作者机构：
[Zhang, Deng-Yu; Wang, Xin-Wen; Tang, Shi-Qing; Xie, Li-Jun] Hengyang Normal Univ, Dept Phys & Elect Informat, Hengyang 421008, Peoples R China.;[Yang, Guo-Jian] Beijing Normal Univ, Dept Phys, Beijing 100875, Peoples R China.
通讯机构：
[Wang, Xin-Wen] H;Hengyang Normal Univ, Dept Phys & Elect Informat, Hengyang 421008, Peoples R China.
摘要：
Remote information concentration (RIC) in d-level systems (qudits) is studied. It is shown that the quantum information initially distributed in three spatially separated qudits can be remotely and deterministically concentrated to a single qudit via an entangled channel without performing any global operations. The entangled channel can be different types of genuine multipartite pure entangled states which are inequivalent under local operations and classical communication. The entangled channel can also be a mixed entangled state, even a bound entangled state which has a similar form to the Smolin state, but has different features from the Smolin state. A common feature of all these pure and mixed entangled states is found; i.e., they have d2 common commuting stabilizers. The differences of qudit-RIC and qubit-RIC ( d=2) are also analyzed.
作者机构：
[Xia M.; Yang K.] Wuhan National Laboratory for Optoelectronics, College of Optoelectronics Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China;Department of Physics and Electronic Information Science, Hengyang Normal University, Hengyang, 421008, China;[Tan J.] Wuhan National Laboratory for Optoelectronics, College of Optoelectronics Science and Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China, Department of Physics and Electronic Information Science, Hengyang Normal University, Hengyang, 421008, China
通讯机构：
[Kecheng Yang] W;Wuhan National Laboratory for Optoelectronics, College of Optoelectronics Science and Engineering, Huazhong University of Science and Technology, Wuhan, China
摘要：
Light emitting diode (LED) is one of the most important light sources in the 21st century and has broad prospects in the illumination. Currently, the white LED is used not only for illumination, but also for transmission data. A new technique referred as visible light communication (VLC) is rapidly growing in optical communication. In order to enhance the performance of the communication link, we present optical multiple input and multiple output (MIMO) communication system to achieve high data rate, which can mitigate the shadow effect of indoor communication. Moreover, the MIMO will bring about multi-path effect, which causes inter-symbol interference (ISI) to degrade the performance of the link. Hence, an adaptive equalization technique has been used in the receiver system, which can reduce the ISI when the system is determined to receive symbol. Finally, we have simulated the MIMO system with adaptive equalization. The simulation results show significant improvement in the transmission rate using on off keying (OOK) and the average signal to noise ratio (SNR) in this channel has increased 13.5 dB after equalization.
通讯机构：
[Deng, Xiaohui] H;Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Hengyang 421008, Peoples R China.
关键词：
Thermodynamic properties;Quasiharmonic approximation;Lattice dynamics;Density functional theory
摘要：
The finite-temperature density functional theory and the quasiharmonic approximation are adopted to investigate thermodynamics properties of hexagonal osmium. By varying lattice volume, the anharmonic effect is part considered in present work. Phonon frequencies calculations are performed from density functional perturbation theory (DFPT). By fitting the total free energy (including both electronic and vibrational parts) to equation of states at different temperatures, some classical thermodynamic quantities and their pressure and temperature dependences are investigated systematically. The results are in good agreement with the available experimental and theoretical data.Research Highlights► The finite-temperature DFT and QHA were adopted. ► Thermodynamic properties were investigated systematically. ► CV reaches a constant (∼3 R) with T approaching to the ΘD. ► CP shows an approximate linear behavior beyond the experimental ΘD. ► The temperature dependence on γ is small.
作者机构：
[龙文] Guizhou Key Laboratory of Economics System Simulation, College of Finance and Economics, Guiyang 550004, Guizhou, China;[李山春; 梁昔明; 龙文] School of Information Science and Engineering, Central South University, Changsha 410083, Hunan, China;[龙祖强] Department of Physics and Electronic Information Science, Hengyang Normal College, Hengyang 421008, Hunan, China
通讯机构：
Guizhou Key Laboratory of Economics System Simulation, College of Finance and Economics, China
通讯机构：
[Wang, Xin-Wen] H;Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Hengyang 421008, Peoples R China.
摘要：
We propose a scheme for multiparty hierarchical quantum-information splitting (QIS) with a multipartite entangled state, where a boss distributes a secret quantum state to two grades of agents asymmetrically. The agents who belong to different grades have different authorities for recovering the boss's secret. Except for the boss's Bell-state measurement, no nonlocal operation is involved. The presented scheme is also shown to be secure against eavesdropping. Such a hierarchical QIS is expected to find useful applications in the field of modern multipartite quantum cryptography.
关键词：
Density-functional theory;Doping;Electronic band structure;Graphene
摘要：
A pathway to open the band gap of graphene by p-n codoping is presented according to the first principles study. Two models are used: Lithium adsorbed on Boron-doped graphene (BC) and Boron-Nitrogen (B/N) codoping into graphene. The stability of Lithium adsorbed on BC is firstly analyzed, showing that the hollow site is the most stable configuration, and there is no energy barrier from some metastable configurations to a stable one. After the p-n codoping, the electronic structures of graphene are modulated to open a band gap with width from 0.0 eV to 0.49 eV, depending on the codoping configurations. The intrinsic physical mechanism responsible for the gap opening is the combination of the Boron atom acting as hole doping and Nitrogen (Lithium) as electron doping. (C) 2011 Elsevier B.V. All rights reserved.
