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Entanglement based six-state quantum cryptography protocol: exact proof of security

LASER PHYSICS LETTERS 2023年第5期20卷 055203-055203页

作者： Kulik, S. P. Molotkov, S. N. Moscow MV Lomonosov State Univ Ctr Quantum Technol Moscow 119991 Russia Russian Acad Sci Inst Soid State Phys Chernogolovka 142432 Moscow Region Russia

A novel quantum key distribution (QKD) protocol is proposed, which uses six states of three states in two bases. The protocol provides a greater range of key distribution compared to known QKD protocols. The protocol has an accurate proof of secrecy based on fundamental entropy uncertainty relations, the use of which is possible with the entanglement version of the protocol. The implementation of the protocol does not require adjustment of the polarization state at the output of the communication line, since the receiving side does not use active polarization-sensitive elements-phase modulators, which virtually excludes active probing of the active elements of the system.

关键词： entanglement entropy uncertainty relations phase coding

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Gamma amplitude is coupled to opposed hippocampal theta-phase states during the encoding and retrieval of episodic memories in humans

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CURRENT BIOLOGY 2023年第9期33卷 1836-+页

作者： di Chanaz, Ludovico Saint Amour Perez-Bellido, Alexis Wu, Xiongbo Lozano-Soldevilla, Diego Pacheco-Estefan, Daniel Lehongre, Katia Conde-Blanco, Estefania Roldan, Pedro Adam, Claude Lambrecq, Virginie Frazzini, Valerio Donaire, Antonio Carreno, Mar Navarro, Vincent Valero-Cabre, Antoni Fuentemilla, Lluis Univ Barcelona Dept Cognit Dev & Educ Psychol Pg Vall Hebron 171 Barcelona 08035 Spain Univ Barcelona Inst Neurosci Pg Vall Hebron 171 Barcelona 08035 Spain Ludwig Maximilians Univ Munchen Dept Psychol Munich Germany Univ Politecn Madrid Ctr Biomed Technol Lab Clin Neurosci Crta M40Km 38 Pozuelo De Alarcon 28223 Madrid Spain Ruhr Univ Bochum Inst Cognit Neurosci Fac Psychol Dept Neuropsychol D-44801 Bochum Germany Sorbonne Univ Pitie Salpetriere Hosp APHP Inst CerveauICMINSERMCNRSParis Brain Inst 47-83 Blvd Hop F-75651 Paris 13 France Hosp Clin Barcelona Neurol Dept Epilepsy Program Inst Invest Biomed August Pi i Sunyer IDIBAPSEpi C Villarroel 170 Barcelona 08036 Spain Hop La Pitie Salpetriere AP HP Epilepsy Unit DMU Neurosci 47-83 Blvd Hop F-75651 Paris 13 France Hop La Pitie Salpetriere AP HP Dept Neurophysiol DMU Neurosci 47-83 Blvd Hop F-75651 Paris 13 France Hop La Pitie Salpetriere AP HP Ctr Reference Rare Epilepsies 47-83 Blvd Hop F-75651 Paris 13 France FRONTLAB team Cerebral Dynam Plast & Rehabil Grp CNRS UMR 7225 INSERM U1127 Paris France Open Univ Catalonia UOC Fac Hlth & Sci Neurosci & Informat Technol Res Program Cognit Neurolab Avinguda Tibidabo 39-43 Barcelona 08035 Spain Boston Univ Lab Cerebral Dynam Plast & Rehabil Sch Med 72 Concord St Boston MA 02118 USA Inst Biomed Res Bellvitge LHospitalet Llobregat C-Feixa Llarga S-NEdif Modular Lhospitalet De Llobregat 08907 Barcelona Spain

Computational models and in vivo studies in rodents suggest that the emergence of gamma activity (40-140 Hz) during memory encoding and retrieval is coupled to opposed-phase states of the underlying hip-pocampal theta rhythm (4-9 Hz).1-10 However, direct evidence for whether human hippocampal gamma -modulated oscillatory activity in memory processes is coupled to opposed-phase states of the ongoing theta rhythm remains elusive. Here, we recorded local field potentials (LFPs) directly from the hippocampus of 10 patients with epilepsy, using depth electrodes. We used a memory encoding and retrieval task whereby trial unique sequences of pictures depicting real-life episodes were presented, and 24 h later, participants were asked to recall them upon the appearance of the first picture of the encoded episodic sequence. We found theta-to-gamma cross-frequency coupling that was specific to the hippocampus during both the encoding and retrieval of episodic memories. We also revealed that gamma was coupled to opposing theta phases during both encoding and recall processes. Additionally, we observed that the degree of theta-gamma phase opposition between encoding and recall was associated with participants' memory per-formance, so gamma power was modulated by theta phase for both remembered and forgotten trials, although only for remembered trials the dominant theta phase was different for encoding and recall trials. The current results offer direct empirical evidence in support of hippocampal theta-gamma phase opposition models in human long-term memory and provide fundamental insights into mechanistic predictions derived from computational and animal work, thereby contributing to establishing similarities and differences across species.

