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Volume 26 Issue 10
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GENERAL
Approximate Symmetry Reduction and Infinite Series Solutions to the Nonlinear Wave Equation with Damping
ZHAO Yuan, ZHANG Shun-Li, LOU Sen-Yue,
Chin. Phys. Lett. 2009, 26 (10): 100201 .   DOI: 10.1088/0256-307X/26/10/100201
Abstract   PDF(pc) (207KB) ( 735 )
The approximate symmetry perturbation method is applied to the nonlinear damped wave equation. The approximate symmetry reduction equations of different orders are derived and the corresponding series reduction solutions are obtained.
Quantum Correlation Coefficients for Angular Coherent States
CHEN Wei, HE Yan, GUO Hao
Chin. Phys. Lett. 2009, 26 (10): 100202 .   DOI: 10.1088/0256-307X/26/10/100202
Abstract   PDF(pc) (186KB) ( 639 )
Quantum covariance and correlation coefficients of angular or SU(2) coherent states are directly calculated for all irreducible unitary representations. These results explicitly verify that the angular coherent states minimize the Robertson-Schrodinger uncertainty relation for all spins, which means that they are the so-called intelligent states. The same results can be obtained by the Schwinger representation approach.
Nearly Deterministic Teleportation of a Photonic Qubit with Weak Cross-Kerr Nonlinearities
ZHOU Jian, YANG Ming, LU Yan, CAO Zhuo-Liang,
Chin. Phys. Lett. 2009, 26 (10): 100301 .   DOI: 10.1088/0256-307X/26/10/100301
Abstract   PDF(pc) (284KB) ( 441 )
Scheme for teleporting an unknown single-qubit photonic state is revisited. With the help of quantum nondemolition measurements, the scheme now can be achieved in an almost deterministic way. The weak-cross-Kerr-nonlinearities-based quantum nondemolition measurement acts as an entangler as well as the Bell-state analyzer, and thus plays a similar role as the CNOT gate in the teleportation process. This improvement makes the present scheme more efficient than the schemes using nonunitary projective measurements and feasible with the current experimental technology.
Approximate Solutions of the Schrödinger Equation for the Eckart Potential and Its Parity-Time-Symmetric Version Including Centrifugal Term
ZHANG Ai-Ping, QIANG Wen-Chao, LING Ya-Wen
Chin. Phys. Lett. 2009, 26 (10): 100302 .   DOI: 10.1088/0256-307X/26/10/100302
Abstract   PDF(pc) (254KB) ( 443 )
The energy eigenvalues and eigenfunctions of the Schrödinger equation for Eckart potential as well as the parity-time-symmetric version of the potential in three dimensions with the centrifugal term are investigated approximately by using the Nikiforov-Uvarov method. To show the accuracy of our results, we calculate the energy eigenvalues for various values of n and l. It is found that the results are in good agreement with the numerical solutions for short-range potential (large a). For the case of 1/a i/a, the potential is also studied briefly.
Inseparability of Phase-Damped Bipartite Gaussian States
JIANG Li-Zhen
Chin. Phys. Lett. 2009, 26 (10): 100303 .   DOI: 10.1088/0256-307X/26/10/100303
Abstract   PDF(pc) (326KB) ( 546 )
For bipartite non-Gaussian states which are prepared by applying the phase damping to Gaussian states, we use Fock subspace inseparable criterion and the Shchukin-Vogel inseparable criterion to analyze their inseparability. The lowest order of the two criteria is obtained. Fock subspace criterion is more efficient in detecting the entanglement of damped Gaussian state by numerical results. Two photon Fock subspace criterion does not improve the entanglement detecting condition.
Quantum Gate Operations in Decoherence-Free Subspace with Superconducting Charge Qubits inside a Cavity
WANG Yi-Min, ZHOU Yan-Li, LIANG Lin-Mei, LI Cheng-Zu
Chin. Phys. Lett. 2009, 26 (10): 100304 .   DOI: 10.1088/0256-307X/26/10/100304
Abstract   PDF(pc) (270KB) ( 444 )
We propose a feasible scheme to achieve universal quantum gate operations in decoherence-free subspace with superconducting charge qubits placed in a microwave cavity. Single-logic-qubit gates can be realized with cavity assisted interaction, which possesses the advantages of unconventional geometric gate operation. The two-logic-qubit controlled-phase gate between subsystems can be constructed with the help of a variable electrostatic transformer. The collective decoherence can be successfully avoided in our well-designed system. Moreover, GHZ state for logical qubits can also be easily produced in this system.
Cryptanalysis of an Improved Flexible Ping-Pong Protocol in Perfect and Imperfect Quantum Channels
ZHANG Bin-Bin, WANG Da-Qing, HUANG Shan-Shan, LIU Yu
Chin. Phys. Lett. 2009, 26 (10): 100305 .   DOI: 10.1088/0256-307X/26/10/100305
Abstract   PDF(pc) (230KB) ( 546 )
We recently proposed a flexible quantum secure direct communication protocol [Chin. Phys. Lett. 23(2006)3152]. By analyzing its security in the perfect channel from the aspect of quantum information theory, we find that an eavesdropper is capable of stealing all the information without being detected. Two typical attacks are presented to illustrate this point. A solution to this loophole is also suggested and we show its powerfulness against the most general individual attack in the ideal case. We also discuss the security in the imperfect case when there is noise and loss.
Quantum Swap Gate with Molecular Ensembles via Cavity Quantum Electrodynamics
LIU Yan-Sheng, LIANG Lin-Mei
Chin. Phys. Lett. 2009, 26 (10): 100306 .   DOI: 10.1088/0256-307X/26/10/100306
Abstract   PDF(pc) (232KB) ( 607 )
We present a simple method to realize a swap gate at one step with two molecular ensembles in a stripline cavity. In this scheme, we can benefit from the enhancement of the coherent coupling and acquire a long coherent time with encoding qubits in different spin states of the rotational ground state in the molecular ensembles. As a by-product, a scheme to create an entangled state with one excitation stored in two ensembles is proposed.
