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A hybrid quantum encoding algorithm of vector quantization for image compression 被引量:4
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作者 庞朝阳 周正威 郭光灿 《Chinese Physics B》 SCIE EI CAS CSCD 2006年第12期3039-3043,共5页
Many classical encoding algorithms of vector quantization (VQ) of image compression that can obtain global optimal solution have computational complexity O(N). A pure quantum VQ encoding algorithm with probability... Many classical encoding algorithms of vector quantization (VQ) of image compression that can obtain global optimal solution have computational complexity O(N). A pure quantum VQ encoding algorithm with probability of success near 100% has been proposed, that performs operations 45√N times approximately. In this paper, a hybrid quantum VQ encoding algorithm between the classical method and the quantum algorithm is presented. The number of its operations is less than √N for most images, and it is more efficient than the pure quantum algorithm. 展开更多
关键词 vector quantization Grover's algorithm image compression quantum algorithm
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An Efficient Information Hiding Scheme Based on Closest Paired Tree Structure Vector Quantization 被引量:1
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作者 Zhi-Hui Wang Chin-Chen Chang Ting-Yu Lin 《Journal of Electronic Science and Technology》 CAS 2013年第1期15-19,共5页
Information hiding schemes based on vector quantization (VQ) usually require lengthy VQ encoding and decoding processes. In this paper, we propose an efficient information hiding method based on closest paired tree ... Information hiding schemes based on vector quantization (VQ) usually require lengthy VQ encoding and decoding processes. In this paper, we propose an efficient information hiding method based on closest paired tree structure vector quantization (CPTSVQ). The simulation result shows that the execution time of the proposed scheme is much shorter than that attained by previous approaches. 展开更多
关键词 Digital image information hiding tree structure vector quantization vector quantization.
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Lattice Vector Quantization Applied to Speech and Audio Coding 被引量:1
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作者 Minjie Xie 《ZTE Communications》 2012年第2期25-33,共9页
Lattice vector quantization (LVQ) has been used for real-time speech and audio coding systems. Compared with conventional vector quantization, LVQ has two main advantages: It has a simple and fast encoding process,... Lattice vector quantization (LVQ) has been used for real-time speech and audio coding systems. Compared with conventional vector quantization, LVQ has two main advantages: It has a simple and fast encoding process, and it significantly reduces the amount of memory required. Therefore, LVQ is suitable for use in low-complexity speech and audio coding. In this paper, we describe the basic concepts of LVQ and its advantages over conventional vector quantization. We also describe some LVQ techniques that have been used in speech and audio coding standards of international standards developing organizations (SDOs). 展开更多
关键词 vector quantization lattice vector quantization speech and audio coding transform coding
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In situ calibrated angle between the quantization axis and the propagating direction of the light field for trapping neutral atoms
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作者 郭瑞军 何晓东 +7 位作者 盛诚 王坤鹏 许鹏 刘敏 王谨 孙晓红 曾勇 詹明生 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第2期318-323,共6页
The recently developed magic-intensity trapping technique of neutral atoms efficiently mitigates the detrimental effect of light shifts on atomic qubits and substantially enhances the coherence time. This technique re... The recently developed magic-intensity trapping technique of neutral atoms efficiently mitigates the detrimental effect of light shifts on atomic qubits and substantially enhances the coherence time. This technique relies on applying a bias magnetic field precisely parallel to the wave vector of a circularly polarized trapping laser field. However, due to the presence of the vector light shift experienced by the trapped atoms, it is challenging to precisely define a parallel magnetic field, especially at a low bias magnetic field strength, for the magic-intensity trapping of85Rb qubits. In this work, we present a method to calibrate the angle between the bias magnetic field and the trapping laser field with the compensating magnetic fields in the other two directions orthogonal to the bias magnetic field direction. Experimentally, with a constantdepth trap and a fixed bias magnetic field, we measure the respective resonant