关键词： episodic memory hippocampus theta oscillations gamma oscillations phase coding iEEG cross-frequency coupling

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Experimental Investigation of phase Coded FMCW for Sensing and Communications 15

Experimental Investigation of Phase Coded FMCW for Sensing a...

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15th European Conference on Antennas and Propagation (EuCAP)

作者： Kumbul, Utku Petrov, Nikita van der Zwan, Fred Vaucher, Cicero S. Yarovoy, Alexander Delft Univ Technol Dept Microelect Delft Netherlands NXP Semicond Eindhoven Netherlands

ISBN: (纸本)9788831299022

The phase coded FMCW and its properties for joint sensing and communication are studied. Two different receiver structures for the sensing properties of this waveform are compared theoretically and experimentally. It is shown both by simulations and experiments that the phased coded FMCW combines communication capabilities of PMCW and sensing capabilities of FMCW while using a realizable hardware complexity for an automotive radar.

关键词： phase coding FMCW PMCW joint sensing and communication phase coded FMCW

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Mitigation of the impact of Doppler-frequency-shift in a coherent random modulation LiDAR via phase-coded subcarrier modulation 8

Mitigation of the impact of Doppler-frequency-shift in a coh...

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Conference on Optical Metrology and Inspection for Industrial Applications VIII

作者： Yu, Fengxi Qiu, Bowen Zhang, Yawei Xu, Zhongyang Pan, Shilong Nanjing Univ Aeronaut & Astronaut Key Lab Radar Imaging & Microwave Photon Minist Educ Nanjing 210016 Peoples R China

ISBN: (数字)9781510646483

ISBN: (纸本)9781510646483;9781510646476

A coherent random modulation LiDAR based on phase-coded subcarrier modulation is proposed to mitigate the impact of Doppler-frequency-shift (DFS) from the pseudo-random (PR) pattern. DFS is firstly obtained from the beat signal of the reflected optical carrier and the local optical signal. Then digital DFS compensation is used to mitigate the impact of the DFS from the PR-coded subcarrier. In the demonstration experiment, a 1.25-GHz RF signal is used as the subcarrier which is phase-coded with a 500-Mbit/s M-sequence. The DFS is simulated by an acousto-optic modulator (AOM). The length of fiber is measured, which demonstrate the feasibility of the proposed DFS mitigation method.

关键词： Random modulation lidar phase coding Subcarrier modulation Doppler-frequency-shift

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Using a hybrid encoding method based on the hexagonal resonators to increase the coding capacity of chipless RFID tags

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INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING 2022年第12期32卷 e23474-e23474页

作者： Hayati, Mohsen Majidifar, Sohrab Sobhani, Seyed Naeim Razi Univ Elect Engn Dept Fac Engn Kermanshah Iran Univ Kurdistan Dept Elect Engn Kurdistan Iran

A chipless RFID tag was designed using two hexagonal resonators. By defining a relation for the phases of S-parameters and rotating the resonators around their axes, a senary coding scheme was obtained at the resonant frequency. The designed resonator was able to generate six different codes using six different phase parameters at 3.03 GHz. While the conventional binary ("0" and "1") coding of ordinary tags makes minimal use of bandwidth capacity, the senary coding in the proposed design allowed the use of a larger bandwidth capacity. Requiring much fewer resonators for generating more codes, the proposed technique leads to significantly smaller tags. Using the proposed tag with two resonators, 6(2) = 36 different codes can be generated;more generally, an n-resonator tag of the proposed type can create 6(n) different codes.

