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Obtaining better performance in the measurement-device-independent quantum key distribution with heralded single-photon sources

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Physical Review A 2017年第5期96卷 052337-052337页

作者： Xing-Yu Zhou Chun-Hui Zhang Chun-Mei Zhang Qin Wang Institute of Signal Processing and Transmission Nanjing University of Posts and Telecommunications Nanjing 210003 China Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Ministry of Education Nanjing 210003 China Key Laboratory of Quantum Information University of Science and Technology of China Hefei 230026 China

Measurement-device-independent quantum key distribution (MDI-QKD) has been widely investigated due to its remarkable advantages on the achievable transmission distance and practical security. However, the relative low key generation rate limits its real-life implementations. In this work, we adopt the newly proposed four-intensity decoy-state scheme [Phys. Rev. A 93, 042324 (2016)] to study the performance of MDI-QKD with heralded single-photon sources (HSPS). Corresponding simulation results demonstrate that the four-intensity decoy-state scheme combining HSPS can drastically improve both the key generation rate and transmission distance in MDI-QKD, which may be very promising in future MDI-QKD systems.

关键词： Quantum cryptography

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Application of an improved threshold segmentation method in SEM material analysis

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IOP Conference Series: Materials Science and Engineering 2018年第2期322卷

作者： Denghui Li Yanhong Wang Institute Of Information Technology of Guilin University of Electronic Technology Guangxi Key Lab of Wireless Wideband Communication & Signal Processing Guilin China Key Laboratory of Cognitive Radio and Information Processing Ministry of Education (Guilin University of Electronic Technology) GUET Guilin China

Threshold analysis is a common method of image analysis. It is difficult to separate the target from the background with only one threshold method for more complex images. An improved multi threshold segmentation algorithm is proposed based on the characteristics of the SEM material itself. The all completed experimental results show that the algorithm is effective.

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A Top-down SCMA Codebook Design Scheme Based on Lattice Theory

A Top-down SCMA Codebook Design Scheme Based on Lattice Theo...

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IEEE Annual International Symposium on Personal, Indoor, and Mobile Radio communications

作者： Haonan Yan Hui Zhao Zhaobiao Lv Haojun Yang Key Laboratory of Universal Wireless Communication Ministry of Education Wireless Signal Processing & Network Lab BUPT

ISBN: (纸本)9781509032556

Recent work on multiple access has shown sparse code multiple access (SCMA) is a promising scheme dealing with massive connection. In SCMA systems, symbol spreading is combined with symbol mapping. The coded bits are directly mapped to the spread symbols, called codewords, according to SCMA codebook. Several codewords are superposed on the same resource. Since codebook is essential to SCMA system performance, this paper aims to present a novel top-down codebook design scheme for SCMA. Firstly, a geometrically uniform top-layer mother constellation with good energy efficiency is proposed based on lattice theory. After dividing the top layer constellation into several bottom layer constellations, we use matrix operation to optimize their distance spectrums. Then a mapping principle between users and resource is proposed to construct the final codewords. Simulation results shows that this top-down codebook outperforms existing schemes in bit error ratio (BER) while sharply reduce the peak to average power ratio (PAPR).

关键词： SCMA Codebook design Top-down Lattice theory PAPR

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Deterministic realization of collective measurements via photonic quantum walks

Deterministic realization of collective measurements via pho...

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第十八届全国量子光学学术会议

作者：侯志博 Jun-Feng Tang Yuan Yuan Kang-Da Wu Guo-Yong Xiang Chuan-Feng Li Guang-Can Guo Jiangwei Shang Huangjun Zhu Jian Li 中科大 Key Laboratory of Quantum Information University of Science and Technology of ChinaCAS Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of China Naturwissenschaftlich-Technische Fakult?t Universit?t Siegen Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems School of PhysicsBeijing Institute of Technology Institute for Theoretical Physics University of Cologne Department of Physics and Center for Field Theory and Particle Physics Fudan University State Key Laboratory of Surface Physics Fudan University Collaborative Innovation Center of Advanced Microstructures Institute of Signal Processing Transmission Nanjing University of Posts and Telecommunications Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and TelecommunicationsMinistry of Education

Collective measurements on identically prepared quantum systems can extract more information than local measurements, thereby enhancing information-processing efficiency. Although this nonclassical phenomenon has been known for two decades, it has remained a challenging task to demonstrate the advantage of collective measurements in experiments. Here, we introduce a general recipe for performing deterministic collective measurements on two identically prepared qubits based on quantum walks. Using photonic quantum walks, we realize experimentally an optimized collective measurement with fidelity 0.9946 without post selection. As an application, we achieve the highest tomographic efficiency in qubit state tomography to date. Our work offers an effective recipe for beating the precision limit of local measurements in quantum state tomography and metrology. In addition, our study opens an avenue for harvesting the power of collective measurements in quantum information processing and for exploring the intriguing physics behind this power.

