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Volume 27 Issue 10
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Evolutionary Prisoners' Dilemma Game on Scale-Free Networks with Degree-Degree Correlation
CHENG Hong-Yan, DAI Qiong-Lin, LI Hai-Hong, YANG Jun-Zhong
Chin. Phys. Lett. 2010, 27 (10): 100201 .   DOI: 10.1088/0256-307X/27/10/100201
Abstract   PDF(pc) (565KB) ( 543 )
Degree-degree correlation and heterogeneity in degree are important topological properties characterizing scale-free networks. We consider an evolutionary prisoners' dilemma game on scale-free networks and investigate how degree-degree correlation influences cooperation. It is found that the cooperator frequency displays resonance-like behavior with the variation of Pearson correlation coefficient. A measure on local heterogeneity in a network is proposed and it is realized that cooperation is proportional to the local heterogeneity.
Entanglement Dynamics of Three Qubits in the Non-Markovian Environments
SHAN Chuan-Jia, LIU Ji-Bing, CHEN Tao, LIU Tang-Kun, HUANG Yan-Xia, LI Hong
Chin. Phys. Lett. 2010, 27 (10): 100301 .   DOI: 10.1088/0256-307X/27/10/100301
Abstract   PDF(pc) (626KB) ( 612 )
We consider the entanglement dynamics of three two-level atoms interacting with independent structured non-Markovian reservoirs. The atoms are initially prepared in a mixed multipartite Greenberger-Horne-Zeilinger (GHZ)-type state. Based on the purity and non-Markovian reservoirs, we show that the reservoirs' entanglement can exhibit not only multipartite entanglement sudden birth but also entanglement sudden death, and the revival of atom entanglement is not always accompanied by the disentanglement of reservoirs. Meanwhile, we derive the quantitative criteria for multipartite revival and death phenomena and find multipartite entanglement sudden death and entanglement sudden birth simultaneous apparition time is independent of the initial three-qubit state.
Single-Qubit Operations for Singlet-Triplet Qubits in an Isolated Double-Well with Fixed Tunneling
QIAN Jun, QIAN Yong, KE Min, YAN Bo, CHENG Feng, ZHOU Shu-Yu, WANG Yu-Zhu
Chin. Phys. Lett. 2010, 27 (10): 100302 .   DOI: 10.1088/0256-307X/27/10/100302
Abstract   PDF(pc) (492KB) ( 439 )
We propose a scheme to implement single-qubit operations for singlet-triplet qubits located in an isolated double-well potential with fixed inter-site tunneling when superexchange interactions predominate. Arbitrary single-qubit gates can be realized by a sequence composed of two elementary operations which can be switched between different parameter regimes by adjusting slightly the relative energy bias of trapped atoms in each sub-well site. The experimental feasibility of the strategy and the fidelity of basic rotation operations are also analyzed.
One-to-Many Economical Phase-Covariant Cloning and Telecloning of Qudits
WANG Xin-Wen, SU Yu-Huan, YANG Guo-Jian
Chin. Phys. Lett. 2010, 27 (10): 100303 .   DOI: 10.1088/0256-307X/27/10/100303
Abstract   PDF(pc) (418KB) ( 503 )
We present explicit unitary transformations for realizing both symmetric and asymmetric one-to-many economical phase-covariant clonings of qudits. We also propose a corresponding telecloning scheme. It is shown that the fidelity of the telecloning with nonmaximally entangled states can be larger than that of the corresponding cloning. This implies that partially entangled states can be better than the maximally entangled states for our economical phase-covariant telecloning scheme.
Efficient Polarization Entanglement Purification Using Spatial Entanglement
GU Bin, CHEN Yu-Lin, ZHANG Cheng-Yi, HUANG Yu-Gai
Chin. Phys. Lett. 2010, 27 (10): 100304 .   DOI: 10.1088/0256-307X/27/10/100304
Abstract   PDF(pc) (423KB) ( 437 )
The protocol using spatial entanglement to purify polarization entanglement by entanglement transformation between different degrees of freedom in a realistic environment is elaborated. Our analyses show that the bit-flip error can be completely purified, but the pure maximally entangled state can not be obtained ultimately if the spatial entanglement is impure. The fidelity of the purified state is decided by the spatial entanglement. Furthermore, this protocol can also be extended to purify the multi-particle Greenberg-Horne-Zeilinger (GHZ) state. It is presented that the spatial entanglement can be served as another source to improve the quality of entanglement.
Multi-Atom Entanglement Engineering in Distant Cavities via Resonant Interaction
ZHONG Zhi-Rong
Chin. Phys. Lett. 2010, 27 (10): 100305 .   DOI: 10.1088/0256-307X/27/10/100305
Abstract   PDF(pc) (388KB) ( 416 )
We propose a scheme for the generation of entangled states for multiple atoms trapped in three distant cavities connected by two identical single-mode fibers. Compared with the previous schemes, the distinct advantages of the proposed scheme are: First, all the cavities in the proposed protocol can interact with each other freely, which is important in quantum communication and distributed quantum computation. Secondly, in the scheme, the atoms, cavities, and fiber mode are in resonance. Thus, the required interaction time is short, which is important in view of decoherence. In principle, the proposed scheme can be extended to generate n atoms entangled states.
A New Model For the Double Well Potential
TIAN Gui-Hua, ZHONG Shu-Quan
Chin. Phys. Lett. 2010, 27 (10): 100306 .   DOI: 10.1088/0256-307X/27/10/100306
Abstract   PDF(pc) (389KB) ( 631 )
A new model for the double well potential is presented. In the new potential, the exchanging rate could be easily calculated by the perturbation method in supersymmetric quantum mechanics. It gives good results whether the barrier is high or sallow. The new model has many merits and may be used in the double well problem.
Cylindrically Symmetric Solution in Teleparallel Theory
Gamal G. L. Nashed,
Chin. Phys. Lett. 2010, 27 (10): 100401 .   DOI: 10.1088/0256-307X/27/10/100401
Abstract   PDF(pc) (453KB) ( 377 )
The field equations of a special class of teleparallel theory of gravitation and electromagnetic fields are applied to tetrad space having cylindrical symmetry with four unknown functions of radial coordinate r and azimuth angle θ. The vacuum stress−energy momentum tensor with one assumption concerning its specific form generates one non-trivial exact analytic solution. This solution is characterized by a constant magnetic field parameter B0. If B0=0, then the solution will reduce to the flat spacetime. The energy content is calculated using the superpotential given by Møller in the framework of teleparallel geometry. The energy contained in a sphere is found to be different from the pervious results
Adaptive Consensus Problem of Leader-Follower Multi-Agent System
ZHANG Qing, CHEN Shi-Hua, GUO Wan-Li
Chin. Phys. Lett. 2010, 27 (10): 100501 .   DOI: 10.1088/0256-307X/27/10/100501
Abstract   PDF(pc) (494KB) ( 569 )
We consider the adaptive consensus problem for leader-follower multi-agent systems with time delay coupling. Under the condition that the interconnection graph of the agents is directed and balanced, a neighbor-based consensus protocol with adaptive feedback gain is proposed for the follower agents to track the leader. The stability is performed based on the Lyapunov stability theorem. Some simulation examples are provided to show the efficiency of the control scheme.
