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Multiparty Quantum Remote Secret Conference
LI Xi-Han, LI Chun-Yan, DENG Fu-Guo, , ZHOU Ping, LIANG Yu-Jie, ZHOU Hong-Yu,
Chin. Phys. Lett. 2007, 24 (1):
23-26
.
We present two schemes for multiparty quantum remote secret conference in which each legitimate conferee can read out securely the secret message announced by another, but a vicious eavesdropper can get nothing about it. The first one is based on the same key shared efficiently and securely by all the parties with reenberger--Horne--Zeilinger (GHZ) states, and each conferee sends his secret message to the others with one-time pad crypto-system. The other one is based on quantum encryption with a quantum key, a sequence of GHZ states shared among all the conferees and used repeatedly after confirming their security. Both these schemes are optimal as their intrinsic efficiency for qubits approaches the maximal value.
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Demonstration of a Sagnac-Type Cold Atom Interferometer with Stimulated Raman Transitions
WANG Ping, , LI Run-Bing, , YAN Hui, , WANG Jin, ZHAN Ming-Sheng,
Chin. Phys. Lett. 2007, 24 (1):
27-30
.
Cold-matter-wave Sagnac interferometers possess many advantages over their thermal atomic beam counterparts when they are used as precise inertial sensors. We report a realization of a Sagnac-type interferometer with cold atoms. Cold rubidium atoms are prepared in a magneto-optical trap and are pushed by resonant laser pulse to form slow atomic beam. In the interference region, atomic wave packets are coherently manipulated using π/2-π-π/2 Raman pulse sequences. Interference fringes with maximum contrast of 37% are observed experimentally.
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Different Types of Synchronization in Time-Delayed Systems
FENG Cun-Fang, ZHANG Yan, WANG Ying-Hai
Chin. Phys. Lett. 2007, 24 (1):
50-53
.
We investigate different types of synchronization between two unidirectionally nonlinearly coupled identical delay-differential systems related to optical bistable or hybrid optical bistable devices. This system can represent some kinds of delay-differential models, i.e. Ikeda model, Vallée model, sine-square model, Mackey--Glass model, and so on. We find existence and sufficient stability conditions by theoretical analysis and test the correctness by numerical simulations. Lag, complete and anticipating synchronization are bserved, respectively. It is found that the time-delay system can be divided into two parts, one is the instant term and the other is the delay term. Synchronization between two identical chaotic systems can be derived by adding a coupled term to the delay term in the driven system.
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Phase Transition of FeS in Terms of In-Situ Resistance Measurement
LI Ming, GAO Chun-Xiao, ZHANG Dong-Mei, HE Chun-Yuan, HAO Ai-Min, HUANG Xiao-Wei, YU Cui-Ling, LI Yan-Chun,
LI Xiao-Dong, LIU Jing, ZOU Guang-Tian
Chin. Phys. Lett. 2007, 24 (1):
54-56
.
Electrical properties of stoichiometric iron sulfide (FeS) are investigated under high pressure with a designed diamond anvil cell. The process of phase transition is reflected by changing the electrical conductivity under high pressure, and the conductivity of FeS with the NiAs structure is found to be much smaller than other phases. Two new phase transitions without structural change are observed at 34.7GPa and 61.3GPa. The temperature dependence of the conductivity is found to be similar to that of a semiconductor when the pressure is higher than 35GPa
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Mechanism of Proton-Induced Reactions on Targets 16O, 27Al, 56Fe, 112Cd, 184W and 208Pb At Ep = 800MeV
OU Li, ZHANG Ying-Xun, LI Zhu-Xia,
Chin. Phys. Lett. 2007, 24 (1):
72-75
.
We investigate the 800MeV proton-induced spallation reactions on various targets by the improved quantum molecular dynamics (ImQMD05) model incorporated with a statistical decay model (SDM). The influence of the nucleon--nucleon effective interaction on proton induced spallation reactions is studied by using different Skyrme interactions. It is found that the low energy part of the neutron double differential cross sections (DDCS), which is mainly contributed from the decay of the excited residue, is influenced by the effective nucleon--nucleon interaction strongly, while the high energy part of neutron DDCS is influenced weakly. Among the Skyrme interactions used in the calculations, the calculation results with SkP give the best agreement with the experimental data.
