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Efficient Quantum Cryptography Network without Entanglement and Quantum Memory
LI Chun-Yan, LI Xi-Han, DENG Fu-Guo, , ZHOU Ping, LIANG Yu-Jie, ZHOU Hong-Yu,
Chin. Phys. Lett. 2006, 23 (11):
2897-2899
.
An efficient quantum cryptography network protocol is proposed with $d$-dimensional polarized photons, without resorting to entanglement and quantum memory. A server on the network, say Alice, provides the service for preparing and measuring single photons whose initial state are |0>. The users code the information on the single photons with some unitary operations. To prevent the untrustworthy server Alice from eavesdropping the quantum lines, a nonorthogonal-coding technique is used in the process that the quantum signal is transmitted between the users. This protocol does not require the servers and the users to store the quantum states and almost all of the single photons can be used for carrying the information, which makes it more convenient for application than others with present technology. We also discuss the case with a faint laser pulse
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Dynamical Properties of Potassium Ion Channels with a Hierarchical Model
ZHAN Yong, AN Hai-Long, YU Hui, ZHANG Su-Hua, HAN Ying-Rong
Chin. Phys. Lett. 2006, 23 (11):
2906-2908
.
It is well known that potassium ion channels have higher permeability than K ions, and the permeable rate of a single K ion channel is about 108 ions per second. We develop a hierarchical model of potassium ion channel permeation involving ab initio quantum calculations and Brownian dynamics simulations, which can consistently explain a range of channel dynamics. The results show that the average velocity of K ions, the mean permeable time of K ions and the permeable rate of single channel are about 0.92nm/ns, 4.35ns and 2.30× 108ions/s, respectively.
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In-Situ Conductivity Measurement of BaF2 under High Pressure and High Temperature
HAO Ai-Min, GAO Chun-Xiao, LI Ming, HE Chun-Yuan, HUANG Xiao-Wei, ZHANG Dong-Mei, YU Cui-Ling, ZOU Guang-Tian, LI Yan-Chun, LI Xiao-Dong, LIU Jing
Chin. Phys. Lett. 2006, 23 (11):
2917-2919
.
We perform the in-situ conductivity measurement on BaF2 at high pressure using a microcircuit fabricated on a diamond anvil cell. The results show that BaF2 initially exhibits the electrical property of an insulator at pressure below 25GPa, it transforms to a wide energy gap semiconductor at pressure from 25 to 30GPa, and the conductivity increases gradually with increasing pressure from 30GPa. However, the metallization predicted by theoretical calculation at 30--33GPa cannot be observed. In addition, we measure the temperature dependence of the conductivity at several pressures and obtain the relationship between the energy gap and pressure. Based on the experimental data, it is predicted that BaF2 would transform to a metal at about 87GPa and ambient temperature. The conductivity of BaF2 reaches the order of 10-3\Omega-1cm-1 at 37GPa and 2400K, the superionic conduction is not observed during the experiments, indicating the application of pressure elevates greatly the transition temperature of the superionic conduction.
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Holographic Grating Formation in Cationic Photopolymers with Dark Reaction
WEI Hao-Yun, CAO Liang-Cai, GU Claire, XU Zhen-Feng, HE Ming-Zhao, HE Qing-Sheng, HE Shu-Rong, JIN Guo-Fan
Chin. Phys. Lett. 2006, 23 (11):
2960-2963
.
We propose a new formula to describe the dynamics of holographic grating formation under low intensity pulse exposures in cationic photopolymers, in which the dark reaction contributes dominantly to the grating strength. The formula is based on the living polymerization mechanism and the diffusion-free approximation. The analytical solution indicates that the grating formation time depends on the termination rate constant, while the final grating strength depends linearly on the total exposure energy. These theoretical predictions are verified experimentally using the Aprilis HMC-400μm photopolymer. The results can provide guidelines for the control and optimization of the holographic recording conditions in practical applications.
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High-Duty-Cycle Operation of GaAs/AlGaAs Quantum Cascade Laser above Liquid Nitrogen Temperature
LIU Jun-Qi, LIU Feng-Qi, SHAO Ye, LI Lu, GUO Yu, WANG Zhan-Guo, WANG Liang-Chen
Chin. Phys. Lett. 2006, 23 (11):
2968-2971
.