A Demonstration of Equivalence between Parameter-Induced and Noise-Induced Stochastic Resonances with Multiplicative and Additive Noises
LI Jian-Long, ZENG Ling-Zao, ZHANG Hui-Quan
Chin. Phys. Lett. 2010, 27 (10): 100502 .   DOI: 10.1088/0256-307X/27/10/100502
Abstract   PDF(pc) (425KB) ( 587 )
A typical bistable nonlinear system with multiplicative and additive noises can produce stochastic resonance (SR) by increasing the intensity of the additive noise or the multiplicative noise and it has been proved that SR can also be realized by tuning system parameters. We clearly demonstrate the equivalence between parameter-induced SR (PSR) and noise-induced SR in the presence of multiplicative and additive noises. By tuning several system parameters with fixed noise intensities, the SR is induced just as it is realized by tuning the additive noise or the multiplicative noise. It may be interesting to realize PSR when the noise intensity exceeds the resonance level, or when the characteristic of the noise is unknown.
Two Optical Feedback Schemes for Cavity Ring-down Technique for High Reflectivity Measurements
ZHAO Tong-Kai, QU Zhe-Chao, HAN Yan-Ling, LI Bin-Cheng
Chin. Phys. Lett. 2010, 27 (10): 100701 .   DOI: 10.1088/0256-307X/27/10/100701
Abstract   PDF(pc) (586KB) ( 548 )
An optical feedback cavity ring-down (OF-CRD) technique employing a continuous wave Fabry-Perot (F-P) diode laser is investigated for high reflectivity measurement. Two optical feedback (OF) schemes (linear and V-shaped cavity schemes) for the OF-CRD technique are compared in both wavelength and time domains. Due to the OF effect caused by retro-reflection of ring-down cavity back into the laser cavity, large resonance peaks appear in CRD signals in both the schemes. However, due to the differences in the strengths and spectra of the OF, the appearance frequencies and amplitudes of the peaks in the CRD signals in both schemes differ significantly. Simple and low-cost high reflectivity measurement apparatuses are established based on these two OF-CRD schemes and high-accuracy measurements of high reflectivity are experimentally achieved.
Supercontinuum Generation with Output Power of 1.7W Pumped by a Picosecond Laser Pulse
PAN Er-Ming, RUAN Shuang-Chen, GUO Chun-Yu, WANG Yun-Cai, WEI Hui-Feng
Chin. Phys. Lett. 2010, 27 (10): 100702 .   DOI: 10.1088/0256-307X/27/10/100702
Abstract   PDF(pc) (540KB) ( 575 )
By using a photonic crystal fiber, a supercontinuum source with output power up to 1.7 W, pumped by a passively mode-locked diode-pumped Nd:YVO4 picosecond laser is obtained. A spectral width of the supercontinuum is 1700 nm (500-2200 nm) with the 5 dB spectral width approximately 1000 nm (1200-2200 nm). This high power wide band supercontinuum source meets the demand of many applications such as optical coherence tomography, frequency metrology and wavelength-division-multiplexing systems. The evolution of the supercontinuum with the increasing pump power is presented and analyzed.
Analysis of the X(1835) as a Baryonium State with the Bethe-Salpeter Equation
WANG Zhi-Gang
Chin. Phys. Lett. 2010, 27 (10): 101201 .   DOI: 10.1088/0256-307X/27/10/101201
Abstract   PDF(pc) (446KB) ( 353 )
We take the X(1835) as a pseudoscalar baryonium state, and calculate the mass spectrum of the baryon−antibaryon bound states pp, ΣΣ, ΞΞ, and ΛΛ in the framework of the Bethe−Salpeter equation with a phenomenological potential. The numerical results indicate the pp, ΣΣ and ΞΞ bound states may exist, and the X(1835) can be tentatively identified as the pp bound state.
Intermediate Mass Dileptons from the Passage of Jets and High Energy Photons through Quark-Gluon Plasma
FU Yong-Ping, LI Yun-De
Chin. Phys. Lett. 2010, 27 (10): 101202 .   DOI: 10.1088/0256-307X/27/10/101202
Abstract   PDF(pc) (555KB) ( 450 )
The production of the intermediate mass dileptons originating from the annihilation and Compton scattering of the jets and high energy photons (resolved photons) passing through the quark-gluon plasma is calculated. The contribution of the dilepton yield due to the jet-plasma and high energy photon-plasma interaction is pronounced compared to the thermal and Drell-Yan dilepton spectrum at intermediate mass. The ordinary spectrum of thermal and Drell-Yan processes is enhanced by the jet and photon-plasma mechanism. The numerical results match to the PHENIX data accurately in the intermediate mass region for Au-Au 200 GeV/A collisions at RHIC.
Production of Charged Higgs Boson Associated with Top Partner at the Large Hadron Collider
YUE Chong-Xing, SU Xue-Song, MA Wei, ZHANG Ting-Ting
Chin. Phys. Lett. 2010, 27 (10): 101203 .   DOI: 10.1088/0256-307X/27/10/101203
Abstract   PDF(pc) (658KB) ( 375 )
In the context of the littlest Higgs (LH) model and the left-right twin Higgs (LRTH) model, we study the production of charged Higgs boson associated with top partner at the LHC. We find that, in the LH model, its cross section can be significantly larger for the scale parameter f = 500 GeV, while sharply decreases as f increases. In the LRTH model, this production process mainly transfers to the tbbb final state at the Large Hadron Collider and its production rate can reach 167.2 fb.
Effect of the Tensor Force on Charge-Exchange Spin-Dependent Multipole Excitations
BAI Chun-Lin, **, ZHANG HUAN-Qiao, ZHANG Xi-Zhen, XU Fu-Rong, H. Sagawa, G. Colò,
Chin. Phys. Lett. 2010, 27 (10): 102101 .   DOI: 10.1088/0256-307X/27/10/102101
Abstract   PDF(pc) (809KB) ( 439 )
The charge-exchange spin-dipole (SD) and spin-quadrupole (SQ) strength functions of 90Zr are calculated with and without the tensor terms of the Skyrme interaction in self−consistent HF+RPA approach. It is found that, in SD and SQ transitions, the RPA correlations associated with the tensor terms shift dramatically the strengths of (Ylσ)λ=l-1 and (Ylσ)λ=l modes upward and downward, respectively, and also shift the strengths of (Ylσ)λ=l+1 modes upward. The coupling between (Yl=λ−1σ)λ and (Yl=λ+1σ)λ modes arising from the tensor correlation is noticeable. The RPA tensor correlations produce strengths of SD and SQ modes, which are distributed in a much wider energy range, and the (Ylσ)λ=l−1 modes dominate the high energy part of the strength functions. These energy shifts and coupling effects of different modes can be understood qualitatively by expressing a finite range tensor force in a separable form.
Exploring Scaling Laws of Valence Neutron Distributions for Medium Nuclei
GUO Yan-Qing, REN Zhong-Zhou,
Chin. Phys. Lett. 2010, 27 (10): 102102 .   DOI: 10.1088/0256-307X/27/10/102102
Abstract   PDF(pc) (578KB) ( 434 )
The root-mean-square radii of the valence neutron distributions for many nuclei in He-Mo mass range are calculated in the framework of the single-particle potential model. The scaling laws of valence neutron distributions are obtained by analyzing the relations between the radii and the binding energies of the valence neutrons. Based on these scaling laws, the necessary conditions for the occurrence of neuron halos in 2s1/2, 1p3/2, 1p1/2, 2p3/2, 2p1/2, 1d5/2 and 1d3/2 states are deduced, respectively. The derived quantitative conditions for halo occurrence can provide reference for the searching of neutron halos up to medium nuclei.