frequencies of the atomic qubits in a linearly polarized trap and a circularly polarized one via the conventional microwave Rabi spectra with different compensating magnetic fields and obtain the corresponding total magnetic fields via the respective resonant frequencies using the Breit–Rabi formula. With known total magnetic fields, the angle is a function of the other two compensating magnetic fields.Finally, the projection value of the angle on either of the directions orthogonal to the bias magnetic field direction can be reduced to 0(4)° by applying specific compensating magnetic fields. The measurement error is mainly attributed to the fluctuation of atomic temperature. Moreover, it also demonstrates that, even for a small angle, the effect is strong enough to cause large decoherence of Rabi oscillation in a magic-intensity trap. Although the compensation method demonstrated here is explored for the magic-intensity trapping technique, it can be applied to a variety of similar precision measurements with trapped neutral atoms. 展开更多
关键词 quantization axis trapping laser ANGLE compensating magnetic fields
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Network-Assisted Full-Duplex Cell-Free mmWave Massive MIMO Systems with DAC Quantization and Fronthaul Compression
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作者 Li Jiamin Fan Qingrui +4 位作者 Zhang Yu Zhu Pengcheng Wang Dongming Wu Hao You Xiaohu 《China Communications》 SCIE CSCD 2024年第11期75-87,共13页
In this paper,we investigate networkassisted full-duplex(NAFD)cell-free millimeter-wave(mmWave)massive multiple-input multiple-output(MIMO)systems with digital-to-analog converter(DAC)quantization and fronthaul compre... In this paper,we investigate networkassisted full-duplex(NAFD)cell-free millimeter-wave(mmWave)massive multiple-input multiple-output(MIMO)systems with digital-to-analog converter(DAC)quantization and fronthaul compression.We propose to maximize the weighted uplink and downlink sum rate by jointly optimizing the power allocation of both the transmitting remote antenna units(T-RAUs)and uplink users and the variances of the downlink and uplink fronthaul compression noises.To deal with this challenging problem,we further apply a successive convex approximation(SCA)method to handle the non-convex bidirectional limited-capacity fronthaul constraints.The simulation results verify the convergence of the proposed SCA-based algorithm and analyze the impact of fronthaul capacity and DAC quantization on the spectral efficiency of the NAFD cell-free mmWave massive MIMO systems.Moreover,some insightful conclusions are obtained through the comparisons of spectral efficiency,which shows that NAFD achieves better performance gains than cotime co-frequency full-duplex cloud radio access network(CCFD C-RAN)in the cases of practical limited-resolution DACs.Specifically,their performance gaps with 8-bit DAC quantization are larger than that with1-bit DAC quantization,which attains a 5.5-fold improvement. 展开更多
关键词 cell-free massive MIMO DAC quantization millimeter-wave network-assisted full-duplex
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Linear Discriminant Analysis and Kernel Vector Quantization for Mandarin Digits Recognition
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作者 赵军辉 谢湘 匡镜明 《Journal of Beijing Institute of Technology》 EI CAS 2004年第4期385-388,共4页
Linear discriminant analysis and kernel vector quantization are integrated into vector quantization based speech recognition system for improving the recognition accuracy of Mandarin digits. These techniques increase ... Linear discriminant analysis and kernel vector quantization are integrated into vector quantization based speech recognition system for improving the recognition accuracy of Mandarin digits. These techniques increase the class separability and optimize the clustering procedure. Speaker-dependent (SD) and speaker-independent (SI) experiments are performed to evaluate the performance of the proposed method. The experiment results show that the proposed method is capable of reaching the word error rate of 3.76% in SD case and 6.60 % in SI case. Such a system can be suitable for being embedded in personal digital assistant(PDA), mobile phone and so on to perform voice controlling such as digit dialing, calculating, etc. 展开更多
关键词 linear discriminant analysis kernel vector quantization speech recognition
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A VECTOR BUNDLE VALUED MIXED HARD LEFSCHETZ THEOREM
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作者 Zeng CHEN Guanxiang WANG 《Acta Mathematica Scientia》 2025年第2期514-524,共11页
In this paper,we obtain a vector bundle valued mixed hard Lefschetz theorem.The argument is mainly based on the works of Tien-Cuong Dinh and Viet-Anh Nguyen.
