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中国科学：信息科学（英文版）
中国科学：信息科学（英文版）

周光召

月刊

1674-733X

informatics@scichina.org

010-64015683

100717

北京东黄城根北街16号

中国科学：信息科学（英文版）/Journal Science China Information SciencesCSCDCSTPCDEISCI
查看更多>>《中国科学》是中国科学院主办、中国科学杂志社出版的自然科学专业性学术刊物。《中国科学》任务是反映中国自然科学各学科中的最新科研成果，以促进国内外的学术交流。《中国科学》以论文形式报道中国基础研究和应用研究方面具有创造性的、高水平的和有重要意义的科研成果。在国际学术界，《中国科学》作为代表中国最高水平的学术刊物也受到高度重视。国际上最具有权威的检索刊物SCI，多年来一直收录《中国科学》的论文。1999年《中国科学》夺得国家期刊奖的第一名。
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    Achieving full mutualism with massive passive devices for multiuser MIMO symbiotic radio

    Jingran XUZhuoyin DAIYong ZENGShi JIN...
    192-208页
    查看更多>>摘要：Symbiotic radio(SR)is one of the attractive communication technologies to facilitate large-scale Internet of Things(IoT)connections with enhanced energy and spectrum efficiency,where passive backscatter devices(BDs)modulate their information over the radio frequency(RF)signals emitted by the active primary transmitters(PTs).Meanwhile,the primary transmission can be strengthened with the additional multipaths created by BDs.To capitalize to a greater extent on the mutualism relationship between the two types of communication,this paper studies multiple-input multiple-output(MIMO)SR communication systems including multiple PTs and massive BDs..We derive the achievable rate expressions of each PT and BD,as well as the sum rate expressions of primary and secondary communication,respectively.Then asymptotic analysis is given to derive the active and passive communication rates with a large number of BDs.Furthermore,for the general case with a finite number of BDs,we study the precoding optimization problem to maximize the sum rate of primary communication,while ensuring that the sum rate of secondary communication and the individual rate for each PT and BD in the prescribed active and passive user sets satisfy the specified thresholds.Simulation results are presented to verify the analytical studies.
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    Near-field channel estimation for extremely large-scale Terahertz communications

    Songjie YANGYizhou PENGWanting LYUYa LI...
    209-224页
    查看更多>>摘要：Future Terahertz communications exhibit significant potential in accommodating ultra-high-rate services.Employing extremely large-scale array antennas is a key approach to realize this potential,as they can harness substantial beamforming gains to overcome the severe path loss and leverage the electromagnetic advantages in the near field.This paper proposes novel estimation methods designed to enhance efficiency in Terahertz widely-spaced multi-subarray(WSMS)systems.Initially,we introduce three sparse channel representation methods:polar-domain representation(PD-R),multi-angular-domain representation(MAD-R),and two-dimensional polar-angular-domain representation(2D-PAD-R).Each method is meticulously developed for near-field WSMS channels,capitalizing on their sparsity characteristics.Building on this,we propose four estimation frameworks using the sparse recovery theory:polar-domain estimation(PD-E),multi-angular-domain estimation(MAD-E),two-stage polar-angular-domain estimation(TS-PAD-E),and two-dimensional polar-angular-domain estimation(2D-PAD-E).Particularly,2D-PAD-E,integrating a 2D dictionary process,and TS-PAD-E,with its sequential approach to angle and distance estimation,stand out as particularly effective for near-field angle-distance estimation,enabling decoupled calculation of these parameters.Overall,these frameworks provide versatile and efficient solutions for WSMS channel estimation,balancing low complexity with high-performance outcomes.Additionally,they represent a fresh perspective on near-field signal processing.
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    Data delivery delay and cross-layer packet size analysis for reliable transmission of Licklider transmission protocol in space networks

    Guannan YANGRuhai WANGKanglian ZHAOWenfeng LI...
    225-240页
    查看更多>>摘要：Delay/disruption tolerant networking(DTN)is proposed as a networking architecture to over-come challenging space communication characteristics for reliable data transmission service in presence of long propagation delays and/or lengthy link disruptions.Bundle protocol(BP)and Licklider Transmission Protocol(LTP)are the main key technologies for DTN.LTP red transmission offers a reliable transmission mechanism for space networks.One of the key metrics used to measure the performance of LTP in space applications is the end-to-end data delivery delay,which is influenced by factors such as the quality of spatial channels and the size of cross-layer packets.In this paper,an end-to-end reliable data delivery delay model of LTP red transmission is proposed using a roulette wheel algorithm,and the roulette wheel algorithm is more in line with the typical random characteristics in space networks.The proposed models are validated through real data transmission experiments on a semi-physical testing platform.Furthermore,the impact of cross-layer packet size on the performance of LTP reliable transmission is analyzed,with a focus on bundle size,block size,and segment size.The analysis and study results presented in this paper offer valuable contributions towards enhancing the reliability of LTP transmission in space communication scenarios.
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    Repeat-pass space-surface bistatic SAR tomography:accurate imaging and first experiment