Search for Ring-Like Nuclei under Extreme Conditions
ZHANG Wei, LIANG Hao-Zhao, ZHANG Shuang-Quan, MENG Jie,
Chin. Phys. Lett. 2010, 27 (10): 102103 .   DOI: 10.1088/0256-307X/27/10/102103
Abstract   PDF(pc) (560KB) ( 369 )
The potential energy surfaces of 24Mg are studied within the adiabatic and diabatic constrained relativistic mean field approaches. The possible ring−like states are searched by analyzing the density distribution. It is found that in 24Mg the ring−like states are energetically favored at the extreme oblate condition 2| ≥1.54 and a ring−like minimum is obtained with excitation energy Ex=49.42 MeV and quadrupole deformation β2=−0.93.
Shell Structures in 91Nb
HE Chuang-Ye, CUI Xing-Zhu, ZHU Li-Hua, WU Xiao-Guang, LI Guang-Sheng, LIU Ying, WANG Zhi-Min, WEN Shu-Xian, SUN Hui-Bin, MA Rui-Gang, YANG Chun-Xiang
Chin. Phys. Lett. 2010, 27 (10): 102104 .   DOI: 10.1088/0256-307X/27/10/102104
Abstract   PDF(pc) (552KB) ( 491 )
High spin states of 91Nb are populated via the fusion−evaporation reaction 76Ge (19F, 4n)91Nb at the beam energy of 80 MeV. The existing level scheme is modified and extended to higher spins. Its low−lying states are well described by the weakly coupling between a g9/2 proton and the even−even 90Zr core, whereas the higher level structures could be interpreted by the multi−particle excitations in the model space p (1f5/2,2p1/2,1g9/2) n (1g9/2,2d5/2,1g7/2) in the framework of the shell model.
Quasi-Classical Trajectory Study on Ar+H2+/D2+/T2+ Reactions
LIU Hui-Rong, LIU Xin-Guo, SUN Hai-Zhu, ZHANG Qing-Gang
Chin. Phys. Lett. 2010, 27 (10): 103101 .   DOI: 10.1088/0256-307X/27/10/103101
Abstract   PDF(pc) (857KB) ( 391 )
In order to explore the isotope effect on stereodynamics, we investigate the trajectory calculations of Ar+H2+, Ar+D2+ and Ar+T2+ reactions on the ab initio potential energy surface constructed by us and calculate the distributions of product polarization P(θr), P(φr) and four generalized polarization−dependent differential cross-sections. The product rotational alignment parameters <2(j'⋅k)> for the title reactions are compared and discussed with mass factors. Furthermore, the angular distributions of the product rotational vectors in the form of polar plot in θr and φr are presented. The results indicate that the stereodynamics properties of the title reactions are sensitive to the mass factor.
Vibrational Spectra of Distorted Structure Molecules by Using Lie Algebraic Techniques: an Application to Copper and Magnesium Octaethyl Porphyrin
Srinivasa Rao Karumuri
Chin. Phys. Lett. 2010, 27 (10): 103301 .   DOI: 10.1088/0256-307X/27/10/103301
Abstract   PDF(pc) (394KB) ( 431 )
Using a U(2) algebraic model the fundamental stretching vibrations of copper octaethyl porphyrin and magnesium octaethyl porphyrin are calculated for 24 vibrational bands. The locality parameter ξ confirms the highly local behavior of the stretching modes of these porphyrin molecules. The model Hamiltonian so constructed appears to describe the vibrational energy levels accurately.
Positron-Impact Ionization of Atomic Hydrogen in a Bichromatic Laser Field in the Second Born Approximation
LOU Jun, LI Shu-Min,
Chin. Phys. Lett. 2010, 27 (10): 103401 .   DOI: 10.1088/0256-307X/27/10/103401
Abstract   PDF(pc) (645KB) ( 447 )
The positron impact-ionization of atomic hydrogen in the presence of a linearly polarized bichromatic field is investigated in the second Born approximation. The field is composed of a fundamental frequency and its second harmonic. The state of positron in the field is described by the Volkov wavefunction, and the continuum state of the ejected electron is described by the Coulomb-Volkov wavefunction. The dressed ground state of target is a first order time-dependent perturbative wavefunction. The triple differential cross sections and their dependencies on laser field parameters are discussed. Numerical results demonstrate that the second-order effect plays a crucial role in understanding the laser-assisted positron scattering process.
Doppler Shifts of Backscattering Fields from One Dimensional Linear and Nonlinear Oceanic Surface by SSA-II
WANG Yun-Hua, ZHANG Yan-Min, GUO Li-Xin
Chin. Phys. Lett. 2010, 27 (10): 104101 .   DOI: 10.1088/0256-307X/27/10/104101
Abstract   PDF(pc) (595KB) ( 639 )
Based on the general framework of the second order small slope approximation (SSA-II), Doppler shifts of backscattered fields from linear and nonlinear hydrodynamic sea surfaces are predicted. Comparisons are performed at incidence angles varying from near-nadir to moderate-grazing for different radar frequencies. The predicted Doppler shifts for nonlinear hydrodynamic model are somewhat larger than the results corresponding to linear surface. Meanwhile, the dependences of the Doppler shifts on the wind speed and radar polarizations are also analyzed, and the comparisons are shown to confirm the sensitivities to the polarization and wind speed. At the same time, the results of the small perturbation method (SPM) and geometrical optics approximation (GO) are also presented for comparisons.
Mueller-Matrix-Based Differential Rotation Method for Precise Measurement of Fiber Birefringence Vector
LI Zheng-Yong, WU Chong-Qing, SHANG Chao, YU Xiang-Zhi
Chin. Phys. Lett. 2010, 27 (10): 104201 .   DOI: 10.1088/0256-307X/27/10/104201
Abstract   PDF(pc) (455KB) ( 698 )
The method of complete polar decomposition for arbitrary Mueller matrixes is introduced to analyze the birefringence vector induced in a fiber, and then based on the Mueller matrix (MM) method, three kinds of computation methods including the absolute, the relative, and the differential rotation methods are proposed and investigated in detail. A computer-controlled measure system is employed to measure the Mueller matrix and birefringence vector for a 2.5-km fiber system with length 5 mm under lateral press in complicated environment with much perturbation. Experimental results show that the differential rotation (DR) method is the optimal approach to achieve fiber birefringence vectors in a large dynamic range of lateral press on fibers in perturbed situations, which reaches the highest linearity of 0.9998 and average deviation below 2.5%. Further analyses demonstrate that the DR method is also available for accurate orientation of lateral press direction and the average deviation is about 1.1°.
Observation of Autler-Townes Effect in Electromagnetically Induced Transparency
DU Zhi-Jing, ZHANG Shou-Gang, WU Chang-Jiang, GUAN Yong, ZHAO Wen-Yu, CHANG Hong
Chin. Phys. Lett. 2010, 27 (10): 104202 .   DOI: 10.1088/0256-307X/27/10/104202
Abstract   PDF(pc) (610KB) ( 612 )
We report an experimental observation of Autler-Townes doublet splitting in electromagnetically induced transparency (EIT) resonance. The splitting is introduced by a coherent microwave field, which perturbs a three-level Λ-type EIT system through an auxiliary level. The doublet splitting of EIT resonance is demonstrated in two cases, where the microwave field shares a common lower level with coupled or probe transition, respectively. The dependence of doublet splitting on microwave field intensity and detuning is measured. This may provide a feasible way of manipulating the atomic states with both laser and microwave field.
