography

Wave-particle duality in single-photon entanglement

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arXiv 2019年

The simplest single-photon entanglement is the entanglement of the vacuum state and the single-photon state between two path modes. The verification of the existence of single-photon entanglement has attracted extensive research interests. Here, based on the construction of Bell’s inequality in wave space, we propose a new method to verify single photon entanglement. Meanwhile, we define the wave state in two-dimensional space relative to the photon number state, and propose a method to measure it. Strong violation of Bell inequality based on joint measurement of wave states indicates the existence of single photon entanglement with certainty. Wave state entanglement obtained from Fourier transform of single photon entanglement and the corresponding measurement protocols will provide us with more information-carrying schemes in the field of quantum information. The difference in the representation in photon-number space and wave space implies the wave-particle duality of single photon entanglement. Copyright © 2019, The Authors. All rights reserved.

关键词： Particle beams

The optimal positive operator-valued measure for state discrimination

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arXiv 2021年

Evaluating the amount of information obtained from non-orthogonal quantum states is an important topic in the field of quantum information. The commonly used evaluation method is Holevo bound, which only provides a loose upper bound for quantum measurement. In this paper, we provide a theoretical study of the positive operator-valued measure (POVM) for discriminating nonorthogonal states. We construct a generalized POVM measurement operation, and derive the optimal one for state discrimination by Lagrange multiplier method. With simulation, we find that the optimal POVM measurement provides a tight upper bound for state discrimination, which is significantly lower than that predicted by Holevo bound. The derivation of optimal POVM measurement will play an important role in the security research of quantum key distribution. Copyright © 2021, The Authors. All rights reserved.

关键词： Quantum cryptography

Phase matching quantum key distribution based on single-photon entanglement

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arXiv 2019年

作者： Li, Wei Wang, Le Zhao, Shengmei Nanjing University of Posts and Telecommunications Institute of Signal Processing and Transmission Nanjing210003 China Nanjing University of Posts and Telecommunications Key Lab Broadband Wireless Communication and Sensor Network Ministy of Education Nanjing210003 China National Laboratory of Solid State Microstructures Nanjing University Nanjing210093 China

Two time-reversal quantum key distribution (QKD) schemes are the quantum entanglement based device-independent (DI)-QKD and measurement-device-independent (MDI)-QKD. The recently proposed twin field (TF)-QKD, also known as phase-matching (PM)-QKD, has improved the key rate bound from O(η) to O(√η) with η the channel transmittance. In fact, TF-QKD is a kind of MDIQKD but based on single-photon detection. In this paper, we propose a different PM-QKD based on single-photon entanglement, referred to as SEPM-QKD, which can be viewed as a time-reversed version of the TF-QKD. Detection loopholes of the standard Bell test, which often occur in DI-QKD over long communication distances, are not present in this protocol because the measurement settings and key information are the same quantity which is encoded in the local weak coherent state. We give a security proof of SEPM-QKD and demonstrate in theory that it is secure against all collective attacks and beam-splitting attacks. The simulation results show that the key rate enjoys a bound of O (√η) with respect to the transmittance. SEPM-QKD not only helps us understand TF-QKD more deeply, but also hints at a feasible approach to eliminate detection loopholes in DI-QKD for long-distance communications. Copyright © 2019, The Authors. All rights reserved.

关键词： Quantum cryptography

Joint Cooperation Clustering and Downlink Power Control for Cell-Free Massive MIMO with Deep Reinforcement Learning

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Joint Cooperation Clustering and Downlink Power Control for ...

International Conference on communication technology (ICCT)

作者： Mingjun Du Xinghua Sun Yue Zhang Junyuan Wang Pei Liu School of Electronics and Communication Engineering Sun Yat-sen University Shenzhen China Department of Electronic Information Engineering Shantou University Shantou China College of Electronic and Information Engineering Tongji University Shanghai China School of Information Engineering Wuhan University of Technology Wuhan China Key Lab of Broadband Wireless Communication and Sensor Network Technology Ministry of Education Nanjing University of Posts and Telecommunications Nanjing China

Recently, numerous clustering and power control approaches have been developed to optimize network performance for cell-free massive multiple-input multiple-output (MIMO) systems. Notably, deep reinforcement learning (DRL) has emerged as a promising solution for network optimization. This paper investigates the joint cooperation clustering and downlink power control problem in cell-free massive MIMO, utilizing the deep deterministic policy gradient (DDPG) algorithm to maximize the long-term global average proportional fairness (PF). Our results demonstrate that the proposed DDPG method effectively outperforms the baselines in both clustering and power control. Furthermore, the proposed scheme exhibits robustness as it maintains superior performance even as the number of clusters varies.