    Zhiyang CHENYuanhao LICheng HUShenglei WANG...
    241-258页
    查看更多>>摘要：Space-surface bistatic synthetic aperture radar(SS-BiSAR)offers an additional observation angle for monostatic spaceborne SAR,making it a promising technology for high-accuracy deformation retrieval technology in local regions.Repeat-pass SS-BiSAR tomography can accurately estimate the surfaces of buildings and steep areas,effectively removing terrain phases during deformation retrieving.However,in-accuracies in the orbital ephemeris can lead to image geometry distortion,reducing image pair coherence,introducing interferometric phase errors,and consequently deteriorating tomographic precision.This pa-per precisely models the image geometry distortion and interferometric phase error caused by repeat-pass ephemeris error.We propose an ephemeris correction method based on the chirp-Z transform to address these issues.Furthermore,we introduce an accurate tomography model to improve 3D reconstruction accuracy.Our first SS-BiSAR tomography experiment,conducted using the Chinese Lutan-1 satellite,demonstrates that the correlation coefficient is improved by 0.16 after ephemeris error correction.Moreover,the density and precision of the tomographic point cloud are improved by 13.7％and 12.1％,respectively.
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    Orthogonal waveform design with fractional programming on the ambiguity suppression of SAR systems

    Yunkai DENGYongwei ZHANGZhimin ZHANGWei WANG...
    259-275页
    查看更多>>摘要：Waveform diversity(WD)represents a dynamic and transformative technology widely used in radar systems to enhance sensitivity and discrimination capabilities.Recently,WD techniques have been ex-tensively explored for their potential ambiguity suppression within synthetic aperture radar(SAR)systems.Among these,the alternate transmitting mode combined with orthogonal waveforms emerges as a particularly promising solution.This study focuses on optimizing the power spectrum density(PSD)of signals to design and generate an orthogonal waveform pair that achieves both a low cross-correlation-to-autocorrelation ratio(CAR)and satisfactory imaging performance.Initially,we construct a fractional programming model with convex constraints to minimize the CAR.To address this challenge,we introduce an iterative optimization procedure for the PSD variable,which sequentially reduces the CAR.Each optimization step can be effi-ciently solved using a quadratically constrained quadratic program,ensuring that the resulting computational complexity remains low.Building on the optimized PSD,we established a parametric piecewise linear model to generate an orthogonal waveform pair.This model not only maintains a low CAR but achieves satisfac-tory imaging performance in real-time applications.Consequently,this orthogonal waveform pair effectively suppresses range ambiguity in SAR systems.Finally,we demonstrated the practicability and effectiveness of the proposed orthogonal waveforms through detailed simulation experiments,specifically targeting ambiguity suppression in conventional quad-polarization SAR systems.
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    Flexible printed three dimensional(3D)integrated carbon nanotube complementary metal oxide semiconductor(CMOS)thin film transistors and circuits