General Theory of Decoy-State Quantum Cryptography with Dark Count Rate Fluctuation
GAO Xiang, SUN Shi-Hai, LIANG Lin-Mei
Chin. Phys. Lett. 2009, 26 (10): 100307 .   DOI: 10.1088/0256-307X/26/10/100307
Abstract   PDF(pc) (237KB) ( 652 )
The existing theory of decoy-state quantum cryptography assumes that the dark count rate is a constant, but in practice there exists fluctuation. We develop a new scheme of the decoy state, achieve a more practical key generation rate in the presence of fluctuation of the dark count rate, and compare the result with the result of the decoy-state without fluctuation. It is found that the key generation rate and maximal secure distance will be decreased under the influence of the fluctuation of the dark count rate.
Fermions Tunneling from Non-Stationary Dilaton-Maxwell Black Hole via General Tortoise Coordinate Transformation
LIN Kai, YANG Shu-Zheng
Chin. Phys. Lett. 2009, 26 (10): 100401 .   DOI: 10.1088/0256-307X/26/10/100401
Abstract   PDF(pc) (210KB) ( 482 )
Fermions tunneling of the non-stationary Dilaton-Maxwell black hole is investigated with general tortoise coordinate transformation. The Dirac equation is simplified by semiclassical approximation so that the Hamilton-Jacobi equation is generated. Finally the tunneling rate and the Hawking temperature is calculated.
Thermodynamic Properties of Higher-Dimensional RN Black Holes
WEI Yi-Huan
Chin. Phys. Lett. 2009, 26 (10): 100402 .   DOI: 10.1088/0256-307X/26/10/100402
Abstract   PDF(pc) (176KB) ( 610 )
A general calculation formula of the heat capacity for the HRN black holes is derived. The heat capacities for Q, Φ+ and r- fixed are obtained. Assuming that the charge-mass ratio of fluctuation modes does not exceed the extremal value, the minimum charge-mass ratio of the black holes for which the heat capacity is positive is determined.
Chaos in the Fractional Order Generalized Lorenz Canonical Form
YANG Yun-Qing, CHEN Yong,
Chin. Phys. Lett. 2009, 26 (10): 100501 .   DOI: 10.1088/0256-307X/26/10/100501
Abstract   PDF(pc) (861KB) ( 672 )
A fractional-order generalized Lorenz system is constructed and numerically investigated. Chaotic behavior existing in the fractional-order generalized Lorenz system is found. The numerical simulations and interesting figures are performed.
A Novel Adaptive Predictor for Chaotic Time Series
BU Yun, WEN Guang-Jun, ZHOU Xiao-Jia, ZHANG Qiang
Chin. Phys. Lett. 2009, 26 (10): 100502 .   DOI: 10.1088/0256-307X/26/10/100502
Abstract   PDF(pc) (399KB) ( 600 )
Many chaotic time series show non-Gaussian distribution, and non-Gaussianity can be characterized not only by higher-order cumulants but also by negative entropy. Since negative entropy can be accurately approximated by some special non-polynomial functions, which also can form an orthogonal system, these functions are used to construct an adaptive predictor to replace higher-order cumulants. Simulation shows the algorithm performs well for different chaotic systems.
Tracking Desired Trajectory in a Vibro-Impact System Using Backstepping Design
WANG Liang, XU Wei, ZHAO Rui, SUN Chun-Yan, GUO Yong-Feng
Chin. Phys. Lett. 2009, 26 (10): 100503 .   DOI: 10.1088/0256-307X/26/10/100503
Abstract   PDF(pc) (422KB) ( 482 )
Based on the backstepping design of smooth systems, we developed a new control law to achieve chaos control for a vibro-impact system. In our control strategy, a novel and effective controller is designed such that the output of the vibro-impact system can track any desired trajectory in its domain. The single-degree-of-freedom vibro-impact system is taken as an example to show this control procedure. Numerical simulations are provided to verify the effectiveness of the proposed method.
Stochastic Resonance in a Time-Delayed Mono-Stable System with Multiplicative and Additive Noise
GUO Feng, HUANG Zhi-Qi, FAN Yong, LI Shao-Fu, ZHANG Yu
Chin. Phys. Lett. 2009, 26 (10): 100504 .   DOI: 10.1088/0256-307X/26/10/100504
Abstract   PDF(pc) (286KB) ( 686 )
The stochastic resonance (SR) in a time-delayed mono-stable system driven by multiplicative white noise, additive white noise, additive dichotomous noise as well as a periodic square-wave signal is considered from the view of the signal-to-noise ratio (SNR). It is found that the SNR increases monotonically with the increase of the delay time. The SNR exhibits the SR behavior when it is plotted as a function of intensities of the noises, displaying the asymmetry of the dichotomous noise. The SNR varies non-monotonically with the increase of the system parameter and the amplitude of the input square-wave signal.
Stochastic Resonance in a Spatially Symmetric and Flashing Periodic Potential Subjected to Correlated Noises
NIE Lin-Ru, GONG Yu-Lan, MEI Dong-Cheng
Chin. Phys. Lett. 2009, 26 (10): 100505 .   DOI: 10.1088/0256-307X/26/10/100505
Abstract   PDF(pc) (349KB) ( 529 )
A Brownian particle in a spatially symmetric and flashing periodic potential subjected to correlated noises is investigated. The exact expression of its current is analytically derived. The numerical results indicate that its current as a function of noise intensity exhibits two peaks in the case of positive correlations, and two vales in the case of negative correlations, i.e., a novel stochastic resonance (SR) phenomenon. The SR is attributed to the harmonic cooperation between the noises and the flashing periodic potential. The conditions under which the SR occurs are also presented.
