We propose an efficient optical coupler to launch free-space signals into a dielectric dielectric waveguide via plasmonic structures with great field enhancement. A plasmonic concentrator composed of a subwavelength s...
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We propose an efficient optical coupler to launch free-space signals into a dielectric dielectric waveguide via plasmonic structures with great field enhancement. A plasmonic concentrator composed of a subwavelength slit surround by periodic grooves is used to access and collect free-space light. The transmitted light is then unidirectional directed into a dielectric waveguide with a plasmonic Bragg reflector and a directional coupler. The free-space optical coupler is useful as it combines the plasmonic structure for optical signal access in subwavelength scale with the ultra-low loss dielectric waveguide for long-distance signal transmission and processing making use of nonlinearity.
作者：
Yang LiBin LuoHong Guo[]CREAM Group
State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computer Science and Center for Computational Science and Engineering (CCSE) Peking University Beijing 100871 People’s Republic of China
We study the dynamics of two identical atoms resonantly coupled to a single-mode cavity under practical feedback control, and focus on the detection inefficiency. The entanglement is induced to vanish in finite time b...
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We study the dynamics of two identical atoms resonantly coupled to a single-mode cavity under practical feedback control, and focus on the detection inefficiency. The entanglement is induced to vanish in finite time by the inefficiency of detection. Counterintuitively, the asymptotic entanglement and quantum discord can be increased by the inefficiency of detection. The noise of detection triggers the control field to create entanglement and discord when no photons are emitted from the atoms. Furthermore, sudden change happens to the dynamics of entanglement.
This paper proposes and evaluates Self-Organizing Latency-Aware Resource Ensemble (SOLARE), a peer-to-peer self-organizing and self-managing cluster system based upon network coordinates and utility functions. In cont...
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This paper proposes and evaluates Self-Organizing Latency-Aware Resource Ensemble (SOLARE), a peer-to-peer self-organizing and self-managing cluster system based upon network coordinates and utility functions. In contrast to previous works, SOLARE is a fully decentralized clustering algorithm without any central units such as servers, super peers, cluster heads or landmarks. Furthermore, SOLARE allows for adaptability to dynamic network changes by monitoring the utility of a cluster and migrating nodes to other higher-utility clusters when the utility of an existing cluster is low. Quantitative, simulation-driven evaluations show that SOLARE is able to satisfy user demands expressed by utility functions that integrate system parameters in terms of intra cluster latencies and the number of cluster members. Also, we verify the ability of SOLARE to adapt to dynamic network changes through simulation based experiments that consider the number of nodes which migrate into another cluster and average utility value as nodes join SOLARE.
This paper proposes a method for mobile robot exploration based on the idea of frontier exploration which suggests navigating the robot toward the boundaries between free and unknown areas in the map. A global occupan...
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This paper proposes a method for mobile robot exploration based on the idea of frontier exploration which suggests navigating the robot toward the boundaries between free and unknown areas in the map. A global occupancy grid map of the environment is constantly updated, based on which a global frontier map is calculated. Then, a histogram based approach is adopted to cluster frontier cells and score these clusters based on their distance from the robot as well as the number of frontier cells they contain. In each stage of the algorithm, a sub-goal is set for the robot to navigate. A combination of distance transform and A* search algorithms is utilized to generate a plausible path toward the sub-goal through the free space. This way keeping a reliable distance from obstacles is guaranteed while searching for the shortest path toward the sub-goal. When such a path is generated, a B-spline interpolated and smoothed trajectory is produced as the control reference for the mobile robot to follow. The whole process is iterated until no unexplored area remains in the map. The efficiency of the method is shown through simulated and real experiments.
The crossing coupler is introduced to form a microring resonator. The coupling coefficient of the crossing can affect the resonance spectrum significantly based on the model of the coupled mode theory.
The crossing coupler is introduced to form a microring resonator. The coupling coefficient of the crossing can affect the resonance spectrum significantly based on the model of the coupled mode theory.