On-Chip All-Optical Passive 3.55Gbit/s NRZ-to-PRZ Format Conversion Using a High-Q Silicon-Based Microring Resonator
ZHAI Yao, CHEN Shao-Wu, REN Guang-Hui
Chin. Phys. Lett. 2010, 27 (10): 104203 .   DOI: 10.1088/0256-307X/27/10/104203
Abstract   PDF(pc) (574KB) ( 431 )
We report the experimental result of all-optical passive 3.55 Gbit/s non-return-to-zero (NRZ) to pseudo-return-to-zero (PRZ) format conversion using a high-quality-factor (Q-factor) silicon-based microring resonator notch filter on chip. The silicon-based microring resonator has 23800 Q-factor and 22 dB extinction ratio (ER), and the PRZ signals has about 108 ps width and 4.98 dB ER.
Harmonic Millimeter Wave Generation and Frequency Up-Conversion Using Optical Injection Locking and Brillouin Selective Sideband Amplification
LI Wei, ZHU Ning-Hua, WANG Li-Xian, LIU Jian-Guo, QI Xiao-Qiong, XIE Liang
Chin. Phys. Lett. 2010, 27 (10): 104204 .   DOI: 10.1088/0256-307X/27/10/104204
Abstract   PDF(pc) (584KB) ( 553 )
Harmonic millimeter wave (mm-wave) generation and frequency up-conversion are experimentally demonstrated using optical injection locking and Brillouin selective sideband amplification (BSSA) induced by stimulated Brillouin scattering in a 10-km single-mode fiber. By using this method, we successfully generate third-harmonic mm-wave at 27 GHz (f LO=9 GHz) with single sideband (SSB) modulation and up-convert the 2 GHz intermediate frequency signal into the mm-wave band with single mode modulation of the SSB modes. In addition, the mm-wave carrier obtains more than 23 dB power gain due to the BSSA. The transmission experiments show that the generated mm-wave and up-converted signals indicate strong immunity against the chromatic dispersion of the fibers.
Terahertz Quantum Cascade Laser Operating at 2.94THz
LIU Jun-Qi, CHEN Jian-Yan, LIU Feng-Qi, LI Lu, WANG Li-Jun, WANG Zhan-Guo
Chin. Phys. Lett. 2010, 27 (10): 104205 .   DOI: 10.1088/0256-307X/27/10/104205
Abstract   PDF(pc) (792KB) ( 580 )
The development of quantum cascade laser at 2.94 THz is reported. The laser structure is based on a bound-to-continuum active region and a semi-insulating surface-plasmon waveguide. Lasing is observed up to a heat-sink temperature of 70 K in pulsed mode with light power of 4.75 mW at 10 K and 1 mW at 70 K. A threshold current density of 296.5 A/cm2 and an internal quantum efficiency of 1.57×10−2 per cascade period are also observed at 10 K. The characteristic temperature of this laser is extracted to be T0= 57.5 K.
Glass/Ta2O5 Composite Waveguides for Application as an Integrated Polarimetric Interferometer
LU Dan-Feng, QI Zhi-Mei
Chin. Phys. Lett. 2010, 27 (10): 104206 .   DOI: 10.1088/0256-307X/27/10/104206
Abstract   PDF(pc) (552KB) ( 480 )
A tapered thin film of Ta2O5 was deposited by the masked sputtering method on a single−mode slab glass waveguide to form a composite optical waveguide (COWG) with a great modal birefringence. With the prism-coupling method the COWG was used as an integrated polarimetric interferometer for real-time detection of chemical and biological measurands. The refractive-index sensitivity of the interferometer was examined, and the refractive-index increments of different aqueous solutions were determined with the device. Response of the interferometer to protein adsorption and that to water temperature were investigated. The experimental results indicate that an increase of ΔT=1°C for the temperature of water in the measuring chamber can lead to a phase−difference change of Δφ= -28.5°.
150-W Tm3+-Doped Fiber Lasers With Different Cooling Techniques and Output Couplings
TANG Yu-Long, XU Jian-Qiu, CHEN Wei, LI Shi-Yu
Chin. Phys. Lett. 2010, 27 (10): 104207 .   DOI: 10.1088/0256-307X/27/10/104207
Abstract   PDF(pc) (487KB) ( 604 )
A home-made double-clad Tm3+−doped silica fiber laser with over 150-W output power is reported. Pumped with a diode bar at 793 nm, the fiber laser is operated at 2.04 μm with a slope efficiency of 56.3%. A quantum efficiency of >140% is achieved owing to the efficient cross−relaxation process in heavily Tm3+-doped fibers. By using different fiber-cooling techniques, the slope efficiency shows a deviation over 10%. The influence of output coupling on the laser characteristics is also investigated.
Capping-Barrier Layer Effect on Quantum Dot Optoelectronic Characteristics
A. Rostami, **, H. Rasooli Saghai, H. Baghban, N. Sadoogi, Y. Seyfinejad
Chin. Phys. Lett. 2010, 27 (10): 104208 .   DOI: 10.1088/0256-307X/27/10/104208
Abstract   PDF(pc) (633KB) ( 450 )
We present a study of capping-barrier layer (CBL) effect on electro-optical properties of box- and spherical-shaped quantum dots as well as of the electronic transport of a QDs-array. It is shown that increasing the CBL-width leads to a considerable enhancement in third-order optical nonlinear susceptibilities (14 times in the quadratic electro-optic effect, 31 times for ω=ω0/3 and 14 times for ω=ω0 in the third harmonic generation). The capping-barrier layer thus can be employed as a degree of freedom in engineering the electro-optical specifications of quantum-dot-based devices.
Improvement of Quality of Reconstructed Images in Multi-Frame Fresnel Digital Holography
LU Xiao-Wei, LI Jing-Zhen, CHEN Hong-Yi
Chin. Phys. Lett. 2010, 27 (10): 104209 .   DOI: 10.1088/0256-307X/27/10/104209
Abstract   PDF(pc) (515KB) ( 444 )
A modified reconstruction algorithm to improve the quality of reconstructed images of multi-frame Fresnel digital holography is presented. When the reference beams are plane or spherical waves with azimuth encoding, by introducing two spherical wave factors, images can be reconstructed with only one time Fourier transform. In numerical simulation, this algorithm could simplify the reconstruction process and improve the signal-to-noise ratio of the reconstructed images. In single-frame reconstruction experiments, the accurate reconstructed image is obtained with this simplified algorithm.
Double Wire-Grid Terahertz Polarizer on Low-Loss Polymer Substrates
TIAN Dong-Bin, ZHANG Huai-Wu, LAI Wei-En, WEN Qi-Ye, SONG Yuan-Qiang, WANG Zhi-Guo
Chin. Phys. Lett. 2010, 27 (10): 104210 .   DOI: 10.1088/0256-307X/27/10/104210
Abstract   PDF(pc) (802KB) ( 669 )
A double-wire-grid polarizer was fabricated on both sides of a low-loss polythene film by simple electroplating and photolithographic micro-processing techniques. The performances of the polarizer were measured using a terahertz time-domain spectrometer (THz-TDS). The transmittance is more than 70% and below 2% in the parallel and perpendicular directions of the polarizer, respectively. The extinction ratio is better than 22 dB in the broad frequency range of 0.5-3 THz, which is higher than the conventional free-standing polarizer in the high frequency region.