Super-High Resolution Time Interval Measurement Method Based on Time-Space Relationships
DU Bao-Qiang, ZHOU Wei
Chin. Phys. Lett. 2009, 26 (10): 100601 .   DOI: 10.1088/0256-307X/26/10/100601
Abstract   PDF(pc) (295KB) ( 575 )
Based on the principle of quantized delay-time, a super-high resolution time interval measurement method is proposed based on time-space relationships. Using the delay-time stability that time and frequency signal travel in a specific medium, the measured time interval can be quantized. Combined with the phase coincidence detection technique, the measurement of time can be changed into the measurement of space length. The resolution and the stability of the measurement system are easily improved. Experimental results show that the measurement resolution of the measured time interval depends on the length difference of the double delay-time unit. When the length difference is set up on millimeter level or sub-millimeter level, super-high measurement resolution from hundreds of picosecond to tens of picosecond can be obtained.
Nanoscale Thermal Response in ZnO Varistors by Atomic Force Microscopy
ZHAO Kun-Yu, ZENG Hua-Rong, LI Guo-Rong, SONG Hong-Zhang, CHENG Li-Hong, HUI Sen-Xing, YIN Qing-Rui
Chin. Phys. Lett. 2009, 26 (10): 100701 .   DOI: 10.1088/0256-307X/26/10/100701
Abstract   PDF(pc) (894KB) ( 576 )
We report the application of customer-built scanning thermal microscopy (SThM) based on a commercial atomic force microscope to investigate local thermal inhomogeneity of ZnO varistors. The so-called 3ω method, generally used for measuring macroscale thermal conductivity, is set up and integrated with an atomic force microscope to probe the nanoscale thermal property. Remarkably, thermal contrasts of ZnO varistors are firstly imaged by the SThM, indicating the uniform distribution of spinel phases at triple points. The frequency-dependent thermal signal of ZnO varistors is also studied to present quantitative evaluation of local thermal conductivity of the sample.
In/Pd-Doped SnO2-Based CO Micro-Structure Sensor with High Sensitivity and Quick Response
LIU Li, ZHANG Tong, LI Shou-Chun, WANG Lian-Yuan, FAN Hui-Tao, LI Wei
Chin. Phys. Lett. 2009, 26 (10): 100702 .   DOI: 10.1088/0256-307X/26/10/100702
Abstract   PDF(pc) (899KB) ( 673 )
In/Pd-doped SnO2 is synthesized via a sol-gel method and coated on a silicon substrate with Pt electrodes to fabricate a micro-structure sensor. The sensor can be used to detect CO down to 1ppm (the sensitivity is about 3), and the response time and recovery time are about 5 and 15s, respectively. Excellent selectivity is also found based on our sensor. These results demonstrate a promising approach to fabricate high-performance CO sensors with high sensitivity and quick response.
Higher Harmonics Generation in Tapping Mode Atomic Force Microscope
LI Yuan, QIAN Jian-Qiang
Chin. Phys. Lett. 2009, 26 (10): 100703 .   DOI: 10.1088/0256-307X/26/10/100703
Abstract   PDF(pc) (275KB) ( 579 )
The contribution of higher harmonics to the movement of a micro rectangular cantilever in tapping mode AFM is investigated. The dependence between the phase lag of the higher harmonic components and tip-sample separation are found to be an order of magnitude higher than the base one, reflecting an increasing sensitivity to local variations of surface properties compared to the normal phase signal. The strong correlation between the higher harmonic amplitude and average sample deformation implies that the higher harmonic amplitude can be taken to monitor the tapping force or as feedback variable to fulfill a constant repulsive force mode.
THE PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
Top Quark Decay t → cbb- in Topcolor-Assisted Technicolor Models
LIU Guo-Li
Chin. Phys. Lett. 2009, 26 (10): 101401 .   DOI: 10.1088/0256-307X/26/10/101401
Abstract   PDF(pc) (266KB) ( 566 )
The topcolor-assisted technicolor (TC2) model predicts the existence of the top-pions and the CP-even top-Higgs with large flavor-changing couplings to the top quark, which at tree-level can mediate the top quark three-body decay t → cbb-. We study this decay, show the dependence of the decay rate on the relevant TC2 parameters and compare the results with the predictions in the minimal supersymmetric model. We find that the decay rate in the TC2 model is much larger than that in the minimal supersymmetric model if the new particles are not too heavy. However, in consideration of the CDF and the LEP experiment limits, the top-pion mass is greater than 340GeV in a more realistic parameter space, so the decay width of the channel t → cbb- intermediated by top-pions will be depressed greatly and difficult to be detected at the future collider. Thus, to observe this channel at the future collider, considering the top-higgs contribution may be the possible way when the masses of the top-pions and the top-higgs are not degenerate.
NUCLEAR PHYSICS
Transverse Momentum and Rapidity Distributions of Φ Mesons Produced in Pb-Pb Collisions at SPS Energies
MENG Cai-Rong
Chin. Phys. Lett. 2009, 26 (10): 102501 .   DOI: 10.1088/0256-307X/26/10/102501
Abstract   PDF(pc) (241KB) ( 504 )
To investigate the excitation degree of the interacting system and the penetrating power of the projectile nucleus and to understand their dependences on incident energy, the transverse momentum and rapidity distributions of particles produced in nucleus-nucleus collisions at high energies are studied by using a multisource ideal gas model. The calculated results are compared with the most recent NA49 experimental data of Φ mesons produced in Pb-Pb collisions at the Super Proton Synchrotron (SPS) energies.