关键词： Deterministic realization of collective measurements via photonic quantum walks

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Biased decoy-state reference-frame-independent quantum key distribution

arXiv

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arXiv 2017年

作者： Zhu, Jian-Rong Zhang, Chun-Mei Guo, Guang-Can Wang, Qin Institute of Signal Processing Transmission Nanjing University of Posts and Telecommunications Nanjing210003 China Key Lab of Broadband Wireless Communication and Sensor Network Technology Nanjing University of Posts and Telecommunications Ministry of Education Nanjing210003 China Key Laboratory of Quantum Information CAS University of Science and Technology of China Hefei230026 China

Without actively aligning the reference frames, the reference-frame-independent quantum key distribution (RFI-QKD) can generate secure keys even when the reference frames drift slowly. Here, we propose a new scheme on the decoy-state RFI-QKD, where the basis assignments of two legitimate parties are biased, reducing the fraction of mismatched-basis data. When accounting for statistical fluctuations under different misalignments of reference frames, we investigate the performance of biased decoy-state RFI-QKD with full parameter optimization. We also make a clear comparison between the new scheme with other practical schemes, e.g., unbiased decoy-state RFI-QKD and biased decoy-state BB84-QKD. Simulation results demonstrate that the new proposed biased decoy-state RFI-QKD can significantly improve the performance (secret key rate and secure transmission distance) of practical QKD systems. Copyright © 2017, The Authors. All rights reserved.

关键词： Quantum cryptography

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Multiuser Beamforming with Limited Feedback for FDD Massive MIMO Systems

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Chinese Journal of Engineering 2016年第1期2016卷

作者： Zheng, Senyao Zhao, Hui Zhao, Long Mei, Jie Tang, Weimin Wireless Signal Processing and Network (WSPN) Lab BUPT Key Laboratory of Universal Wireless Communication Ministry of Education Beijing 100876 China

This paper discusses the multiuser beamforming in FDD massive MIMO systems. It first introduces the feature of FDD massive MIMO systems to implement multiuser beamforming schemes. After that, considering the realistic implementation of multiuser beamforming scheme in FDD massive MIMO systems, it introduces the knowledge of channel quantization. In the main part of the paper, we introduce two traditional multiuser beamforming schemes and analyse their merits and demerits. Based on these, we propose a novel multiuser beamforming scheme to flexibly combine the merits of the traditional beamforming schemes. In the final part of the paper, we give some simulation results to compare the beamforming schemes mentioned in the paper. These simulation results show the superiority of the proposed beamforming scheme. © 2016 Senyao Zheng et al.

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Low-complexity interference cancellation receiver for sparse code multiple access 6

Low-complexity interference cancellation receiver for sparse...

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6th IEEE International Symposium on Microwave, Antenna, Propagation, and EMC Technologies, MAPE 2015

作者： Jia, Zou Hui, Zhao Zhao, Wenxiu Key Laboratory of Universal Wireless Communication Ministry of Education Wireless Signal Processing and Network Lab BUPT Beijing China

ISBN: (纸本)9781467374415

Sparse code multiple access (SCMA) is a proposed candidate for multiple access method in 5G telecommunication. In SCMA system, the classic receiver is message passing algorithm (MPA). MPA can reach a near optimal performance, but the computation process is complicated and time-consuming, so MPA is suitable for advanced terminal. But for simple terminal such as sensor node, large mount of calculations are difficult to bear. In this paper, we propose two interference cancellation (IC) related receivers to reduce complexity, including serial interference cancellation (SIC) and jointed serial interference cancellation with MPA algorithm (Jointed SIC-MPA). It's important to emphasize that these two IC related algorithms are designed jointed with multi-dimensional modulation constellation design. We propose a new method to generate multi-dimensional constellation. Both of them have lower complexity compared with classic MPA receiver. © 2015 IEEE.

关键词： Integrated circuits

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A low-complexity tree search based quasi-ML receiver for SCMA system

A low-complexity tree search based quasi-ML receiver for SCM...