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Analysis of (1, 2) (1, 3) and (2, 3) Bands in the c3IIu-b3IIg System of P2
WU Ling, ZHENG Li-Juan, KANIKI Kakule, CHEN Yang-Qin, YANG Xiao-Hua
Chin. Phys. Lett. 2007, 24 (1):
90-93
.
We investigate the high resolution absorption spectroscopy of P2 radical, generated in ac glow discharge of PCl3 buffered with helium, using optical heterodyne magnetic rotation enhanced concentration modulation spectroscopy in the visible region. The (1, 2), (1, 3) and (2, 3) bands of c3IIu-b3IIg in the range 16620--17860cm-1 are observed and their 3II2-3II2 subbands are rotationally analysed. A set of effective molecular constants for the Ω=2 component of the states involved are determined.
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Double Electron Processes in Collisions of Partially Stripped Ions Cq+(q=1-4) with Helium
DING Bao-Wei, CHEN Xi-Meng, YU De-Yang, FU Hong-Bin, LIU Zhao-Yuan, SUN Guang-Zhi, LIU Yu-Wen, LU Yan-Xia, XIE Jiang-Shan, DU Juan, GAO Zhi-Min, CHEN Lin, CUI Ying, SHAO Jian-Xiong, HE Zi-Feng, CAI Xiao-Hong
Chin. Phys. Lett. 2007, 24 (1):
94-96
.
The multi-electron processes are investigated for 17.9--120keV/u C1+, 30--323keV/u C2+, 120--438keV/u C3+, 287--480keV/u C4+ incident on a helium target. The cross-section ratios of double electron (DE) process to the total of the single electron (SE) and the double electron process (i.e. SE+DE), the direct double electron (DDI) to the direct single ionization (DSI) as well as the contributions of DDI to DE and of TI to DE are measured using coincidence techniques. The energy and charge state dependences of the measured cross-section ratios are studied and discussed.
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Diode End-Pumped Passively Q-Switched Nd3+:GdVO4 Self-Raman Laser at 1176nm
WANG Bao-Shan, PENG Ji-Ying, MIAO Jie-Guang, LI Yi-Min, HAO Er-Juan, ZHNG Zhe, GAO Lan-Lan, TAN Hui-Ming
Chin. Phys. Lett. 2007, 24 (1):
112-114
.
A compact diode-end-pumped passively Q-switched Nd3+:GdVO4/Cr4+:YAG self-Raman laser at 1176nm is demonstrated. When the T0=80% Cr4+:YAG saturable absorber is inserted into the cavity, the maximum Raman laser output reaches 175mW with 3.8W incident pump power. The optical conversion from incident to the Raman laser is 4.6% and the slope efficiency is 6.5%. The pulse energy, duration, and repetition frequency of the first stokes laser are 4.5μJ, 1.8,ns, and 38.5kHz, respectively. There is trong blue emission (about 350--400nm) can be observed in the d3+:GdVO4 crystal when the process of stimulated Raman scattering occurs, which is induced by the upconversion of the d3+ ions.
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High Efficient C6H12 Raman Laser Enhanced by DCM Fluorescence
WANG Hong-Bo, LIANG Hui-Min, WANG Zhi-Hua, LUO Shi-Rong, YANG Jing-Guo, ZHENG Wan-Guo, WEI Xiao-Feng, HE Shao-Bo, CHEN Yuan-Bin
Chin. Phys. Lett. 2007, 24 (1):
119-122
.