    Zhaofeng CHENJiaqi LIMin LIHongxuan GUO...
    276-289页
    查看更多>>摘要：The threshold voltage modulation of carbon nanotube thin-film transistors(TFTs)and flexible three-dimensional(3D)integration circuits has become hot research topics for carbon-based electronics.In this paper,a doping-free gate electrode technology is introduced to significantly modulate the threshold voltage of polymer-sorted semiconducting single-walled carbon nanotube(sc-SWCNT)TFTs in combination with the highly effective gate-controlling ability of solid-state electrolyte thin films as the dielectrics.A systematic investigation was conducted on the impact of printed silver,evaporated silver,and evaporated aluminum(Al)gate electrodes on the threshold voltage of flexible printed bottom-gate and top-gate SWCNT TFTs.The results indicate that the SWCNT TFTs with Al gate electrodes exhibit enhancement-mode characteristics with excellent electrical properties,such as the negative threshold voltages(-0.6 V),high Ion/Ioff(up to 106),low subthreshold swing(61.4 mV·dec-1),and small hysteresis.It is attributed to either the formation of lower work function thin films(Al2O3)at the electrode/dielectric layer interfaces through the natural oxidation of the Al bottom-gate electrodes or the dipole reaction of the Al top-gate electrodes from X-ray photoelectron spectroscopy(XPS)and ultraviolet photoelectron spectroscopy(UPS)data.In addition,3D complementary metal-oxide-semiconductor(CMOS)inverters with common gate electrodes were constructed using the resulting enhancement-mode P-type SWCNT TFTs and matched N-type SWCNT TFTs,which shows high voltage gain(34),rail-to-rail output and high noise margins(80.04％,VDD=-1V)as well good mechanical flexibility at low operation voltages.It demonstrates that SWCNT TFTs have great advantages for building large-scale 3D flexible integrated circuits.
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    Probing quantum causality with geometric asymmetry in spatial-temporal correlations

    Yu MENGZheng-Hao LIUZhikuan ZHAOPeng YIN...
    290-301页
    查看更多>>摘要：Causation promotes the understanding of correlation to an advanced stage by elucidating its underlying mechanism.Although statisticians have specified the possible causal relations among correlations,inferring causal structures is impossible from only the observed correlations in the classical world.Quantum correlations encapsulating the most defining aspects of quantum physics have taken a new turn for the causal inference problem—the two-point spatial and temporal quantum correlations with observationally discernible characteristics correspond exactly to the two most basic causal structures.However,a direct causal interpretation for quantum correlations has only been established in very limited cases.Here,we explore to what extent quantum correlations promote causal inference.Theoretically,we have found that the distinguishable causal regime of two-point Pauli correlations can be expanded from a single value to an asymmetric interval,and the causal structures determining the quantum correlations can be interpreted by a simple distance criterion.Experimentally,we have devised and implemented a versatile non-unital quantum channel in an optical architecture to directly observe such an asymmetric interval.The setup enabled quantum causal inference without any requirement of active intervention,which is impossible in the classical realm.Our work facilitates the identification of causal links among quantum variables and provides insight into characterizing causation and spatial-temporal correlation in quantum mechanics.
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    The quantum Ising model for perfect matching and solving it with variational quantum eigensolver

    Qilin ZHENGPingyu ZHUChao WUMiaomiao YU...
    302-316页
    查看更多>>摘要：Obtaining all perfect matchings of a graph is a tough problem in graph theory,and its complex-ity belongs to the #P-Complete class.The problem is closely related to combinatorics,marriage matching problems,dense subgraphs,the Gaussian boson sampling,chemical molecular structures,and dimer physics.In this paper,we propose a quadratic unconstrained binary optimization formula of the perfect matching problem and translate it into the quantum Ising model.We can obtain all perfect matchings by mapping them to the ground state of the quantum Ising Hamiltonian and solving it with the variational quantum eigensolver.Adjusting the model's parameters can also achieve the maximum or minimum weighted per-fect matching.The experimental results on a superconducting quantum computer of the Origin Quantum Computing Technology Company show that our model can encode 2n dimensional optimization space with only O(n)qubits consumption and achieve a high success probability of the ground state corresponding to all perfect matchings.In addition,the further simulation results show that the model can support a scale of more than 14 qubits,effectively resist the adverse effects of noise,and obtain a high success probability at a shallow variational depth.This method can be extended to other combinatorial optimization problems.
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    Quantum search with prior knowledge

    Xiaoyu HEXiaoming SUNJialing ZHANG
    317-325页
    查看更多>>摘要：The combination of contextual side information and search is a powerful paradigm in the scope of artificial intelligence.The prior knowledge enables the identification of possible solutions but may be imperfect.Contextual information can arise naturally,for example in game AI where prior knowledge is used to bias move decisions.In this work we investigate the problem of taking quantum advantage of contextual information,especially searching with prior knowledge.We propose a new generalization of Grover's search algorithm that achieves the optimal expected success probability of finding the solution if the number of queries is fixed.Experiments on small-scale quantum circuits verify the advantage of our algorithm.Since contextual information exists widely,our method has wide applications.We take game tree search as an example.
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    A mixed Nash equilibrium solution for visibility-based pursuit-evasion game with multiple obstacles

    Shaoming BULi LIANGYouqing WANG
    326-328页
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