FM-AM Conversion Induced by Polarization Mode Dispersion in Fiber Systems
HUANG Xiao-Dong, WANG Jian-Jun, LI Ming-Zhong, XU Dang-Peng, LIN Hong-Huan, ZHANG Rui, DENG Ying, ZHANG Xiao-Min, ZHAO Sheng-Zhi
Chin. Phys. Lett. 2010, 27 (10): 104211 .   DOI: 10.1088/0256-307X/27/10/104211
Abstract   PDF(pc) (594KB) ( 409 )
The conversion of the frequency modulated pulse induced from frequency modulation (FM) to amplitude modulation (AM) by the polarization mode dispersion (PMD) is theoretically and experimentally investigated. When there is no polarizer at the output end of a fiber system, the amplitude modulation depth is stable by 8%. Random amplitude modulation is observed when a polarizer is placed at the output end of the fiber system. The observed minimum and maximum modulation depths in our experiment are 5% and 80%, respectively. Simulation results show that the amplitude modulation is stable by 4% induced mainly by group velocity dispersion (GVD) when there is no polarizer, and the amplitude modulation depth displays the random variation character induced by the GVD and PMD. Lastly, a new fiber system scheme is proposed and little amplitude modulation is observed at the top of the output pulse.
Laser Diode Pumped 1342nm Nd:YVO4 Slab Laser with a Compact Hybrid Resonator
ZHANG Heng-Li, XU Liu, CUI Li, YAN Ying, LI Jing, SHA Peng-Fei, XIN Jian-Guo
Chin. Phys. Lett. 2010, 27 (10): 104212 .   DOI: 10.1088/0256-307X/27/10/104212
Abstract   PDF(pc) (414KB) ( 475 )
An 880-nm laser-diode stack end-pumped cw 1342 nm Nd:YVO4 slab laser with a compact positive confocal unstable−stable hybrid resonator is demonstrated. At absorbed pump power of 115 W, the output power 32.4 W is obtained. The slope efficiency and optical-to-optical conversion efficiency are 42% and 28.2%, respectively. At output power of 22 W, the stable direction M2 is 1.3 and the unstable direction M2 is 1.2.
Exact Calculation of Local Density of States in Two-Dimensional Photonic Crystals
HUANG Yong-Gang, FAN Heng, WANG Xue-Hua
Chin. Phys. Lett. 2010, 27 (10): 104213 .   DOI: 10.1088/0256-307X/27/10/104213
Abstract   PDF(pc) (857KB) ( 642 )
An exact calculation method of local density of states (LDOS) in two-dimensional (2D) photonic crystals (PCs) is presented. In order to calculate the LDOS, the eigen-equation of magnetic field is first solved by the plane-wave expansion method, then the eigen-modes of electric-field are obtained. There are two different ways to solve the eigen-equantion of magnetic field and three different ways to obtain the eigen-modes of the electric-field. In comparison of the numerical results from these different ways, an exact and fast method for calculating the LDOS in PCs is found. With use of this method, we investigate the LDOS of the 2D PCs consisting of a triangular lattice of cylinders. The results show the large LDOS is favorable to reside in higher dielectric-constant medium in high frequency region, rather than in lower dielectric-constant medium.
Focusing of Time Reversal Lamb Waves and Its Applications in Structural Health Monitoring
ZHANG Hai-Yan, CHEN Xian-Hua, CAO Ya-Ping, YU Jian-Bo
Chin. Phys. Lett. 2010, 27 (10): 104301 .   DOI: 10.1088/0256-307X/27/10/104301
Abstract   PDF(pc) (735KB) ( 470 )
The focusing of time reversal acoustic fields for dispersive and multimodal Lamb waves is theoretically investigated and experimentally verified. It is demonstrated that the time reversal Lamb wave signal will reach the maximum amplitude when the observation point is located at the damage location. Based on the time reversal focusing theory, a damage imaging method is proposed for structural health monitoring using Lamb waves. The experiments employ a transducer network consisting of four piezoelectric transducers as actuators and as well sensors for excitation and measurement of Lamb waves. The results show that this method is able to accurately predict damage location and provides an estimation of the possible area even for damage close to one of the transducers or even slightly outside the transducer network.
Characteristics of Flow around an Impulsively Rotating Square Cylinder via LB-DF/FD Method
NIE De-Ming, LIN Jian-Zhong,
Chin. Phys. Lett. 2010, 27 (10): 104701 .   DOI: 10.1088/0256-307X/27/10/104701
Abstract   PDF(pc) (1107KB) ( 530 )
Flow around an impulsively rotating square cylinder in a viscous fluid in range of 1≤Re≤300 is numerically investigated by the previously developed LB−DF/FD method, which combines the lattilce Boltzmann method (LBM) and direct-forcing fictitious domain (DF/FD) scheme. Results show that in total three kinds of transient characteristics depending on Re are observed: 1≤Re< 20, four vortices arising from the corners of the square cylinder separate from the surfaces and gradually become stable without vortex integration or shedding; 20≤Re< 100, vortices integration is observed when they grow long enough, then separated from each other; Re≥100, vortex shedding takes place in this regime. The shedding vortex joins the downstream vortex to form a new one. It is also found that vortex shedding happens more than one time when Re≥160. Furthermore, each vortex shedding induces a fluctuation in the torque exerted on the cylinder.
Singular Wave Solutions of Two Integrable Generalized KdV Equations
ZHANG Zheng-Di, BI Qin-Sheng
Chin. Phys. Lett. 2010, 27 (10): 104702 .   DOI: 10.1088/0256-307X/27/10/104702
Abstract   PDF(pc) (935KB) ( 383 )
We present some singular wave solutions such as multi-peaked periodic waves, multi-peaked kink waves, multi-peaked peakons as well as kink-compactons, associated with singular curves of generalized KdV equation and modified KdV equation. When a trajectory intersects with the singular curve, it may be divided into segments. Different combinations of these segments may lead to different singular wave solutions, while at the intersection points, peaks on the waves can be observed.
Mechanism Analysis of One-Dimensional Quasiperiodic Groove Drag-Reduction
XUE Wen-Hui, GENG Xing-Guo, LI Jie, LI Feng, WU Jun
Chin. Phys. Lett. 2010, 27 (10): 104703 .   DOI: 10.1088/0256-307X/27/10/104703
Abstract   PDF(pc) (473KB) ( 408 )
Grooves arranged in one-dimensional quasiperiodic patterns are prepared by mechanical method. Drag reduction experiments are performed by R/S plus rheometer and the results show that there is a novel drag reduction effect compared with periodic grooves. An equivalent grating model is proposed to investigate the mechanism. It is found that, in comparison with periodic grating, the intensity distributes more uniform in a limited area when the coherent wave gets through quasiperiodic grating. Corresponding to the quasiperiodic grooves, the energy transfers more uniform, which could inhibit the generation of large vortices.