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IEEE International Conference on Computer and communications, ICCC 2015

作者： Jia, Zou Hui, Zhao Xing, Li Key Laboratory of Universal Wireless Communication Ministry of Education Wireless Signal Processing and Network Lab BUPT Beijing China

ISBN: (纸本)9781467381253

Sparse code multiple access (SCMA) which is overloaded by carrying more users than its resource blocks, is different from conventional multiple access method. It can improve spectrum efficiency to solve the problem of large amounts of telecommunication data. Conventional message passing algorithm (MPA) receiver has been used in SCMA, but it has a relatively high complexity. In this paper, we propose a new low-complexity quasi maximum likelihood (quasi-ML) receiver to further reduce the complexity. Quasi-ML receiver is improved for the specific characteristic of SCMA. Numerical results demonstrate that the quasi-ML detector achieves significantly less computational complexity than the classic MPA detector, with a little performance loss. The superior performance of the proposed algorithm is demonstrated by theoretic analysis as well as simulation results. © 2015 IEEE.

关键词： Message passing

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A novel codeword grouped SCMA 6

A novel codeword grouped SCMA

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6th IEEE International Symposium on Microwave, Antenna, Propagation, and EMC Technologies, MAPE 2015

作者： Wang, Jun Hui, Zhao Peng, Yuexing Sha, Liu Zheng, Senyao Key Laboratory of Universal Wireless Communication Ministry of Education Wireless Signal Processing and Network Lab BUPT Beijing100876 China

ISBN: (纸本)9781467374415

In the future 5G, the fast-growing requirements of massive connectivity, higher data-rate transmissions and multiple services should be matched with new multiple access technology. Non-orthogonal multiple access, nowadays, is considered as an effective method to solve those problems. Some non-orthogonal multiple access technologies, e.g. low density signature (LDS) and sparse code multiple access (SCMA), are proposed nowadays for substantial connectivity together with spectrum efficiency promotion. Instead of spreading data symbols over orthogonal or near orthogonal code sequences in CDMA, those non-orthogonal multiple access technologies take advantage of non-orthogonal code sequences. The LDS repeatedly spreads quadrature amplitude modulation (QAM) symbol according to the low density sequence, while the SCMA assigns different predefined codebooks to multiple layers. However, the SCMA codebooks made from multi-dimensional constellations are designed under the condition of same modulation order for each layer. The design scheme of SCMA codebook is regardless of the orthogonality among some certain layers. A novel codeword grouped SCMA (CG-SCMA) proposed in this paper allows diverse modulations and enhances the applicability of the non-orthogonal multiple access technology. Instead of mapping incoming bits to multi-dimensional codewords from predefined codebooks in SCMA, the procedure of symbols to complex codewords is divided into two steps: grouped indicator sequence spread and grouped symbol sequence rotation. The grouped symbol sequence rotation decreases the interference among layers and increases the signal space diversity, which is regarded as the main source of performance promotion. Simulation results are presented to show the significant performance gain of CG-SCMA comparing with SCMA and LDS. © 2015 IEEE.

关键词： Modulation

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A Compressive Channel Sensing Method with Optimal Thresholding for OFDM Systems under Fast Fading Channels

A Compressive Channel Sensing Method with Optimal Thresholdi...

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IEEE wireless communications and networking Conference

作者： Da Fu Yuexing Peng Senyao Zheng Wireless Signal Processing & Network Lab Key Laboratory of Universal Wireless Communication Ministry of Education Beijing University of Posts & Telecommunications

ISBN: (纸本)9781467398152

In Orthogonal Frequency Division Multiplexing (OFDM) systems, the high-speed movement between the transmitter and receiver would cause large Doppler shifts, which will degrade the channel estimation severely due to the channel power dispersion. Moreover, the channel structure may vary fast such that the channel structure-based estimation methods cannot work properly. Therefore, one key challenge is to design an efficient and reliable estimation method to adapt to the fast time-varying channels in high-speed movement scenarios. In this paper, a basis expansion model (BEM) based compressive channel sensing algorithm is proposed to estimate the channel state information (CSI) for OFDM systems under fast fading channels. In order to mitigate the channel power leakage, Discrete Prolate Spheroidal Sequences (DPSS) are employed as the basis of the channel model. By fully exploiting the sparse characteristics of the channel, an Orthogonal Matching Pursuit (OMP) algorithm with optimal thresholding is developed, which can flexibly support the varying channel structure without channel side information. Numerical simulation results verify the efficiency of the proposed method for the fast time-varying fading channels.

关键词： Channel estimation Compressive sensing DPSS OFDM Thresholding

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