关键词 hard Lefschetz theorem holomorphic vector bundle Hermitian fat vector bundle
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Efficient generation of vectorial terahertz beams using surface-wave excited metasurfaces
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作者 Zhuo Wang Weikang Pan +7 位作者 Yu He Zhiyan Zhu Xiangyu Jin Muhan Liu Shaojie Ma Qiong He Shulin Sun Lei Zhou 《Opto-Electronic Science》 2025年第1期1-11,共11页
On-chip devices for generating pre-designed vectorial optical fields(VOFs)under surface wave(SW)excitations are highly desired in integrated photonics.However,conventional devices are usually of large footprints,low e... On-chip devices for generating pre-designed vectorial optical fields(VOFs)under surface wave(SW)excitations are highly desired in integrated photonics.However,conventional devices are usually of large footprints,low efficiencies,and limited wave-control capabilities.Here,we present a generic approach to design ultra-compact on-chip devices that can efficiently generate pre-designed VOFs under SW excitations,and experimentally verify the concept in terahertz(THz)regime.We first describe how to design SW-excitation metasurfaces for generating circularly polarized complex beams,and experimentally demonstrate two meta-devices to realize directional emission and focusing of THz waves with oppo-site circular polarizations,respectively.We then establish a systematic approach to construct an integrated device via merging two carefully designed metasurfaces,which,under SW excitations,can separately produce pre-designed far-field patterns with different circular polarizations and generate target VOF based on their interference.As a proof of con-cept,we demonstrate experimentally a meta-device that can generate a radially polarized Bessel beam under SW excita-tion at~0.4 THz.Experimental results agree well with full-wave simulations,collectively verifying the performance of our device.Our study paves the road to realizing highly integrated on-chip functional THz devices,which may find many ap-plications in biological sensing,communications,displays,image multiplexing,and beyond. 展开更多
关键词 surface waves vector beam multi-pixel metasurface TERAHERTZ ultrathin and high-efficiency
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Modulation of Bessel-like vector vortex beam using the resonant magneto-optical effect in rubidium vapor
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作者 Yan Ma Xin Yang +4 位作者 Hong Chang Ming-Tao Cao Xiao-Fei Zhang Rui-Fang Dong Shou-Gang Zhang 《Chinese Physics B》 2025年第2期274-280,共7页
The Bessel-like vector vortex beam(BlVVB)has gained increasing significance across numerous applications.However,its practical application is restricted by manufacturing difficulties and polarization manipulation.Thus... The Bessel-like vector vortex beam(BlVVB)has gained increasing significance across numerous applications.However,its practical application is restricted by manufacturing difficulties and polarization manipulation.Thus,the ability to manipulate its degrees of freedom is highly desirable.In this paper,the full-domain polarization modulation of BlVVB within a hot atomic ensemble has been investigated.We begin with the theoretical analysis of the resonant magneto-optical effect of atoms with a horizontal linear-polarized beam and experimentally demonstrate precise manipulation of the polarization state across the entire domain of the BlVVB,achieving an error margin of less than 3°at various cross-sectional points.Our study provides a novel approach for the modulation of BlVVB based on atomic media,which holds potential applications in sensitive vector magnetometers,optical communications,and signal processing. 展开更多
关键词 Bessel-like vector vortex beam resonant magneto-optical effect polarization modulation Rb atomic ensemble
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Rotational symmetry of classical orbits, arbitrary quantization of angular momentum and the role of the gauge field in two-dimensional space 被引量:2
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作者 辛俊丽 梁九卿 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第4期67-73,共7页
We study quantum classical correspondence in terms of the coherent wave functions of a charged particle in two-dimensional central-scalar potentials as well as the gauge field of a magnetic flux in the sense that the ... We study quantum classical correspondence in terms of the coherent wave functions of a charged particle in two-dimensional central-scalar potentials as well as the gauge field of a magnetic flux in the sense that the probability clouds of wave functions are well localized on classical orbits. For both closed and open classical orbits, the non-integer angular-momentum quantization with the level space of angular momentum being greater or less than h is determined uniquely by the same rotational symmetry of classical orbits and probability clouds of coherent wave functions, which is not necessarily 27r-periodic. The gauge potential of a magnetic flux impenetrable to the particle cannot change the quantization rule but is able to shift the spectrum of canonical angular momentum by a flux-dependent value, which results in a common topological phase for all wave functions in the given model. The well-known quantum mechanical anyon model becomes a special case of the arbitrary quantization, where the classical orbits are 2π-periodic. 展开更多
关键词 quantum-classical correspondence ANYON rotational symmetry arbitrary quantization of angular momentum
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Quantization of light energy directly from classical electromagnetic theory in vacuum 被引量:2
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作者 佘卫龙 《Chinese Physics B》 SCIE EI CAS CSCD 2005年第12期2514-2521,共8页