A Geometrical Model for Tortuosity of Tortuous Streamlines in Porous Media with Cylindrical Particles
YUN Mei-Juan, YUE Yin, YU Bo-Ming, LU Jian-Duo, ZHENG Wei
Chin. Phys. Lett. 2010, 27 (10): 104704 .   DOI: 10.1088/0256-307X/27/10/104704
Abstract   PDF(pc) (522KB) ( 1008 )
We present a three-dimensional geometry model for tortuosity of streamlines in porous media with randomly placed cylindrical particles. The proposed model is expressed as functions of porosity and geometrical parameters with no empirical constant. This might be helpful for understanding the physical mechanism for tortuosity of streamlines in three-dimensional porous media. The model predictions are found to be in good agreement with the experimental data available.
Electron Acceleration in the Bubble Regime with Dense-Plasma Wall Driven by an Ultraintense Laser Pulse
WU Hai-Cheng, XIE Bai-Song, YU Ming-Young,
Chin. Phys. Lett. 2010, 27 (10): 105201 .   DOI: 10.1088/0256-307X/27/10/105201
Abstract   PDF(pc) (946KB) ( 451 )
An optimizing scheme for electron acceleration in the wake bubble with dense-plasma wall driven by an ultraintense laser pulse is presented and investigated by particle-in-cell simulation. The wall has an inner diameter matching the expected lateral bubble size. The bubble shape can be transversely controlled and longitudinally shrunk. The accelerated electrons as a bunch have a high quality because the electrons almost stay close to the bottom of the bubble and are accelerated to much high energy with narrow energy spread.
Melting of Single-Walled Silicon Carbide Nanotubes: Density Functional Molecular Dynamics Simulation
WANG Sheng-Jie, ZHANG Chun-Lai, WANG Zhi-Guo
Chin. Phys. Lett. 2010, 27 (10): 106101 .   DOI: 10.1088/0256-307X/27/10/106101
Abstract   PDF(pc) (986KB) ( 640 )
Density functional molecular dynamics are used to study the melting behavior of single-walled SiC nanotubes. The melting of SiC nanotubes starts from the thermally activated Stone-Wales defects. The melting temperature is found to increase with the increasing diameter of nanotubes. The SiC nanotubes have a high melting temperature larger than 4000 K as the diameter larger than 1.0 nm, which indicates that the SiC nanotubes may be the best candidate of nanoscale electronic and optoelectronic devices under high temperatures.
Electrical Characteristics of Al/CNT/NiPc/PEPC/Ag Surface-Type Cell
Mutabar Shah, Kh. S. Karimov, Zubair Ahmad, M. H. Sayyad
Chin. Phys. Lett. 2010, 27 (10): 106102 .   DOI: 10.1088/0256-307X/27/10/106102
Abstract   PDF(pc) (510KB) ( 645 )
The blend of nickel phthalocyanine (NiPc) (2 wt.%) poly-N-epoxypropylcarbazole (PEPC), (1 wt.%) and carbon nano-tube (CNT) powder (2 wt.%) in benzole is deposited by drop-casting on glass substrates with pre-deposited metallic electrodes to fabricate Ag/CNT/NiPc/PEPC/Al surface type cell. It is assumed that the high nonlinearity of the I−V characteristics is related to deep traps in the nano-scale depletion region in NiPc that is observed experimentally. The values of ideality factor and barrier height are determined from the I−V curve and they are found to be 8.4 and 1.05 eV, respectively. The values of mobility and conductivity are calculated to be 7.94×10−8 cm2/Vs and 3.5×10−6 Ω-1cm−1. The values of ideality factor and series resistance are also calculated by using Cheung's functions, which are in good agreement with the values calculated from the I−V curve.
Thermal Expansion Behavior of Hexagonal ZnS Single-Crystal Nanowires Embedded in Anodized Aluminum Oxide Template
YU Yan-Long, ZHENG Li-Hui, XU Xin, SUN Hong-Yu**
Chin. Phys. Lett. 2010, 27 (10): 106201 .   DOI: 10.1088/0256-307X/27/10/106201
Abstract   PDF(pc) (805KB) ( 741 )
The thermal expansion behavior of semiconductor single-crystal nanowire arrays is of importance for their applications in electronic and optoelectronic nanodevices. We prepare hexagonal ZnS single-crystal nanowire arrays growing along the [110] direction via electrodeposition. The thermal expansion properties of the as-prepared ZnS nanowires have been studied by in situ x-ray diffraction method. The thermal expansion coefficient (TEC) of the ZnS nanowires decreases consistently from room temperature to 225°C where it reaches a minimum value, and then increases rapidly. The average TEC in the studied temperature range is 4.74×10−6/°C, which is smaller than that of the conventional bulk counterpart.
Nucleation of Micro Crack for Brittle Fracture in Magnetic Field
LIU Zhao-Long, HU Hai-Yun, FAN Tian-You, XING Xiu-San
Chin. Phys. Lett. 2010, 27 (10): 106202 .   DOI: 10.1088/0256-307X/27/10/106202
Abstract   PDF(pc) (403KB) ( 409 )
The influence of magnetic field on the nucleation of micro crack for brittle fracture is studied. The dynamic equation of micro crack in magnetic field is deducted. Using the crack model of a single pile-up group of dislocation, the growth speed of micro crack at a low growth speed stage is derived. To understand the effect of the magnetic field on the nucleation, the mean nucleation rate of micro crack in magnetic field is obtained. The derived result on the mean nucleation rate of micro crack shows that the applied magnetic field could change the mean nucleation rate of micro crack. The way in which the mean nucleation rate varies with the field depends not only on the field but also on the magneto properties of material.
First-Principles Based Model of Spin-state Phase Transition
WANG Xue-Li, WANG Chuan-Hui, TIAN Zhao-Ming, YIN Shi-Yan, YUAN Song-Liu
Chin. Phys. Lett. 2010, 27 (10): 107101 .   DOI: 10.1088/0256-307X/27/10/107101
Abstract   PDF(pc) (549KB) ( 414 )
The nature of spin-state phase transition is investigated with [Fe(C4H4N2)\{Pt(CN)4\]} that is a novel 3D Hofmann-like compound. The bistability of this system is obtained by the first-principles calculation. It is demonstrated that thermal expansion is the intrinsic force involved in spin-state transition. Based on these results, we suggest a thermal exciting bistable model of spin-state transition with a temperature dependent crystal-field splitting (CFS). Experimental evidence of spin-state phase transition coincides with our theoretical model. This model approaches something fundamental in the mechanism leading to the transition, and it is important in developing new and practical controllable quantum devices.
Anomalous Magneto-Transport Properties of Epitaxial Single-Crystal Bi Films on Si(111)
PANG Fei, YIN Shu-Li, LIANG Xue-Jin, CHEN Dong-Min
Chin. Phys. Lett. 2010, 27 (10): 107102 .   DOI: 10.1088/0256-307X/27/10/107102
Abstract   PDF(pc) (670KB) ( 501 )
Anomalous transport properties of 40-nm-thick single-crystal Bi(111) films grown on Si(111)-7 substrates is investigated. The magnetoresistance (MR) of the films in perpendicular magnetic field shows a regular positive behavior in the temperature range 2−300 K, the MR in parallel field (B||) displays a series of interesting features. Specifically, we observe a change of the MR (B||) behavior from positive to negative when the temperature is below 10 K. In the range 10−170 K, the MR (B||) is negative in the investigated field of 9 T. When T>170 K, a positive MR appears in the high field regime. The low temperature MR(B||) behavior in the parallel field can be understood by the competition between weak localization and weak anti-localization (WAL). Furthermore, our results suggest that the WAL is dominated by the interface carriers.