We report the first-order Stokes output (wavelength of 627.6nm) from C6H12 enhanced by DCM dye fluorescence with high energy conversion efficiency of 47.9%, quantum conversion efficiency of 56.5%. To our knowledge, it is the highest conversion efficiency of stimulated Raman scattering obtained from liquid Raman laser. A 532nm frequency doubled Nd:YAG laser with 8Hz repetition rate is employed as the pump source, and the enhancement medium is DCM dye solution in ethanol. The conversion efficiencies at various pump energies and various pump repetition rates are measured and analysed. The enhancement mechanism of SRS together with its potential application is discussed.
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New Mechanism for Enhancing Ash Removal Efficiency and Reducing Tritium Inventory
LI Cheng-Yue, DENG Bai-Quan, YAN Jian-Cheng
Chin. Phys. Lett. 2007, 24 (1):
155-157
.
A new mechanism is suggested to suppress ash particle back streams in the divertor region of our fusion experimental breeder (FEB) reactor for enhancing the ash removal efficiency and reducing the tritium inventory by applications of the nonlinear effect of high power rf ponderomotive force potential which reflects the plate-released and re-ionized He+ back to the plate. Meanwhile, the potential does not hinder α particles, which are coming from scraping of the layer, flowing to the target plate. However, it does stop tritium ions flowing to the target. Based on the FEB design parameters, our calculations have shown that the ash removal efficiency can be improved by as much as 40% if the parallel component of rf field 150--200V/cm is applied to the location at a perpendicular distance L=20cm apart from the plate and the plate-recycling neutral helium atom energy is about 0.75eV, at the same time, the tritium inventory can be reduced to some extent.
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Structural Transition of Gd2O3:Eu Induced by High Pressure
CHEN Hai-Yong, HE Chun-Yuan, GAO Chun-Xiao, ZHANG Jia-Hua, GAO Shi-Yong, LU Hong-Liang, NIE Yan-Guang, LI Dong-Mei, KAN Shi-Hai, ZOU Guang-Tian
Chin. Phys. Lett. 2007, 24 (1):
158-160
.
The structural transition of bulk and nano-size Gd2O3:Eu are studied by high pressure energy disperse x-ray diffraction (XRD) and high pressure photoluminescence. Our results show that in spite of different size of Gd2O3 particles, the cubic structure turns into a possible hexagonal one above 13.4GPa. When the pressure is released, the sample reverses to the monoclinic structure. No cubic structure presents in the released samples. That is to say, the compression and relaxation of the sample leads to the cubic Gd2O3:Eu then turns into the monoclinic one.
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Magnetic-Field-Induced Semimetal-Insulator-like Transition in Highly Oriented Pyrolitic Graphite
WANG Zhi-Ming, XING Ding-Yu, ZHANG Shi-Yuan, XU Qing-Yu, Margriet VanBael, DU You-Wei
Chin. Phys. Lett. 2007, 24 (1):
199-202
.
We report the extraordinarily large positive magnetoresistances (MR, 69400% at 4.5K under a magnetic field of 8.15T), de Hass--van Alphen oscillations effect at 10K and the semimetal-insulator-like transition in a wide range of temperature in highly oriented pyrolitic graphite (HOPG). Besides a dominating ordinary MR (OMR) mechanism in the free-electron mode, it is realized from qualitative analysis that the Coulomb interacting quasiparticles within graphite layers play some roles. However it is difficult to associate the transition with thesimple OMR theory. In order to investigate the possible origins of the transition, further analysis is carried out. It is revealed that the magnetic-field-induced behaviour is responsible for the semimetal-insulator-like transitions in HOPG.
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Room-Temperature Ferromagnetism of Co-Doped CeO2 Thin Films on Si(111) substrates
SONG Yuan-Qiang, ZHANG Huai-Wu, WEN Qi-Ye, LI Yuan-Xun, John Q. Xiao
Chin. Phys. Lett. 2007, 24 (1):
218-221
.