ATOMIC AND MOLECULAR PHYSICS
Coherent Control of Population Transfer in Li Atoms via Chirped Microwave Pulses
JIA Guang-Rui, ZHANG Ji-Cai, ZHANG Xian-Zhou, REN Zhen-Zhong
Chin. Phys. Lett. 2009, 26 (10): 103201 .   DOI: 10.1088/0256-307X/26/10/103201
Abstract   PDF(pc) (478KB) ( 550 )
We demonstrate theoretically that Li atoms can be transferred to states of a lower principal quantum number by exposing them to a frequency chirped microwave pulse. The population transfer of Li atoms from the n=75 state to n=70 with more than 90% efficiency is achieved by means of the sequential single-photon ∆ n=-1 transitions. The calculation fully utilizes all of the available orbital angular momentum l states for a given n, and the interference pattern and population evolution dynamics of individual l states are analyzed in detail. Using the time-dependent multilevel approach, we describe the process reasonably well as a sequence of adiabatic rapid passages.
Measurement of 16O5+ Induced L X-Ray Production Cross Sections for Gold
YANG Zhi-Hu, DU Shu-Bin, CHANG Hong-Wei, XUE Ying-Li, SONG Zhang-Yong, ZHANG Bo-Li, ZHU Ke-Xin, YU De-Yang, CAI Xiao Hong
Chin. Phys. Lett. 2009, 26 (10): 103202 .   DOI: 10.1088/0256-307X/26/10/103202
Abstract   PDF(pc) (460KB) ( 512 )
The characteristic Ll, Lα, Lβ and Lγ x-rays of Au and energy shifts produced by 20-50MeV 16O5+ beams on a thick Au film are measured with a Si (Li)detector. Cross-section ratios of σ(Ll)/σ(Lα), σ(Lβ)/σ(Lα) and σ(Lγ)/σ(Lα) versus O5+ energy show that consistent calculations yield considerably better agreements. Energy shifts Ll, Lα, Lβ and Lγ x-rays of Au target increase with more incidence energy. The main application for these measurements is multi-element trace analysis through particle induced x-ray emission.
Photodissociation Efficiency Spectroscopy Study of the Rydberg Excited Ion-Pair States of Carbon Dioxide
FENG Qiang, XU Yun-Feng, SUN Jin-Da, TIAN Shan-Xi, SHAN Xiao-Bin, LIU Fu-Yi, SHENG Liu-Si
Chin. Phys. Lett. 2009, 26 (10): 103401 .   DOI: 10.1088/0256-307X/26/10/103401
Abstract   PDF(pc) (332KB) ( 546 )
Photodissociation efficiency spectrum of anionic oxygen atom produced via ion-pair dissociations of carbon dioxide is recorded by means of the synchrotron radiation excitation (XUV photon energy 17.40-20.00eV). The present spectrum is assigned as the Rydberg-like excited ion-pair states, i.e., Tanaka-Ogawa and Henning series, ~C2g+ (CO2+) vibrational ground-state and excitation series. Three Rydberg series, npσu, npπu, and nfu, converging to ~C2g+ (0,0,0), show the higher cross sections.
FUNDAMENTAL AREAS OF PHENOMENOLOGY(INCLUDING APPLICATIONS)
High Directive Cavity Antenna Based on One-Dimensional LHM-RHM Resonator
JIANG Tao, CUI Wan-Zhao, MA Wei, YUAN Yu, WANG Dong-Xing, RANLi-Xin
Chin. Phys. Lett. 2009, 26 (10): 104101 .   DOI: 10.1088/0256-307X/26/10/104101
Abstract   PDF(pc) (1120KB) ( 688 )
We propose a novel kind of cavity antenna based on a one-dimensional LHM-RHM cavity resonator. The resonance condition for such a cavity resonator is analytically presented. It is proved that the thickness of the antenna can be much smaller than the working wavelength. The simulation and experimental results for our cavity antenna agree with the theoretical prediction with relatively high directivity.
Schemes for Generating Cluster States via Cavity Systems
DU Gang, LAI Bo-Hui, YU Ya-Fei, ZHANG Zhi-Ming
Chin. Phys. Lett. 2009, 26 (10): 104201 .   DOI: 10.1088/0256-307X/26/10/104201
Abstract   PDF(pc) (222KB) ( 648 )
We propose a scheme for generating an N-atom cluster state via cavity quantum electrodynamics (CQED). In our scheme, there is no transfer of quantum information between the atoms and the cavity, i.e., the cavity is always in the vacuum state, so the cavity decay can be suppressed. Also, the generated cluster state is the entanglement of the ground states, so the atomic spontaneous emission can be avoided. Therefore, the cluster state generated in our scheme has a longer lifetime. Furthermore, the requirement on the quality factor of the cavity greatly loosened for the cavity is only virtually excited.
Equivalent Method of Solving Quantum Efficiency of Reflection-Mode Exponential Doping GaAs Photocathode
NIU Jun, YANG Zhi, CHANG Ben-Kang
Chin. Phys. Lett. 2009, 26 (10): 104202 .   DOI: 10.1088/0256-307X/26/10/104202
Abstract   PDF(pc) (252KB) ( 739 )
The mathematical expression of the electron diffusion and drift length LDE of exponential doping photocathode is deduced. In the quantum efficiency equation of the reflection-mode uniform doping cathode, substituting LDE for LD, the equivalent quantum efficiency equation of the reflection-mode exponential doping cathode is obtained. By using the equivalent equation, theoretical simulation and experimental analysis shows that the equivalent index formula and formula-doped cathode quantum efficiency results in line. The equivalent equation avoids complicated calculation, thereby simplifies the process of solving the quantum efficiency of exponential doping photocathode.