We present a detailed study of λ ~ 9.75μm GaAs/AlGaAs quantum cascade lasers. For a coated 2-mm-long and 40-μm-wide laser, an optical power of 85μW is observed at 95% duty cycle at 80K. At a moderate driving pulse (1kHz and 1% duty cycle), the device presents a peak power more than 20mW even at 120K. At 80K, the fitted result of threshold current densities shows evidence of potential cw operation.
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Structure Dependence of Mode Edges in Photonic Crystal Waveguide with Silicon on Insulator
TANG Hai-Xia, ZUO Yu-Hua, YU Jin-Zhong, WANG Qi-Ming
Chin. Phys. Lett. 2006, 23 (11):
2999-3002
.
The mode edges of photonic crystal waveguide with triangular lattice based on a silicon-on-insulator slab are investigated by combination of the effective index method and the two-dimensional plane wave expansion method. The variations of waveguide-mode edges with the structure parameters of photonic crystal are deduced. When the ratio of the radius of air holes to the lattice constant, r/Λ, is fixed and the lattice constant of photonic crystal, Λ, increases, the waveguide-mode edges shift to longer wavelengths. When Λ is fixed and r/Λ increases, the waveguide-mode edges shift to shorter wavelengths. Additionally, when r/Λ and Λ are both fixed, the radius of the two-row air holes adjacent to the waveguide increases, the waveguide-mode edges shift to shorter wavelengths.
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Modified Richardson Number in Non-Uniform Saturated Moist Flow
YANG Shuai, GAO Shou-Ting
Chin. Phys. Lett. 2006, 23 (11):
3003-3006
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As a useful index, i.e. the Richardson number Ri, is modified in non-uniform saturated moist flow, based on the fact that liquid water is partially dropped out in parcel air. This is more realistic in real moist atmosphere, especially in the rainfall process. The modified Ri presents adequately the influence of numerator, i.e. Brunt--Vaisala frequency (BVF), on instability. Compared to several former formulae generalized by Durran and Klemp, the modified Ri evidently decreases the stability in rainy regions. In theory, the modified BVF and Ri fix the discontinuity of latent heat release in the transition areas between saturated and unsaturated air by introducing the condensation probability function. Furthermore, the diagnostic analysis of the modified Ri validates the rationality of its application in the non-uniform sturated moist process.
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Preparation and Microstructure of Tantalum Nitride Thin Film by Cathodic Arc Deposition
LI Li, NIU Er-Wu, LV Guo-Hua, FENG Wen-Ran, GU Wei-Chao, CHEN Guang-Liang, ZHANG Gu-Ling, FAN Song-Hua, LIU Chi-Zi, YANG Si-Ze
Chin. Phys. Lett. 2006, 23 (11):
3018-3021
.
Tantalum nitride (TaN) thin films are achieved on Si(111) and SS317L substrates by cathodic vacuum arc technique, which is rarely reported in the literature. The crystal structure, composition and surface morphology of the films are characterized by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), auger electron spectroscopy, and atomic force microscopy, respectively. The influence of substrate negative bias on crystal structure, composition, surface morphology of the TaN films is systematically studied. At the substrate bias of 0V and -50V, the amorphous TaN film is obtained. As the bias increases to -100V, cubic TaN phase can be found. Stoichiometric TaN with hexagonal lattice preferred (300) orientation is prepared at a bias of -200V. Combine the XRD and XPS results, the binding energy value of 23.6eV of Ta 4f7/2 is contributed to hexagonal TaN. Compared to other techniques, TaN thin films fabricated by cathodic vacuum arc at various substrate biases show different microstructures.
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Scaling Behaviour of Diffusion Limited Aggregation with Linear Seed
TANG Qiang, TIAN Ju-Ping, YAO Kai-Lun,
Chin. Phys. Lett. 2006, 23 (11):
3033-3036
.