Using Co2O3 as the Co source, doped cerium oxide thin films with the composition of Ce0.97Co0.03O2-δ (CCO) are deposited on Si(111) and glass substrates by pulse laser deposition technique. X-ray diffraction reveals that CCO films with (111) preferential orientation are grown on Si, while the film on glass is polycrystalline with nanocrystal. X-ray photoelectron spectroscopy shows that the Co displaces the Ce atom and exists in high spin state rather than low spin state, which contributes to the room-temperature ferromagnetism confirmed by vibration sample magnetometer. Films on Si and glass are different in ferromagnetism, which is believed to be induced by different film microstructures. Based on these results, the possible ferromagnetism in this insulating film is discussed. Anyway, successful fabrication of CCO films with room-temperature ferromagnetism on Si substrates is of great importance in both technological and theoretical aspects.
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Magnetic Force Microscopy Study of Alternate Sputtered (001) Oriented L10 Phase FePt Films
XIA Ai-Lin, CAO Jiang-Wei, TONG Liu-Niu, WEI Fu-Lin, YANG Zheng, HAN Bao-Shan
Chin. Phys. Lett. 2007, 24 (1):
222-225
.
We present a magnetic force microscopy study of alternate sputtered (001) oriented L10 phase FePt films. It is found that the root-mean-square value of phase shift of magnetic force images, (ΔФ)rms, can be used to characterize the perpendicular anisotropy for a series of specimens. Therefore, the considerable improvement of the perpendicular anisotropy after post-annealing can be characterized. In addition, the magnetic properties, magnetic and crystalline microstructures before and after post-annealing are compared for the typical [Fe5nmPt5nm]10 film with substrate temperature Ts=500°C, single layer thickness d=5nm and total layer thickness D=100nm to confirm the effect of post-annealing on improving the perpendicular anisotropy for Fe--Pt films.
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Field Emission Enhancement of Carbon Nanotubes by Surface Modification
YONG Zhen-Zhong, GONG Jin-Long, WANG Zhen-Xia, ZHU Zhi-Yuan, HU Jian-Gang, PAN Qiang-Yan
Chin. Phys. Lett. 2007, 24 (1):
233-235
.
By employing a multi-walled carbon nanotube (MWCNT) film as the substrate, we obtain Fe tipped carbon nanorods or carbon nanoparticles grown on the outer walls of MWCNTs by combining sputtering deposition of Fe films and rf plasma enhanced chemical vapour deposition at high temperature. Scanning electron microscopy and high-resolution transmission electron microscopy are used to examine the structure of carbon nanorods and carbon nanoparticles. In addition, the formation mechanism is discussed briefly. The electron field emission tests indicate that the turn-on field (at 10μA/cm2) of the treated MWCNT films decreases from 2.4V/μm to 0.79V/μm and the field emission current is relatively stable. The enhanced field enhancement factor, increasing emission densities coming from the grown nanorods and nanoparticles, and H terminated by H plasma all are responsible for the enhancement of the field enhancement factor.
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Growth and Characterization of Trumpet-Shaped ZnO Microtube Arrays on Si Substrates
LI Meng-Ke, WANG De-Zhen, SHI Feng, DING Sheng, JIN Hong
Chin. Phys. Lett. 2007, 24 (1):
236-239
.
Aligned trumpet-shaped zinc oxide microtube arrays have been successfully prepared on silicon (100) substrates via the chemical vapour deposition method with a mixture of ZnO and active carbon powders as reactants. The results show that two types of trumpet-shaped ZnO microtubes can be obtained. A plausible growth mechanism based on the studies of scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), and room-temperature photoluminescence spectroscopy is proposed and discussed. The initial metastable zinc-rich ZnOx embryos play a key role in the formation of trumpet-shaped ZnO microtubes. On the different surfaces of metastable zinc-rich ZnOx (x<1), embryos exhibit different stabilities and resistivities to oxidation; these tiny embryos are gradually extended with different growing rates along the directions of its long axis and circular boundary around its oxide shell. Just this special reason creates the formation of trumpet-shaped microtubes and results in the inerratic and imperfect hexagonshaped cross section that appears. Moreover, the analytical results also show that the as-synthesized ZnO microtube arrays can exhibit better room-temperature photoluminescence behaviour.