Scattering from a Multi-Layered Sphere Located in a High-Order Hermite-Gaussian Beam
LI Hai-Ying, WU Zhen-Sen, LI Zheng-Jun
Chin. Phys. Lett. 2009, 26 (10): 104203 .   DOI: 10.1088/0256-307X/26/10/104203
Abstract   PDF(pc) (450KB) ( 618 )
Scattering of a high-order Hermite-Gaussian beam by a multi-layered sphere is analyzed. The incident high-order Hermite-Gaussian beam field is expressed by the complex-source-point method and expanded in terms of spherical vector wave functions. The beam shape coefficients of the Hermite-Gaussian beam are obtained. Under electromagnetic field boundary conditions, coefficients in the expressions of scattering fields are derived. Results of the numerical calculation of scattering intensity are presented. The effects of the particle parameters and beam parameters on scattering intensity are discussed in detail.
Narrow Band Longitude Mode Selector of Laser Based on Conjugated Photonic Crystals
WANG Zhao-Na, LIU Da-He
Chin. Phys. Lett. 2009, 26 (10): 104204 .   DOI: 10.1088/0256-307X/26/10/104204
Abstract   PDF(pc) (244KB) ( 563 )
Properties of transmission spectra of multi-layers consisting of two conjugated photonic crystals are investigated. It is found that, in the case of a small amount of time, the mode density at the interface mode is much larger than that at the band edge. Under certain conditions, the transmission can reach the unity, and the bandwidth can reach the order of picometer. Based on this property, a longitude mode selector of laser consisting of two conjugated photonic crystals made with gain materials is suggested. The effects of the impedance contrast of materials and the refractive index of the environment on the bandwidth are studied.
Polarization Dependence of Linewidth Enhancement Factor in Semiconductor Optical Amplifier and Its Implication for Nonlinear Polarization Rotation
ZHAO Shuang, WU Chong-Qing, WANG Yong-Jun
Chin. Phys. Lett. 2009, 26 (10): 104205 .   DOI: 10.1088/0256-307X/26/10/104205
Abstract   PDF(pc) (520KB) ( 741 )
Linewidth enhancement factors (LEFs) of the transverse electric mode and the transverse magnetic mode in bulk semiconductor optical amplifiers are measured using the nonlinear optical loop mirror method and the principal state of polarization vector method. The polarization dependence of LEFs plays an important role in the nonlinear polarization rotation. The relationship between the polarization-dependence of LEFs and nonlinear polarization rotation in the Stokes space is demonstrated.
Optical Ring-Resonator Modulator Based on 0.8μm CMOS Technology
WANG Fan, QIU Chen, XIAO Si-Miao, HAO Yin-Lei, JIANG Xiao-Qing, WANG Ming-Hua, YANG Jian-Yi
Chin. Phys. Lett. 2009, 26 (10): 104206 .   DOI: 10.1088/0256-307X/26/10/104206
Abstract   PDF(pc) (1334KB) ( 879 )
Optical ring-resonator-based modulators are fabricated on the silicon-on-insulator material through the mature commercial 0.8μm complementary metal oxide semiconductor foundry. The device configuration is based on a single ring resonator coupled to one bus waveguide. The waveguide widths are about 1μm. The p-i-n junctions are employed to inject currents. The experimental result shows that the ring resonators with the quality factor of above 40000 are obtained. The maximum extinction ratio of the modulators is larger than 10dB. The speed is tens of nanoseconds, and the corresponding injected current is smaller than 10mA.
Measurement of Carrier-Envelope Phase and Field Strength of a Few-Cycle Pulse by Non-sequential Double Ionization
LI Hong-Yun, CHEN Jing, JIANG Hong-Bing, LIU Jie, FU Pan-Ming, GONG Qi-Huang, YAN Zong-Chao, WANG Bing-Bing
Chin. Phys. Lett. 2009, 26 (10): 104207 .   DOI: 10.1088/0256-307X/26/10/104207
Abstract   PDF(pc) (349KB) ( 550 )
We propose a method to measure the carrier-envelop phase (CEP) and the intensity of a few-cycle pulse by controlling the non-sequential double ionization (NSDI) process. By using an additional static electric field, we can change the momentum distribution of the double-charged ions parallel to the laser polarization from an asymmetrical double-hump structure to a nearly symmetrical one. It is found that the ratio between the strength of the static electric field and that of the laser field is sensitive to the CEP but robust against the intensity fluctuation. Therefore we can determine the CEP of a few-cycle pulse precisely by measuring the static electric field. Furthermore, if the CEP of the few-cycle pulse is fixed at a certain value, we can also calibrate the intensity of the laser pulse by the static electric field.
InP Based PD/EAM Integrated Photonic Switch
ZHANG Yun-Xiao, LIAO Zai-Yi, PAN Jiao-Qing, ZHOU Fan, ZHU Hong-Liang, ZHAO Ling-Juan, WANG Wei
Chin. Phys. Lett. 2009, 26 (10): 104208 .   DOI: 10.1088/0256-307X/26/10/104208
Abstract   PDF(pc) (1150KB) ( 637 )
A new compact three-port InP based PD/EAM (photo-detector/electro-absorption modulator) integrated photonic switch is reported. The device demonstrates bi-directional wavelength conversion over 20nm at 2.5Gbit/s with a low input optical power of about 20mW.
Existence of Shear Horizontal Surface Waves in a Magneto-Electro-Elastic Material
WEI Wei-Yi, LIU Jin-Xi, FANG Dai-Ning
Chin. Phys. Lett. 2009, 26 (10): 104301 .   DOI: 10.1088/0256-307X/26/10/104301
Abstract   PDF(pc) (203KB) ( 659 )
The existence of shear horizontal surface waves in a magneto-electro-elastic (MEE) half-space with hexagonal (6mm) symmetry is investigated. The surface of the MEE half-space is mechanically free, but subjected to four types of electromagnetic boundary conditions. These boundary conditions are electrically open/magnetically closed, electrically open/magnetically open, electrically closed/magnetically open and electrically closed/magnetically closed. It is shown that except for the electrically open/magnetically closed condition, the three other sets of electromagnetic boundary conditions allow the propagation of shear horizontal surface waves.