关键词： chipless RFID hexagonal resonator phase coding size reduction S-parameters

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Flexible beamforming using transmission-type coding metasurface

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JOURNAL OF PHYSICS D-APPLIED PHYSICS 2022年第34期55卷 345006-345006页

作者： Yang, Jianfeng Chen, Juan Quan, Lei Chen, Xiaoming Shi, Hongyu Liu, Yajun Xue, Wei Xi An Jiao Tong Univ Sch Informat & Commun Engn Xian 710049 Peoples R China Xi An Jiao Tong Univ Shenzhen Res Sch Shenzhen 518000 Peoples R China Xidian Univ Sch Aerosp Sci & Technol Xian 710126 Peoples R China Baoji Univ Arts & Sci Coll Phys & Optoelect Technol Baoji 721016 Peoples R China Northwestern Polytech Univ Sch Elect & Informat Xian 710072 Peoples R China

The emergence and rapid development of metasurfaces have paved the way towards arbitrarily manipulating electromagnetic (EM) waves through amplitude and phase control. However, most real time manipulations were realized in reflection-type metasurfaces depending on phase control. Shaping transmitted fields with metasurface dynamically is still lacking to date. Herein, we propose a strategy combining active transmission amplitude control with phase coding to achieve excellent ability of tailoring the transmitted field patterns dynamically in microwave regime. The metasurface consists of a binary phase coding part on the bottom and an amplitude control part with loaded PIN diodes on the top. When biasing the diodes with variable voltage, active transmission amplitude control is obtained for specific phase coding units without affecting the others. Through phase coding and active amplitude control, manipulating the radiated EM waves on two degrees of freedom is realized. Dynamic beamforming on two coding schemes with this method is exhibited to the demonstrate the manipulation mechanism. The experiment results show good agreements with the theoretical predictions and numerical simulations, hence confirm the proposed concept. In addition, the elaborately designed bias network makes the metasurface polarization-insensitive. This work adds a convenient and feasible way for dynamic EM manipulation and can found new applications, such as reconfigurable beam emitter for adaptive communication and radar systems.

关键词： phase coding amplitude control PIN diodes metasurface

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All-Optical Windowed Binary phase-Coded Microwave Waveform Generation

All-Optical Windowed Binary Phase-Coded Microwave Waveform G...

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International Topical Meeting on Microwave Photonics (MWP)

作者： Hu, Yang Chan, Erwin Hoi Wing Wang, Xudong Feng, Xinhuan Bai-Ou Guan Yao, Jianping Jinan Univ Inst Photon Technol Guangzhou Peoples R China Charles Darwin Univ Coll Engn IT & Environm Darwin NT Australia Univ Ottawa Microwave Photon Res Lab Ottawa ON Canada

ISBN: (纸本)9781665426107

An approach to all-optical windowed binary phase-coded microwave waveform generation is proposed and demonstrated. An optical double sideband plus carrier (DSB+C) signal with the carrier and the two sidebands being orthogonally polarized is generated by a dual-polarization quadrature phase shift keying (DP-QPSK) modulator, with the generated signal sent to a phase modulator (PM). The PM can support phase modulation in two orthogonal polarization directions. The phase-modulated signals are projected to one polarization direction and detected at a photodetector (PD). Switching the polarity of the coding signal, a pi phase shift is introduced. In addition, the amplitude of the generated signal is dependent on the amplitude of the input coding signal. Thus, a windowing function can be applied to the generated waveform by using a windowed input phase coding signal, to suppress the sidelobes in the spectrum of the generated microwave signal. The key features of the proposed waveform generator include all-optical generation without the need of electrical components and optical filters, thus ensuring a wide operating frequency range. Experimental results show that, using a Gaussian windowed 64-bit pseudorandom binary sequence (PRBS) coding signal, a microwave phase-coded microwave waveform is generated with the sidelobes of the spectrum largely suppressed to below the system noise floor and a pulse compression ratio (PCR) as large as 133.

关键词： Microwave photonics phase coding photonic signal generation pulse compression DP-QPSK modulator

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Multi-phase initial ranging process for OFDMA systems: improved dynamic threshold-based multi-user detection approach

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IET COMMUNICATIONS 2020年第13期14卷 2130-2140页

作者： Naveen, Kolihalli Narasaiah Ramesha, Kenchappa Dr Ambedkar Inst Technol Dept Elect & Commun Engn Bengaluru Karnataka India Dr Ambedkar Inst Technol Dept Elect & Instrumentat Engn Bengaluru Karnataka India

Initial ranging (IR) is a process of performing power adjustment, timing offset estimation, and synchronisation between the base station (BS) and all users. It plays a vital role in mobile WiMAX standard, which establishes a communication link between BS and ranging subscriber stations (RSSs). Since RSS is located far away from the BS and uplink signal is corrupted by noise, the IR process becomes inferior. Thus, the authors propose an improved dynamic threshold-based IR method comprising three phases: (i) code detection phase, (ii) filtering phase, and (iii) parameter estimation phase. In the first two phases, the received signal is pre-processed to eliminate noise and unselected codes from the codeset by employing adaptive filter and weight-based code detection method. Then, the noise-free signal is considered for the final phase, which improves accuracy. The iterative expectation maximisation algorithm is involved in the estimation of channel coefficient and timing offset. All possible active paths are detected by setting a dynamic threshold value for each channel by the enhanced dynamic threshold method. For all active channels, round trip delay, and power level are estimated by considering particular channel coefficient and timing offset. Extensive simulation of proposed work shows considerable improvements in performance.