We present a computer model of diffusion limited aggregation with linear seed. The clusters with varying linear seed lengths are simulated, and their pattern structure, fractal dimension and multifractal spectrum are obtained. The simulation results show that the linear seed length has little effect on the pattern structure of the aggregation clusters if its length is comparatively shorter. With its increasing, the linear seed length has stronger effects on the pattern structure, while the dimension Df decreases. When the linear seed length is larger, the corresponding pattern structure is cross alike. The larger the linear seed length is, the more obvious the cross-like structure with more particles clustering at the two ends of the linear seed and along the vertical direction to the centre of the linear seed. Furthermore, the multifractal spectra curve becomes lower and the range of singularity narrower. The longer the length of a linear seed is, the less irregular and nonuniform the pattern becomes.
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Shock Compression and Phase Transitions of Magnesiowüstite (Mg,Fe)O up to Earth’s Lowermost Mantle Conditions
ZHANG Li, GONG Zi-Zheng,
Chin. Phys. Lett. 2006, 23 (11):
3049-3051
.
We report new shock-compression data for polycrystalline (Mg,Fe)O up to 130GPa shock pressures corresponding to Earth’s lowermost mantle conditions. Our data together with the existing shock-wave data of (Mg,Fe)O and its end-members MgO and FeO reveal that the Hugoniot curves of (Mg,Fe)O does not change with varying FeO content for their B1 phase (NaCl-structure) in the pressure--relative-volume plane. The evidence of the volume change within 3% at around 120GPa along the Hugoniot of (Mg0.6, Fe0.4)O is consistent with a structural transition from B1 phase (NaCl cubic) to B8 phase (NiAs-type hexagonal). Such a structural transition of (Mg,Fe)O, if indeed occurs, may in part contribute to the scattering of seismic waves and change in velocity gradient found in the lowermost mantle.
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Fabrication of GaN Nanorods in a Large Scale on Si(111) Substrate by Ammoniating Technique
AI Yu-Jie, XUE Cheng-Shan, SUN Li-Li, SUN Chuan-Wei, ZHUANG Hui-Zhao, WANG Fu-Xue, CHEN Jin-Hua, LI Hong
Chin. Phys. Lett. 2006, 23 (11):
3052-3054
.
GaN nanorods in a large scale have been synthesized on Si (111) substrates by ammoniating Ga2O3/Mg films under flowing ammonia atmosphere at the temperature of 1000°C for 15min. The as-synthesized GaN nanorods are characterized by scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. The results demonstrate that these straight nanorods are hexagonal wurtzite GaN single crystals in diameters ranging from 200nm to 600nm.
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Synthesis of GaN Nanorods by Ammoniating Ga2O3/ZnO Films
XUE Shou-Bin, ZHUANG Hui-Zhao, XUE Cheng-Shan, HU Li-Jun
Chin. Phys. Lett. 2006, 23 (11):
3055-3057
.
Large quantities of GaN nanorods are successfully synthesized on Si(111) substrates by ammoniating the films of Ga2O3/ZnO at 950°C in a quartz tube. The structure, morphology and optical properties of the as-prepared GaN nanorods are studied by x-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, and photoluminescence. The results show that the GaN nanorods have a hexagonal wurtzite structure with lengths of several micrometres and diameters from 80nm to 300nm, which could supply an attractive potential to harmonically incorporate future GaN optoelectronic devices into Si-based large-scale integrated circuits. The growth mechanism is also briefly discussed.
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Thermal Stability and Spectroscopic Properties of Yb3+-Doped New Gallium--Lead--Germanate Glass
XU Shi-Qing, FENG Ai-Ming, ZHANG Li-Yan, ZHAO Shi-Long, WANG Bao-Ling, ZHANG Jue, WANG Wei, BAO Ren-Qiang
Chin. Phys. Lett. 2006, 23 (11):
3069-3071
.
Yb3+-doped new gallium--lead--germanate glass is presented. Thermal stability, spectroscopic and laser performance parameters of the Yb3+-doped new gallium--lead--germanate glass are calculated. The results show that the Yb3+-doped new gallium--lead--germanate glass has good thermal stability (ΔT=198°C), high stimulated emission cross section (0.79pm2), and long fluorescence lifetime (1.46ms). Compared with other Yb3+-doped glass hosts, the Yb3+-doped new gallium--lead--germanate glass has better laser performance parameters and laser properties, indicating that Yb3+-doped new gallium--lead--germanate glass is a promising laser material for short pulse generation in diode pumped lasers, short pulse generation tunable laser, high-peak power and high-average power lasers.