Bipolarons in Organic Electroluminescence
JIANG Qing Yun, LI Sheng, Thomas F. George, SUN Xin
Chin. Phys. Lett. 2010, 27 (10): 107301 .   DOI: 10.1088/0256-307X/27/10/107301
Abstract   PDF(pc) (1386KB) ( 386 )
We investigate the bipolaron channel B++ +B--→BX. The dynamical evolutions and transition probabilities of this bipolaron luminescence channel are studied. It is found that this channel avoids the triplet and is able to enhance the efficiency. We suggest that choosing certain polymers and injection structures, in which B is easily formed, can improve the luminescence efficiency. It is believed that these results will motivate further experimental studies about the function of bipolarons in electroluminescence.
Enhanced Performance of Phase Change Memory Cell Element by Initial Operation and Non-Cumulative Programming
CHEN Yi-Feng, SONG Zhi-Tang, CHEN Xiao-Gang, LIU Bo, XU Cheng, FENG Gao-Ming, WANG Liang-Yong, ZHONG Min, FENG Song-Lin
Chin. Phys. Lett. 2010, 27 (10): 107302 .   DOI: 10.1088/0256-307X/27/10/107302
Abstract   PDF(pc) (713KB) ( 398 )
A phase change memory (PCM) device, based on the Ge2Sb2Te5 (GST) material, is fabricated using the standard 0.18−μm CMOS technology. After serials of detailed experiments on the phase transition behaviors, we find that the RESET process is strongly dependent on the state of the inactive area and the active area affects the SET process dramatically. By applying a 5−mA current-voltage (I-V) sweep as initial operation, we can reduce the voltage drop beyond the active area during the RESET process and the overall RESET voltage decreases from 3 V plus to 2.5 V. For the SET operation, a non−cumulative programming method is introduced to eliminate the impact of randomly formed amorphous active area, which is strongly related to the threshold switching process and SET voltage. Combining the two methods, the endurance performance of the PCM device has been remarkably improved beyond 1×106 cycles.
Resonance Transmission in Graphene-Nanoribbon-Based Quantum Dot and Superlattice
XU Ning, WANG Bao-Lin, SUN Hou-Qian, DING Jian-Wen
Chin. Phys. Lett. 2010, 27 (10): 107303 .   DOI: 10.1088/0256-307X/27/10/107303
Abstract   PDF(pc) (655KB) ( 643 )
By using a decomposition elimination method for Green's function, the transport properties of Graphene-nanoribbon-based quantum dot (QD) and/or QD superlattice are studied. It is shown that relatively small changes of both QD size and magnetic field intensity can induce strong variations in the electron transmission across the structure. For a QD device, electrons can be either totally reflected or totally transmitted through the QD region at some energies, and the quasibound peaks have been observed to have a small shift due to quasibound state energy varying. In the case of QD superlattice, the electrons within the miniband energy region can transmit through a device, similar to a QD device. Therefore, the transmission spectrum can be tailored to match with requirement by modulating the size of quantum dot and the number p of superlattce.
Rectifying and Photovoltage Properties of ZnO:Al/p-Si Heterojunction
MA Jing-Jing, JIN Ke-Xin, LUO Bing-Cheng, FAN Fei, XING Hui, ZHOU Chao-Chao, CHEN Chang-Le
Chin. Phys. Lett. 2010, 27 (10): 107304 .   DOI: 10.1088/0256-307X/27/10/107304
Abstract   PDF(pc) (628KB) ( 2057 )
An Al-doped ZnO/p-Si heterojunction is fabricated by a laser molecular beam epitaxy technique. The abnormally high ideality factors (n≫2) of the prepared heterojunction are observed in the interim bias voltage range. A theoretical model is proposed to understand the much higher ideality factor of the special heterojunction diode. The ZnO:Al film shows metal−like conductivity with the electrical resistivity about 6.56×10-4⋅Ω⋅cm at room temperature. The temperature dependence of the photovoltage indicates that the photovoltaic effect of the Al-doped ZnO based heterojunction can be changed by the intrinsic metal-semiconductor transition at 120 K.
Label-Free and High-Throughput Detection of Protein Microarrays by Oblique-Incidence Reflectivity Difference Method
WANG Xu, LU Heng, WEN Juan, YUAN Kun, LÜ, Hui-Bin, JIN Kui-Juan, ZHOU Yue-Liang, YANG Guo-Zhen,
Chin. Phys. Lett. 2010, 27 (10): 107801 .   DOI: 10.1088/0256-307X/27/10/107801
Abstract   PDF(pc) (998KB) ( 423 )
We label-free detected the biological process of preparing a microarray that includes 400 spots of mouse immunoglobulin G (IgG) as well as the specific hybridization between mouse IgG and goat anti-mouse IgG by an oblique-incidence reflectivity difference (OI-RD) method. The detection results after each process including printing, washing, blocking, and hybridization, demonstrate that the OI-RD method can trace the preparation process of a microarray and detect the specific hybridization between antigens and antibodies. OI-RD is a promising method for label-free and high-throughput detection of biological microarrays.
Preparation and Characterization of Grain Size Controlled LaB6 Polycrystalline Cathode Material
BAO Li-Hong, ZHANG Jiu-Xing, ZHOU Shen-Lin, WEI Yong-Feng
Chin. Phys. Lett. 2010, 27 (10): 107901 .   DOI: 10.1088/0256-307X/27/10/107901
Abstract   PDF(pc) (930KB) ( 1023 )
The grain size controlled bulk Lanthanum hexaboride (LaB6) cathode material was prepared by using the spark plasma sintering method in an oxygen free system. The starting precursor nanopowders with average grain size of 50 nm were prepared by high−energy ball milling. The nanopowder was fully densified at 1300°C, which is about 350°C lower than the sintering temperature of the coarse powders. The thermionic emission current density was measured to be 42.0 A/cm2, which is much higher than 24.2 A/cm2 of coarse powders and Vickers hardness to be 1860 kg/mm2, which is also higher than 1700 kg/mm2 of coarse one. These results indicate that refining the powder grain size to nano level was beneficial for reducing the sintering temperature and promoting the thermionic emission and mechanic properties.
Si3.5Sb2Te3 Phase Change Material for Low-Power Phase Change Memory Application
REN Kun, RAO Feng, SONG Zhi-Tang, WU Liang-Cai, ZHOU Xi-Lin, XIA Meng-Jiao, LIU Bo, FENG Song-Lin, XI Wei, YAO Dong-Ning, CHEN Bomy
Chin. Phys. Lett. 2010, 27 (10): 108101 .   DOI: 10.1088/0256-307X/27/10/108101
Abstract   PDF(pc) (662KB) ( 479 )
Novel Si3.5Sb2Te3 phase change material for phase change memory is prepared by sputtering of Si and Sb2Te3 alloy targets. Crystalline Si3.5Sb2Te3 is a stable composite material consisting of amorphous Si and crystalline Sb2Te3, without separated Te phase. The thermally stable Si3.5Sb2Te3 material has data retention ability (10 years at 412 K) better than that of the Ge2Sb2Te5 material (10 years at 383 K). Phase change memory device based on Si3.5Sb2Te3 is successfully fabricated, showing low power consumption. Up to 2.2×107 cycles of endurance have been achieved with a resistance ratio lager than 300.