关键词： multiuser detection frequency division multiple access adaptive filters expectation-maximisation algorithm OFDM modulation parameter estimation phase coding signal denoising channel estimation OFDMA systems base station mobile WiMAX standard ranging subscriber stations filtering phase parameter estimation phase received signal noise-free signal weight-based code detection method enhanced dynamic threshold method channel coefficient unselected code detection phase multiphase initial ranging process RSS timing offset estimation synchronisation communication link iterative expectation maximisation algorithm dynamic threshold-based IR method dynamic threshold-based multiuser detection approach

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A recruitment through coherence theory of working memory

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PROGRESS IN NEUROBIOLOGY 2023年第1期228卷 102491页

作者： Comeaux, Phillip Clark, Kelsey Noudoost, Behrad Univ Utah Dept Biomed Engn 36 S Wasatch Dr Salt Lake City UT 84112 USA Univ Utah Dept Ophthalmol & Visual Sci 65 Mario Capecchi Dr Salt Lake City UT 84132 USA

The interactions between prefrontal cortex and other areas during working memory have been studied for decades. Here we outline a conceptual framework describing interactions between these areas during working memory, and review evidence for key elements of this model. We specifically suggest that a top-down signal sent from prefrontal to sensory areas drives oscillations in these areas. Spike timing within sensory areas becomes locked to these working-memory-driven oscillations, and the phase of spiking conveys information about the representation available within these areas. Downstream areas receiving these phase-locked spikes from sensory areas can recover this information via a combination of coherent oscillations and gating of input efficacy based on the phase of their local oscillations. Although the conceptual framework is based on prefrontal interactions with sensory areas during working memory, we also discuss the broader implications of this framework for flexible communication between brain areas in general.

关键词： Working memory Feedback Communication Coherence Oscillations phase coding

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Signal Simulation of Dual-Polarization Weather Radar and Its Application in Range Ambiguity Mitigation

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ATMOSPHERE 2022年第3期13卷 432-432页

作者： Dai, Shaojun Li, Xuehua Bu, Zhichao Chen, Yajun He, Jianxin Li, Minghua Xiong, Maojie Chengdu Univ Informat Technol Coll Elect Engn Chengdu 610225 Peoples R China China Meteorol Adm Key Lab Atmospher Sounding Chengdu 610225 Peoples R China China Meteorol Adm Meteorol Observat Ctr Beijing 100081 Peoples R China Meteorol Observat Ctr Inner Mongolia Meteorol Serv Hohhot 010051 Peoples R China

In this paper, a dual-polarization weather radar echo signal simulation method is proposed for the evaluation of the performance enhancement of dual-polarization weather radar systems, the optimization of signal processing algorithms and the improvement of scanning strategies. The actual weather radar base data are used in the simulation as the reference weather scene, which avoids using a complex algorithm for weather modeling. Moreover, based on radar weather equations, the radar system parameters are added into the radar echo signal modeling to establish the relationship between the simulated echo signal and radar system. As a result, the final simulated echo signal not only shows both the time and frequency domain characteristics of the weather target, but also includes the effects of the important performance of the dual-polarization weather radar system. In addition, to evaluate the performance of range ambiguity mitigation using phase coding and batch working modes, two different simulation methods for the radar signal are established on the method above;one is for batch working mode with long-PRT (pulse repetition time) and short-PRT transmission and receiving, and the other is for phase-coded mode with phase-coded transmission and phase-uncoded receiving. Under the same weather scene, the observation of these two different methods of range ambiguity mitigation are simulated and compared. Results show that the performance of the phase coding mode for mitigating range ambiguity is better than that of the batch mode. Obviously, the simulation method can be used to directly show the observation of different algorithms for mitigation range ambiguity under the same weather process, and quickly compare and evaluate the algorithm's performance, which is not possible for real radars.

关键词： dual-polarization echo simulation range ambiguity batch model phase coding

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