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Effect of III/V Ratio of HT-AlN Buffer Layer on Polarity Selection and Electrical Quality of GaN Films Grown by Radio Frequency Molecular Beam Epitaxy
ZHONG Fei, QIU Kai, LI Xin-Hua, YIN Zhi-Jun, XIE Xin-Jian, WANG Yang, JI Chang-Jian, CAO Xian-Cun, HAN Qi-Feng, CHEN Jia-Rong, WANG Yu-Qi
Chin. Phys. Lett. 2007, 24 (1):
240-243
.
We investigate the effect of Al/N ratio of the high temperature (HT) AlN buffer layer on polarity selection and electrical quality of GaN films grown by radio frequency molecular beam epitaxy. The results show that low Al/N ratio results in N-polarity GaN films and intermediate Al/N ratio leads to mixed-polarity GaN films with poor electrical quality. GaN films tend to grow with Ga polarity on Al-rich AlN buffer layers. GaN films with different polarities are confirmed by in-situ reflection high-energy electron diffraction during the growth process. Wet chemical etching, together with atomic force microscopy, also proves the polarity assignments. The optimum value for room-temperature Hall mobility of the Ga-polarity GaN film is 703cm2/V.s, which is superior to the N-polarity and mixed-polarity GaN films.
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Chalcogenide Random Access Memory Cell with Structure of W Sub-Microtube Heater Electrode
LIU Bo, FENG Gao-Ming, WU Liang-Cai, SONG Zhi-Tang, LIU Qi-Bin, FENG Song-Lin, CHEN Bomy
Chin. Phys. Lett. 2007, 24 (1):
262-264
.
In order to reduce the reset current of chalcogenide random access memory, a W sub-microtube heater electrode with outer/inner diameter of 260/100nm, which was fabricated with standard 0.18-μm echnology, is proposed for the first time to achieve a reset current of about 0.5mA. The reasons may be that sub-microtube increases the number of electrode edge and thermal efficiency is improved greatly because the thermal density on the edge of sub-microtube electrode is generally the highest.
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Topological Effects on the Performance of Transportation Networks
ZHAO Xiao-Mei, GAO Zi-You
Chin. Phys. Lett. 2007, 24 (1):
283-286
.
We investigate the influence of the network topology on the performance (characterized by the total system cost and maximal traffic volume) of transportation networks, where the weights are not static (constant), but dynamic (a function of the flow on the link). Four classes of networks are used in the simulation, including regular networks, random networks, small-world networks and scale-free networks. The initial simulation results show that topologies play important roles on the performance of transportation networks, and random networks have better performance than other networks. Also, we find that there are distinct difference of the link flow distribution for various networks in both the distribution function form and the span between the minimum and the maximum of the link flow, explaining the difference of the performance among distinct networks. These findings will be useful in network design problems of transportation systems.
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Phase Transition and EOS of Marmatite (Zn0.76Fe0.23S) up to 623K and 17GPa
JIANG Xi, ZHOU Wen-Ge, XIE Hong-Sen, LIU Yong-Gang, FAN Da-Wei, LIU Jing, LI Yan-Chun, LUO Chong-Ju, MA Mai-Ning
Chin. Phys. Lett. 2007, 24 (1):
287-290
.
In situ energy dispersive x-ray diffraction for natural marmatite (Zn0.76Fe0.23S) is performed up to 17.7GPa and 623K. It is fitted by the Birch--Murnaghan equation of state (EOS) that K0 and α0 for marmatite are 85(3)GPa and 0.79(16)×10-4K-1, respectively. Fe2+ isomorphic replacing to Zn2+ in natural crystal is responsible for high bulk modulus and thermal expansivity of marmatite. Temperature derivative of bulk modulus (∂K/∂T)P for marmatite is fitted to be -0.044(23)GPaK-1. The unambiguous B3--B1 phase boundaries for marmatite are determined to be Pupper(GPa)=15.50-0.016 T(°C) and Plower (GPa)=9.94--0.012T(°C) at 300--623K.
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82 articles
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