Nanoadhesion of a Power-Law Graded Elastic Material
CHEN Shao-Hua, CHEN Pei-Jian
Chin. Phys. Lett. 2010, 27 (10): 108102 .   DOI: 10.1088/0256-307X/27/10/108102
Abstract   PDF(pc) (458KB) ( 448 )
The Dugdale-Barenblatt model is used to analyze the adhesion of graded elastic materials at the nanoscale with Young's modulus E varying with depth z according to a power law E=E0 (z/c0)k (0<k<1) while Poisson's ratio ν remains a constant, where E0 is a referenced Young's modulus, k is the gradient exponent and c0 is a characteristic length describing the variation rate of Young's modulus. We show that, when the size of a rigid punch becomes smaller than a critical length, the adhesive interface between the punch and the graded material detaches due to rupture with uniform stresses, rather than by crack propagation with stress concentration. The critical length can be reduced to the one for isotropic elastic materials only if the gradient exponent k vanishes.
Effects of Substrate Temperature and Vacuum Annealing on Properties of ITO Films Prepared by Radio-Frquency Magnetron Sputtering
N. Boonyopakorn, N. Sripongpun, C. Thanachayanont, S. Dangtip,
Chin. Phys. Lett. 2010, 27 (10): 108103 .   DOI: 10.1088/0256-307X/27/10/108103
Abstract   PDF(pc) (760KB) ( 1585 )
Indium tin oxide (ITO) films were prepared by rf magnetron sputtering under two conditions: (i) at substrate temperature Ts from room temperature (RT) to 350°C, (ii) with additional post−annealing in vacuum at 400°C for 30 min in comparison of their crystalline structures, and electrical−optical properties of the films deposited. From the experimental results, it is found that, under the first condition, the crystalline structures and the electrical-optical properties of the films are improved with the increasing Ts. Under the other condition, i.e. with the additional post−annealing, the films exhibit higher degree of crystallinities and better electrical-optical properties. Under the two deposition conditions, inter-relation between electrical-optical properties and the crystalline structure is observed clearly. However, even under the same annealing condition, it is observed that improved properties of the films are different, depending on their deposition temperatures, which implies that an initial stage of the ITO film before annealing is an important factor for the film's properties improved after annealing. The resistivity of 2.33×10-4 Ω⋅cm can be achieved at Ts of 350°C after annealing.
Optical Properties of Rhodamine 6G Doped AlPO4 Gel
LI Ri-Hong, TANG Bin, FAN You-Yu, REN Jin-Jun, ZHANG Long
Chin. Phys. Lett. 2010, 27 (10): 108201 .   DOI: 10.1088/0256-307X/27/10/108201
Abstract   PDF(pc) (661KB) ( 661 )
Homogeneous monolith of AlPO4 gel doped with rhodamine 6G (Rh6G) at different dye loadings is prepared by a one−step process with sol-gel method using the precursors Al(lact)3 and H3PO4. The optical properties of AlPO4 gel doped with Rh6G are characterized by UV−Visible absorption spectra and fluorescence spectra. Rh6G molecular J-dimers and H-dimers even multimers are analyzed by excitation spectra based on exciton theory. The AlPO4 gel doped with Rh6G dye with molar ratio of Rh6G/Al(lact)3 of 1×10−4 has excellent optical properties without obvious aggregates.
Ultrasensitive Detection of Infrared Photon Using Microcantilever: Theoretical Analysis
CAO Li-Xin, ZHANG Feng-Xin, ZHU Yin-Fang, YANG Jin-Ling,
Chin. Phys. Lett. 2010, 27 (10): 108501 .   DOI: 10.1088/0256-307X/27/10/108501
Abstract   PDF(pc) (477KB) ( 531 )
We present a new method for detecting near-infrared, mid-infrared, and far-infrared photons with an ultra-high sensitivity. The infrared photon detection was carried out by monitoring the displacement change of a vibrating microcantilever under light pressure using a laser Doppler vibrometer. Ultrathin silicon cantilevers with high sensitivity were produced using micro/nano-fabrication technology. The photon detection system was set up. The response of the microcantilever to the photon illumination is theoretically estimated, and a nanowatt resolution for the infrared photon detection is expected at room temperature with this method.
Optical Trapping of Double-Ring Radially Polarized Beam with Improved Axial Trapping Efficiency
YAO Bao-Li, YAN Shao-Hui, YE Tong, ZHAO Wei
Chin. Phys. Lett. 2010, 27 (10): 108701 .   DOI: 10.1088/0256-307X/27/10/108701
Abstract   PDF(pc) (560KB) ( 483 )
Radially polarized beams, focused by a high numerical aperture (NA) objective, have non-propagating fields along the propagation axis in the focal region, which leads to a higher axial trapping efficiency in comparison with linearly polarized beams. We propose a design for converting a lowest-order radially polarized beam (R-TEM01) to a double−ring radial polarization distribution (DR R-TEM01) through a specially designed polarization rotator. The phases of the two rings of this beam differ by π. Numerical results evaluated by rigorous T−matrix method show that the DR R-TEM01 beam can improve the axial trapping efficiency compared with the R−TEM01 beam, provided that the size of trapped particles is of order of the wavelength of the beam.
Accelerating Consensus by Preferential Words in the Naming Game
ZHUANG Yong, LIU Run-Ran, YANG Han-Xin, SHI Dong-Mei, WANG Bing-Hong,
Chin. Phys. Lett. 2010, 27 (10): 108901 .   DOI: 10.1088/0256-307X/27/10/108901
Abstract   PDF(pc) (661KB) ( 455 )
The naming game is a model of nonequilibrium dynamics for the self-organized emergence of a language or a communication system. We study a modified version of the minimal naming game in which the speaker selects a word from its inventory with a probability proportional to exp(Rs*α), where Rs is the success ratio of the name and α is a tunable parameter. By investigating the effects of α on the evolutionary processes for both square lattice and scale−free networks, we find that the convergence time decreases with the increasing α on both two networks, which indicates that preferential selection of successful words can accelerate the reaching of consensus. More interestingly, for α>0, we find that the relation between convergence time and α exhibits a power-law form.
Optimal Capacity Allocation on Heterogeneous Complex Transport Networks
LIU Wei-Kai, GUAN Zhi-Hong, LIAO Rui-Quan
Chin. Phys. Lett. 2010, 27 (10): 108902 .   DOI: 10.1088/0256-307X/27/10/108902
Abstract   PDF(pc) (471KB) ( 441 )
We study how the node delivering capacity is allocated so that the traffic transport efficiency can be enhanced maximally. Network heterogeneity of degree distribution and processing delay of the traffic are considered. An explicit analytical solution is provided, which is based on the M/M/1 queueing theory and optimization principle, provided that the network structure and routing strategy are given. In particular, we extend the relevant conclusions in the literature [Eurphys. Lett. 83 (2008) 28001]. Finally, an order parameter simulation example by comparing results with those obtained via simple capacity allocation in large Barabasi-Albert (BA) scale-free network is provided to illustrate the effectiveness of the theoretical results
62 articles