Analytic Solution for Magnetohydrodynamic Stagnation Point Flow towards a Stretching Sheet
DING Qi, ZHANG Hong-Qing
Chin. Phys. Lett. 2009, 26 (10): 104701 .   DOI: 10.1088/0256-307X/26/10/104701
Abstract   PDF(pc) (277KB) ( 825 )
A steady two-dimensional magnetohydrodynamic stagnation point flow towards a stretching sheet with variable surface temperature is investigated. The analytic solution is obtained by homotopy analysis method. The convergence region is computed and the feature of the solution is discussed.
PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
Beam Ion Transport from Neutron Emissivity Measurement in Deuterium Neutral Beam-Heated Deuterium Plasmas of the HL-2A Tokamak
ISOBE Mitsutaka, LIU Yi, YANG Jin-Wei, CHEN Wei, JI Xiao-Quan, YUAN Guo-Liang, ZHANG Yi-Po, ZOU Gui-Qing, LI Wei, LEI Guang-Jiu, DING Xuan-Tong, YAN Long-Wen, YANG Qing-Wei, DUAN Xu-Ru, OHDACHI Satoshi, MORITA Shigeru, TOI Kazuo
Chin. Phys. Lett. 2009, 26 (10): 105201 .   DOI: 10.1088/0256-307X/26/10/105201
Abstract   PDF(pc) (842KB) ( 796 )
An experiment at the HL-2A tokamak with a high-energy deuterium neutral beam (NB) injection (30keV, about 0.6MW) was performed. The emission of d-d fusion neutrons dominated by beam-plasmas reactions when the deuterium NB was injected into the deuterium target plasma was observed by means of a 235U fission chamber. To obtain information on NB deposition and the slowing down of beam ions in HL-2A plasmas, a very short-pulse deuterium NB injection, or the so-called ``blip'' injection, was performed into MHD-quiescent Ohmic deuterium plasmas. Analysis of neutron decay following the NB ``blip'' injection indicates that tangentially injected beam ions are well confined, slowing down classically in the HL-2A. In contrast to the MHD-quiescent plasma, anomalous losses of beam ions were observed when tearing mode instabilities were present.
Measurement of Plasma Density Produced in Dielectric Barrier Discharge for Active Aerodynamic Control with Interferometer
LI Gang, ZHANG Yi, XU Yan-Ji, LIN Bin, LI Yu-Tong, ZHU Jun-Qiang
Chin. Phys. Lett. 2009, 26 (10): 105202 .   DOI: 10.1088/0256-307X/26/10/105202
Abstract   PDF(pc) (2327KB) ( 1270 )
We utilize an interferometer to investigate the changes of the refractive index caused by dielectric barrier discharge plasma. The electronic density of the plasma produced is measured and analyzed tentatively. The results show that density of the plasma increases linearly with exciting voltages.
CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES
Pressure Effects on Solid State Phase Transformation of Aluminium Bronze in Cooling Process
WANG Hai-Yan, CHEN Yan, LIU Yu-Wen, LI Fei, LIU Jian-Hua, PENG Gui-Rong, WANG Wen-Kui
Chin. Phys. Lett. 2009, 26 (10): 106201 .   DOI: 10.1088/0256-307X/26/10/106201
Abstract   PDF(pc) (959KB) ( 1060 )
Effects of high pressure (6GPa) on the solid state phase transformation kinetic parameters of aluminum bronze during the cooling process are investigated, based on the measurement and calculation of its solid state phase transformation temperature, duration and activation energy and the observation of its microstructures. The results show that high pressure treatment can reduce the solid phase transformation temperature and activation energy in the cooling process and can shorten the phase transformation duration, which is favorable when forming fine-grained
aluminum bronze.
A Wide Band Strong Acoustic Absorption in a Locally Network Anechoic Coating
JIANG Heng, ZHANG Mi-Lin, WANG Yu-Ren, HU Yan-Ping, LAN Ding, WEIBing-Chen
Chin. Phys. Lett. 2009, 26 (10): 106202 .   DOI: 10.1088/0256-307X/26/10/106202
Abstract   PDF(pc) (1032KB) ( 533 )
Composite materials with interpenetrating network structures usually exhibit unexpected merit due to the cooperative interaction. Locally resonant phononic crystals (LRPC) exhibit excellent sound attenuation performance based on a periodical arrangement of sound wave scatters. Inspired by the interpenetrating network structure and the LRPC concept, we develop a locally network anechoic coating (LNAC) that can achieve a wide band of underwater strong acoustic absorption. The experimental results show that the LNAC possesses an excellent underwater acoustic absorbing capacity in a wide frequency range. Moreover, in order to investigate the impact of the interpenetrating network structure, we fabricate a faultage structure sample and the network is disconnected by hard polyurethane (PU). The experimental comparison between the LNAC and the faultage structure sample shows that the interpenetrating network structure of the LNAC plays an important role in achieving a wide band strong acoustic absorption.