It is currently believed that light quantum or the quantization of light energy is beyond classical physics, and the picture of wave-particle duality, which was criticized by Einstein but has attracted a number of exp... It is currently believed that light quantum or the quantization of light energy is beyond classical physics, and the picture of wave-particle duality, which was criticized by Einstein but has attracted a number of experimental researches, is necessary for the description of light. It is shown in this paper, however, that the quantization of light energy in vacuum, which is the same as that in quantum electrodynamics, can be derived directly from the classical electromagnetic theory through the consideration of statistics based on classical physics. Therefore, the quantization of energy is an intrinsic property of light as a classical electromagnetic wave and has no need of being related to particles. 展开更多
关键词 the nature of light quantization of light energy classical electromagnetic theory consideration of statistics
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s-parameterized Weyl transformation and the corresponding quantization scheme 被引量:2
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作者 王继锁 孟祥国 范洪义 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第1期265-268,共4页
By extending the usual Weyl transformation to the s-parameterized Weyl transformation with s being a real parameter,we obtain the s-parameterized quantization scheme which includes P–Q quantization, Q–P quantization... By extending the usual Weyl transformation to the s-parameterized Weyl transformation with s being a real parameter,we obtain the s-parameterized quantization scheme which includes P–Q quantization, Q–P quantization, and Weyl ordering as its three special cases. Some operator identities can be derived directly by virtue of the s-parameterized quantization scheme. 展开更多
关键词 generalized Wigner transformation s-parameterized quantization scheme
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Mid-infrared supercontinuum generation and its application on all-optical quantization with different input pulses 被引量:1
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作者 Yan Li Xinzhu Sang 《Chinese Physics B》 SCIE EI CAS CSCD 2019年第5期126-133,共8页
Supercontinuum generation(SCG) and its application on all-optical quantization of all-optical analog-to-digital conversions(AOADCs) at the mid-infrared region in an Al GaAs strip waveguide are investigated numerically... Supercontinuum generation(SCG) and its application on all-optical quantization of all-optical analog-to-digital conversions(AOADCs) at the mid-infrared region in an Al GaAs strip waveguide are investigated numerically. The simulation results show that when the parabolic pulse is input, not only broader and higher-coherence SCG is obtained and a higher effective number of bits(ENOB) can be achieved, compared with the input pulse with hyperbolic-secant and Gaussian shaping. A four-bit quantization resolution is achieved along with a signal-to-noise ratio of 24.02 dB and an ENOB of3.99 bit, and the required input peak power is 760 mW. 展开更多
关键词 MID-INFRARED SUPERCONTINUUM generation ALL-OPTICAL quantization
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ADC border effect and suppression of quantization error in the digital dynamic measurement 被引量:3
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作者 白丽娜 刘海东 +7 位作者 周渭 张勇 翟鸿启 崔震健 赵明英 谷小倩 刘蓓玲 黄李贝 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第9期91-97,共7页
The digital measurement and processing is an important direction in the measurement and control field. The quantization error widely existing in the digital processing is always the decisive factor that restricts the ... The digital measurement and processing is an important direction in the measurement and control field. The quantization error widely existing in the digital processing is always the decisive factor that restricts the development and applications of the digital technology. In this paper, we find that the stability of the digital quantization system is obviously better than the quantization resolution. The application of a border effect in the digital quantization can greatly improve the accuracy of digital processing. Its effective precision has nothing to do with the number of quantization bits, which is only related to the stability of the quantization system. The high precision measurement results obtained in the low level quantization system with high sampling rate have an important application value for the progress in the digital measurement and processing field. 展开更多
关键词 quantization error border effect digital converter(ADC)
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Number-phase quantization of a mesoscopic RLC circuit 被引量:1
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作者 Xu Cheng-Lin 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第2期114-116,共3页
With the help of the time-dependent Lagrangian for a damped harmonic oscillator, the quantization of mesoscopic RLC circuit in the context of a number-phase quantization scheme is realized and the corresponding Hamilt... With the help of the time-dependent Lagrangian for a damped harmonic oscillator, the quantization of mesoscopic RLC circuit in the context of a number-phase quantization scheme is realized and the corresponding Hamiltonian operator is obtained. Then the evolution of the charge number and phase difference across the capacity are obtained. It is shown that the number-phase analysis is useful to tackle the quantization of some mesoscopic circuits and dynamical equations of the corresponding operators. 展开更多
关键词 mesoscopic RLC circuit number-phase quantization Lagrangian function
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FLOATING QUANTIZATION EFFECTS ON MULTIRATE SAMPLED-DATA NONLINEAR CONTROL SYSTEMS 被引量:1
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作者 余宏旺 汪志鸣 《Acta Mathematica Scientia》 SCIE CSCD 2007年第3期635-644,共10页