作者：
Yujie ShenXiang PengJian YangHong Guo[]CREAM Group
State Key Laboratory of Advanced Optical Communication Systems and Networks (Peking University) and Institute of Quantum Electronics School of Electronics Engineering and Computer Science Peking University Beijing 100871 PR China
Source noise affects the security of continuous-variable quantum key distribution (CV QKD) and is difficult to analyze. We propose a model to characterize Gaussian source noise through introducing a neutral party (Fre...
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Source noise affects the security of continuous-variable quantum key distribution (CV QKD) and is difficult to analyze. We propose a model to characterize Gaussian source noise through introducing a neutral party (Fred) who induces the noise with a general unitary transformation. Without knowing Fred’s exact state, we derive the security bounds for both reverse and direct reconciliations and show that the bound for reverse reconciliation is tight.
This paper presents a modern control system for three phase high performance interior permanent magnet motor drives. The control system combines the advantages of vector control and direct torque control and overcomes...
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This paper presents a modern control system for three phase high performance interior permanent magnet motor drives. The control system combines the advantages of vector control and direct torque control and overcomes some of the implementation drawbacks of either of the methods. The system uses a current control loop in connection with a switching table. A brain emotional learning based intelligent controller (BELBIC) is employed in the system which provides excellent performance under different operating conditions. BELBIC is based on the emotion processing mechanism in human's brain providing actions based on sensory inputs and emotional cues. A comprehensive evaluation of an IPM motor performance under the proposed control system proves the effectiveness of the system and its partial superiority over either vector control or direct torque control despite its relatively simple structure.
作者：
李扬郭弘CREAM Group
State Key Laboratory of Advanced Optical Communication Systems and Networks and Institute of QuantumElectronicsSchool of Electronics Engineering and Computer SciencePeking University
The solitonic behaviors of coupled-resonator optical waveguide doped by two-level atoms are studied from a quantum mechanical *** phase space analysis and Galilean invariance,we prove that immobile and moving bright s...
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The solitonic behaviors of coupled-resonator optical waveguide doped by two-level atoms are studied from a quantum mechanical *** phase space analysis and Galilean invariance,we prove that immobile and moving bright soliton can exist in this *** results are helpful for the study of optical communication especially in slow-light engineering.
作者：
Bin LuoHong GuoCREAM Group
State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computer Science Peking University Beijing China
Dispersion properties of an optical medium can be greatly changed using electromagnetically induced transparency (EIT) and other nonlinear effects. Thus, the group velocity of light pulse can be much smaller (greater ...
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Dispersion properties of an optical medium can be greatly changed using electromagnetically induced transparency (EIT) and other nonlinear effects. Thus, the group velocity of light pulse can be much smaller (greater or even negative) than light speed in vacuum, which is called slow (fast) light. Slow and fast light are very useful in optical processing, such as optical buffer, switching, and storage devices. Usually, slow and fast light cannot be generated simultaneously in the same medium. In this paper, we propose applicable level structures to generate controllable slow and fast light simultaneously at two frequencies, with the same polarization.
作者：
周江郭弘CREAM Group
State Key Laboratory of Advanced Optical Communication Systems and Networks and Institute of Quantum Electronics School of Electronics Engineering and Computer Science Peking University
Recently, people begin to analyze the dynamics of an extended system which incorporates two qubits and their respective reservoirs and successfully explain the process of information transmission in Markovian regime [...
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Recently, people begin to analyze the dynamics of an extended system which incorporates two qubits and their respective reservoirs and successfully explain the process of information transmission in Markovian regime [1, 2]. Inspired by their notable results, we study the entanglement dynamics of the composite system via a nonperturbative method [3] with both symmetrical and asymmetrical atom-reservoir couplings. We find that with the introduction of asymmetry, the quantitative criteria for the birth and death phenomena in both Markovian [1] and non-Markovian regime lose their validity. Besides, we investigate an interesting issue that the composite system is composed of a Markovian subsystem and a non-Markovian one.
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