Air Stability of Cs2CO3:Ag/Ag Cathode for Organic Light-Emitting Diodes
LIU Qian, DUAN Lian, ZHANG De-Qiang, QIAO Juan, WANG Li-Duo, QIU Yong
Chin. Phys. Lett. 2009, 26 (10): 106801 .   DOI: 10.1088/0256-307X/26/10/106801
Abstract   PDF(pc) (2120KB) ( 1401 )
We report the superior stability of the composite Cs2CO3:Ag/Ag cathode structure, which can be used in efficient organic light-emitting diodes (OLEDs). Devices with the Cs2CO3:Ag (1:10, 5nm)/Ag (95nm) cathode show a considerably improved lifetime compared with the control device with the Cs2CO3 (0.5nm)/Ag (100nm) cathode. The composite Cs2CO3:Ag/Ag film is proved to be stable in the atmosphere. X-ray diffraction (XRD) is applied to analyze the crystalline structure of the Cs2CO3:Ag film, and it is demonstrated that CsAg alloy is formed, leading to the improved stability of the thin film and the devices.
CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
First-Principles Study on the Half-Metallicity of Half-Heusler Alloys: XYZ (X=Mn, Ni; Y=Cr, Mn; Z=As, Sb)
LI Guan-Nan, JIN Ying-Jiu
Chin. Phys. Lett. 2009, 26 (10): 107101 .   DOI: 10.1088/0256-307X/26/10/107101
Abstract   PDF(pc) (281KB) ( 652 )
The electronic structures, magnetism, and half-metallicity of half-Heusler alloys XYZ (X=Mn, Ni; Y=Cr, Mn; Z=As, Sb) are investigated by means of the full-potential linearized augmented plane wave method within the generalized gradient approximation. We consider three types of atomic ordering (i.e., α, β, and γ phases for all of the alloys) and find that the α phase is energetically the most stable. From the calculated density of states and the total magnetic moments, we find that NiMnZ (Z=As, Sb) and NiCrAs are half-metallic ferromagnets, MnCrAs is a half-metallic antiferromagnet, and NiCrSb (MnCrSb) is almost a half-metallic ferromagnet (antiferromagnet).
Cu Doping Effect on Electrical Resistivity and Seebeck Coefficient of Perovskite-Type LaFeO3 Ceramics
WANG Hong-Chao, WANG Chun-Lei, ZHANG Jia-Liang, ZHAO Ming-Lei, LIU Jian, SU Wen-Bin, YIN Na, MEI Liang-Mo
Chin. Phys. Lett. 2009, 26 (10): 107301 .   DOI: 10.1088/0256-307X/26/10/107301
Abstract   PDF(pc) (418KB) ( 969 )
Perovskite-type LaFe1-xCuxO3 (x=0.10$, 0.14, 0.18) solid solution is prepared with the conventional solid-state reaction technique. The electrical resistivity and the Seebeck coefficient are measured in the temperature range 473-1073K to elucidate the Cu doping effect on the thermoelectric properties of the LaFeO3. The electrical resisitivity of LaFe1-xCuxO3 shows semiconducting behavior. The temperature dependence of the electrical resistivity indicates that the adiabatic small-polaron hopping mechanism is dominant for their electric transportations. The activation energy decreases with the increasing Cu content as well as the increasing temperature. The Seebeck coefficient changes from a negative value to a positive value around 510K, and increases with rising temperature up to 710K, then becomes saturated around 200μV/K. The Seebeck coefficient decreases with the substitution of Cu atoms in the temperature range of 573-1073K, while the electrical resistivity decreases with the substitution of Cu atoms in the whole measured temperature. Overall the power factor increases with rising temperature, and the highest value of power factor is 54μW/K2m for x=0.10 of Cu doping.
InGaN/GaN p-i-n Photodiodes Fabricated with Mg-Doped p-InGaN Layer
WANG Hui, ZHU Ji-Hong, JIANG De-Sheng, ZHU Jian-Jun, ZHAO De-Gang, LIU Zong-Shun, ZHANG Shu-Ming, YANG Hui,
Chin. Phys. Lett. 2009, 26 (10): 107302 .   DOI: 10.1088/0256-307X/26/10/107302
Abstract   PDF(pc) (416KB) ( 1316 )
Mg-doped p-InGaN layers with In composition of about 10% are grown by metalorganic chemical vapor deposition (MOCVD). The effect of the annealing temperature on the p-type behavior of Mg-doped InGaN is studied. It is found that the hole concentration in p-InGaN increases with a rising annealing temperature in the range of 600-850°C, while the hole mobility remains nearly unchanged until the annealing temperature increases up to 750°C, after which it decreases. On the basis of conductive p-type InGaN growth, the p-In0.1Ga0.9N/i-In0.1Ga0.9N/n-GaN junction structure is grown and fabricated into photodiodes. The spectral responsivity of the InGaN/GaN p-i-n photodiodes shows that the peak responsivity at zero bias is in the wavelength range 350-400nm.
Magnetoresistance in Parent Pnictide AFe2As2(A=Sr, Ba)
ZHENG Ping, CHEN Gen-Fu, LI Zheng, HU Wan-Zheng, DONG Jing, LI Gang, WANG Nan-Lin, LUO Jian-Lin
Chin. Phys. Lett. 2009, 26 (10): 107401 .   DOI: 10.1088/0256-307X/26/10/107401
Abstract   PDF(pc) (446KB) ( 567 )
Magnetoresistances of SrFe2As2 and BaFe2As2 in the magnetic ordered state are studied. Positive magnetoresistance is observed in the magnetic fields H applied in the azimuthes of θta = 0°and 30° with respect to the c-axis. The magnetoresistance can reach 20% for SrFe2As2 and 12% for BaFe2As2 at H = 9 T with θ= 0°(H || c). Above the magnetic transition temperature, the magnetoresistance becomes negligible. The data in the magnetic ordered state could be described by a modified two-band galvanomagnetic model including the enhancement effect of the applied magnetic field on the spin-density-wave gap. The field enhanced spin-density-wave gaps for different types of carriers are different. Temperature dependencies of the fitting parameters are discussed.