In this article, floating quantization effects on multirate sampled-data control systems are studied. It shows that the solutions of multirate digital feedback control systems with nonlinear plant and with floating qu... In this article, floating quantization effects on multirate sampled-data control systems are studied. It shows that the solutions of multirate digital feedback control systems with nonlinear plant and with floating quantization in the controller are uniformly ultimately bounded if the associated linear systems consisting of linearization of the plant and controller with no quantization are Schur stable. Moreover, it also shows that the difference between the response of multirate digital controllers without quantizers and the same plant with floating quantization in the controllers can be made as small as desired by selecting proper quantization level. 展开更多
关键词 Multirate sampled-data control systems quantization Schur stable uniformly ultimately bounded
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Quantization-Based Robust Image Watermarking Using the Dual Tree Complex Wavelet Transform 被引量:4
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作者 LIU Jinhua SHE Kun 《China Communications》 SCIE CSCD 2010年第4期1-6,共6页
Conventional quantization index modulation (QIM) watermarking uses the fixed quantization step size for the host signal.This scheme is not robust against geometric distortions and may lead to poor fidelity in some are... Conventional quantization index modulation (QIM) watermarking uses the fixed quantization step size for the host signal.This scheme is not robust against geometric distortions and may lead to poor fidelity in some areas of content.Thus,we proposed a quantization-based image watermarking in the dual tree complex wavelet domain.We took advantages of the dual tree complex wavelets (perfect reconstruction,approximate shift invariance,and directional selectivity).For the case of watermark detecting,the probability of false alarm and probability of false negative were exploited and verified by simulation.Experimental results demonstrate that the proposed method is robust against JPEG compression,additive white Gaussian noise (AWGN),and some kinds of geometric attacks such as scaling,rotation,etc. 展开更多
关键词 Image Watermarking quantization IndexModulation Dual Tree Complex Wavelet Transform JPEG Compression
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MODIFIED QUANTIZATION INDEX MODULATION WATERMARKING ADAPTIVE TO CONTRAST MASKING THRESHOLDS
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作者 Wang, Guoxi Ma, Lihong +2 位作者 Yu, Decong Cai, Kang Lu, Hanqing 《China Communications》 SCIE CSCD 2007年第1期75-84,共10页
In this paper,we suggest an adaptive watermarking method to improve both transparence and robustness of quantization index modulation(QIM) scheme. Instead of a fixed quantization step-size,we apply a step-size adapted... In this paper,we suggest an adaptive watermarking method to improve both transparence and robustness of quantization index modulation(QIM) scheme. Instead of a fixed quantization step-size,we apply a step-size adapted to image content in each 8×8 block to make a balance of robust extraction and transparent embedding.The modified step-size is determined by contrast masking thresholds of Watson’s perceptual model.From a normalized crossed-correlation value between the original watermark and the detected watermark,we could observe that our method is robust to attacks of additive white Gaussian noise(AWGN),Salt and Pepper noise and Joint Photographic Experts Group(JPEG) compression than the original QIM.By taking into account the contrast insensitivity and visible thresholds of human visual system,the suggested improvement achieves a maximum embedding strength and an appropriate quantization step-size which is consistent with local values of a host signal. 展开更多
关键词 vector projected WATERMARKING ADAPTIVE quantization index modulation CONTRAST sensitivity MASKING
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Quantization of the double-qubit structure and quantum computation
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作者 梁宝龙 王继锁 《Chinese Physics B》 SCIE EI CAS CSCD 2007年第10期3097-3103,共7页
The quantization scheme of a double-qubit structure with superconducting quantum interference devices (SQUIDs) is given. By introducing unitary matrices and using spectral decompositions, the Hamiltonian operator of... The quantization scheme of a double-qubit structure with superconducting quantum interference devices (SQUIDs) is given. By introducing unitary matrices and using spectral decompositions, the Hamiltonian operator of the system is exactly formulated in compact forms in spin-1/2 notation. A scheme of designing controlled-phase-shift (CPS) gates is also proposed by using this circuit system. 展开更多
关键词 double-qubit quantization spectral decomposition controlled-phase-shift
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Electromagnetic field quantization and input–output relation for anisotropic magnetodielectric metamaterial
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作者 董云霞 刘春颖 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第6期347-352,共6页
A phenomenological quantization of electromagnetic field is introduced in the presence of the anisotropic magnetodi- electric metamaterial. For a single layer structure with the anisotropic metamaterial, input-output ... A phenomenological quantization of electromagnetic field is introduced in the presence of the anisotropic magnetodi- electric metamaterial. For a single layer structure with the anisotropic metamaterial, input-output relations of quantized radiation are derived using the Green-function approach. Based on these relations, the reflectance of the linearly polarized wave through this structure is calculated. The results show that different resonant peaks of reflectance appear for different polarized waves and indicate the use of the anisotropic metamaterial as a reflector for a certain polarized wave. Furthermore it is found that such a structure can realize the resonant gap with the increase of the thickness. Finally the effects of the absorption are considered and we find that the above properties do not change with the introduction of the absorption. 展开更多
关键词 anisotropic metamaterials magnetodielectric quantization electromagnetic field
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