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Red Electrophosphorescence from Oxadiazoles-Functionalized Iridium Complexes in Polymer Light-Emitting Devices
WU Zhong-Lian, LUO Cui-Ping, HU Zheng-Yong, JIANG Chang-Yun, HUANG Feng-Liang, ZHU Ke-Ming, ZHU Mei-Xiang,
ZHU Wei-Guo
Chin. Phys. Lett. 2006, 23 (11):
3091-3093
.
A type of oxadiazole-functionalized iridium complex is newly employed as red phosphor emitter in polymer light-emitting devices (PLEDs) using a blend of poly (9,9-dioctylfluorene)(PFO) and 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole (PBD) as a host matrix. The devices show bright red electrophosphorescence with dominant peaks at about 593nm and shoulders at about 642nm. The highest luminance efficiency of 3.3cd/A at 9.3V and maximum luminance of 2912cd/m2 at 14.0V are achieved in the devices. At current density of 100mA/cm2, the devices still exhibit luminance efficiency of 2.2cd/A and luminance of 2300cd/m2. This indicates that the oxadiazole-functionalized iridium complexes have improved optoelectronic properties in the devices at high current density.
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Improved Performances for Organic Light-Emitting Diodes Based on Al2O3-Treated Indium--Tin Oxide Anode
WANG Jing, SONG Rui-Li, LIU Chun-Ling, JIANG Wen-Long, CHEN Shu-Fen, ZHAO Yi, HOU Jing-Ying, LIU Shi-Yong
Chin. Phys. Lett. 2006, 23 (11):
3094-3096
.
Improved performances are obtained in organic light-emitting diodes (OLEDs) based on the indium--tin oxide (ITO) anode processed with ultrasonic in AlAl2O3 polishing solution. By optimizing the AlAl2O3 granularity to 0.6μm and the ultrasonic time to 10min, smoother ITO surfaces are acquired, which lead to the enhanced hole injection, and furthermore, to improving the performance of OLEDs. Compared with the control device without any treatment, the drive voltage of treatment device falls from 9V to 6V at 100cd/m2, the luminance is over three times that of the control device, reaching 25880cd/m2 at 15V, and the luminous efficiency is 3.82cd/A.
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Two-Photon Absorption Properties of Mn-Doped ZnS Quantum Dots
ZHENG Jia-Jin, ZHANG Gui-Lan, GUO Yang-Xue, WANG Xiao-Yan, CHEN Wen-Ju, ZHANG Xiao-Song, HUA Yu-Lin
Chin. Phys. Lett. 2006, 23 (11):
3097-3100
.
We investigate the two-photon absorption and nonlinear refractive index properties of a quantum dot material based on ZnS nanocrystals doped with Mn isoelectronic impurities, using the Z-scan technique with 532\,nm picosecond laser pulses. The Mn-doped ZnS quantum dots have an average two-photon absorption cross section as high as 13600 Goeppert--Mayer units, which turn it into a very promising material for fluorescent label and imaging in biological samples. In addition, we also found that the two-photon absorption coefficient initially increases and then decreases with increasing pulse irradiance, which demonstrates the presence of the higher-order nonlinearity under the strong excitation.
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Memory-Based Boolean Game and Self-Organized Phenomena on Networks
HUANG Zi-Gang, WU Zhi-Xi, GUAN Jian-Yue, WANG Ying-Hai
Chin. Phys. Lett. 2006, 23 (11):
3119-3122
.
We study a memory-based Boolean game (MBBG) taking place on a regular ring, wherein each agent acts according to its local optimal states of the last M time steps recorded in memory, and the agents in the minority are rewarded. One free parameter p between 0 and 1 is introduced to denote the strength of the agent willing to make a decision according to its memory. It is found that giving proper willing strength p, the MBBG system can spontaneously evolve to a state of performance better than the random game; while for larger p, the herd behaviour emerges to reduce the system profit. By analysing the dependence of dynamics of the system on the memor capacity M, we find that a higher memory capacity favours the emergence of the better performance state, and effectively restrains the herd behaviour, thus increases the system profit. Considering the high cost of long-time memory, the enhancement of memory capacity for restraining the herd behaviour is also discussed, and M=5 is suggested to be a good choice.
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66 articles
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