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Outage Probability and Power Allocation Analysis of AmBC-Enabled NOMA for Future IoT

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Outage Probability and Power Allocation Analysis of AmBC-Ena...

International Conference on communication technology (ICCT)

作者： Chongye Wang Yang Liu Cheng-Xiang Wang School of Internet of Things Engineering Jiangnan University Wuxi China Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Ministry of Education Nanjing China National Mobile Communications Research Laboratory School of Information Science and Engineering Southeast University Nanjing China Purple Mountain Laboratories Nanjing China

Ambient backscatter communication (AmBC) combined with non-orthogonal multiple access (NOMA) presents superior energy reusability and higher sum rate. However, existing studies failed to utilize the information of backscatter links. Therefore, to explore the impact of backscatter link, this paper employs three-user NOMA to improve the spectral efficiency. We propose a simple distance power allocation method to accomplish successive interference cancellation. Based on the Monte Carlo method, the outage probability of the proposal is analyzed. Our work provides a scheme for coexistence between AmBC and NOMA systems in the future Internet of Things.

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A general deep reinforcement learning framework for grant-free NOMA optimization in mURLLC

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arXiv 2021年

作者： Liu, Yan Deng, Yansha Zhou, Hui Elkashlan, Maged Nallanathan, Arumugam Key Laboratory of Ministry of Education in Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Nanjing210003 China School of Electronic Engineering and Computer Science Queen Mary University of London London United Kingdom Department of Engineering King's College London London United Kingdom

Grant-free non-orthogonal multiple access (GF-NOMA) is a potential technique to support massive Ultra-Reliable and Low-Latency communication (mURLLC) service. However, the dynamic resource configuration in GF-NOMA systems is challenging due to random traffics and collisions, that are unknown at the base station (BS). Meanwhile, joint consideration of the latency and reliability requirements makes the resource configuration of GF-NOMA for mURLLC more complex. To address this problem, we develop a general learning framework for signature-based GF-NOMA in mURLLC service taking into account the multiple access signature collision, the UE detection, as well as the data decoding procedures for the K-repetition GF and the Proactive GF schemes. The goal of our learning framework is to maximize the long-term average number of successfully served users (UEs) under the latency constraint. We first perform a real-time repetition value configuration based on a double deep Q-network (DDQN) and then propose a Cooperative Multi-Agent learning technique based on the DQN (CMA-DQN) to optimize the configuration of both the repetition values and the contention-transmission unit (CTU) numbers. Our results show that the number of successfully served UEs under the same latency constraint in our proposed learning framework is up to ten times for the K-repetition scheme, and two times for the Proactive scheme, more than that with fixed repetition values and CTU numbers. In addition, the superior performance of CMA-DQN over the conventional load estimation-based approach (LE-URC) demonstrates its capability in dynamically configuring in long term. Importantly, our general learning framework can be used to optimize the resource configuration problems in all the signature-based GF-NOMA schemes. Copyright © 2021, The Authors. All rights reserved.

关键词： Deep learning

Multigrating design for integrated single-atom trapping, manipulation, and readout

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Physical Review A 2022年第5期105卷 053520-053520页

作者： Aiping Liu Jiawei Liu Wei Peng Xin-Biao Xu Guang-Jie Chen Xifeng Ren Qin Wang Chang-Ling Zou Institute of Quantum Information and Technology Nanjing University of Posts and Telecommunications Nanjing 210003 China Broadband Wireless Communication and Sensor Network Technology Key Laboratory of Ministry of Education Nanjing University of Posts and Telecommunications Nanjing 210003 China CAS Key Laboratory of Quantum Information University of Science and Technology of China Hefei 230026 China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of China Hefei 230026 China State Key Laboratory of Quantum Optics and Quantum Optics Devices and Institute of Opto-Electronics Shanxi University Taiyuan 030006 China

An on-chip multigrating device is proposed to interface single atoms and integrated photonic circuits, by guiding and focusing lasers to the area ∼10 μm above the chip for trapping, state manipulation, and readout of single rubidium atoms. For the optical dipole trap, two 850-nm laser beams are diffracted and overlapped to form the lattice of a single-atom dipole trap, with the diameter of the optical dipole trap being around 2.7 μm. Similar gratings are designed for guiding a 780-nm probe laser to excite and also collect the fluorescence of Rb87 atoms. Such a device provides a compact solution for future applications of single atoms, including the single-photon source, single-atom quantum register, and single-atom quantum sensor.

关键词： Atom optics Photonics