Exchange Bias in NiCo/FeMn Bilayers with Stripe Domains
LIN Jing, SHI Zhong, ZHOU Shi-Ming, ZHANG Xia, XIA Yun-Jie
Chin. Phys. Lett. 2009, 26 (10): 107501 .   DOI: 10.1088/0256-307X/26/10/107501
Abstract   PDF(pc) (304KB) ( 624 )
Exchange bias in NiCo/FeMn bilayers is established by alternating current (magnetic) field cooling, and stripe domains are induced as manifested by the ``double'' hysteresis loop. Only one resonance peak occurs at high magnetic fields in the in-plane ferromagnetic resonance spectra. The exchange field measured by both the magnetometry and ferromagnetic resonances is inversely proportional to the ferromagnetic layer thickness tFM. More remarkably, the exchange field determined by the ferromagnetic resonance is smaller than that of the magnetometry measurements. It is suggested to arise from the misalignment of the unidirectional anisotropic directions in neighboring domains.
Ferro-/Ferri-Exchange Coupled Magnetic Double Layers For High Density Magneto-optical Data Storage
WANG Xian-Ying, WANG Jing, YANG Jun-He
Chin. Phys. Lett. 2009, 26 (10): 107502 .   DOI: 10.1088/0256-307X/26/10/107502
Abstract   PDF(pc) (481KB) ( 579 )
PtCo/TbFeCo ferro-/ferri-exchange coupled double layer film (ECDL) was fabricated for high density magneto-optical (MO) data storage. At room temperature (RT), the PtCo film is in-plane magnetized and acts as a mask layer. However, at elevated temperature, it turns to be out-of-plane magnetized because of the strong exchange coupling interactions with the TbFeCo layer. Therefore, this ECDL film has a magnetically induced superresolution (MSR) effect. Combining it with the good Kerr signal at short wavelength, the PtCo/TbFeCo film can be a good candidate for blue laser-MSR MO data storage.
120° Ordered Phase of Triangular Lattice Antiferromagnetic Heisenberg Model with Long Range Couplings
DONG Zhan-Hai
Chin. Phys. Lett. 2009, 26 (10): 107503 .   DOI: 10.1088/0256-307X/26/10/107503
Abstract   PDF(pc) (192KB) ( 586 )
In order to look for the 120° order phase of triangular lattice Heisenberg antiferromagnet with long range couplings, the Hamiltonian is diagonalized with the Bogoliubov transformation within linear spin-wave approximation. It is found that when the long range spin couplings are taken into account, the transformation is valid only for certain regions in the spin coupling parameter space. These regions just correspond to the 120° (or Néel) ordered phase, which is very different from square lattice in terms of shape, size and topological property.
Magnetic Orderings and Néel Temperature of TbNi2B2C
LIU Zhao-Sen, Divis Martin, Sechovský, Vladimir
Chin. Phys. Lett. 2009, 26 (10): 107504 .   DOI: 10.1088/0256-307X/26/10/107504
Abstract   PDF(pc) (274KB) ( 331 )
We employ a two-ion model to calculate the spontaneous magnetization and susceptibility of TbNi2B2C with the mean-field theory, and derive an analytic formula for the Néel temperature of the material with the perturbation theory. In both the cases, only the four lowest crystal-electric-field (CEF) states are taken into account as base functions. Our theoretical results are consistent with the experimental data, manifesting the strong effects of the low lying CEF states on the magnetic behaviors of the material and the
suitability of the theoretical approach proposed here.
Effects of Interfacial Polarization on Voltage Tunability of Pb(Fe1/2Nb1/2)1-xTixO3 Single Crystals
LIU Kui, ZHANG Xin-Yi, XIAO Jing-Zhong,
Chin. Phys. Lett. 2009, 26 (10): 107701 .   DOI: 10.1088/0256-307X/26/10/107701
Abstract   PDF(pc) (432KB) ( 435 )
The voltage tunability of Pb(Fe1/2Nb1/2)1-xTixO3 single crystals is investigated at a low electric field (<130 V/cm) in a low frequency range (<1 MHz). The results show that the capacitance is strongly suppressed by the applied dc biases for both the rhombohedral sample and the tetragonal sample. A negative voltage tunability is only detected in the tetragonal sample. The origin of the giant tunability and the negative tunability is discussed based on the multipolarization-mechanism model and the equivalent circuit model, respectively. It is ascribed to the interfacial polarization at the interface of electrode/sample.
Photoluminescence of Charged Low-Density InAs/GaAs Quantum Dots
WANG Hai-Li, XIONG Yong-Hua, HUANG She-Song, NI Hai-Qiao, HE Zhen-Hong, DOU Xiu-Ming, NIU Zhi-Chuan
Chin. Phys. Lett. 2009, 26 (10): 107801 .   DOI: 10.1088/0256-307X/26/10/107801
Abstract   PDF(pc) (634KB) ( 512 )
We obtain low-density charged InAs quantum dots with an emission wavelength below 1μm using a low InAs growth rate. The quantum dots have a bimodal size distribution with an emission wavelength of around 1340nm and 1000nm, respectively. We observe the photoluminescence of the singly charged exciton in the modulation doped quantum dots in 77K.
Self-Assembled Colloidal Crystals in Capillary with Its Fiber Junction
YU Ping, OU Hong-Ye
Chin. Phys. Lett. 2009, 26 (10): 107802 .   DOI: 10.1088/0256-307X/26/10/107802
Abstract   PDF(pc) (1281KB) ( 585 )
Silica microspheres self-assembled in glass capillary are investigated. Monodisperse silica microsphere dispersions in diameter 320nm are self-organized into a bulk cylindrical colloidal crystal by evaporation induced nucleation and crystallization. The resulting colloidal crystals are characterized by optical microscopy and scanning electronic microscopy (SEM), and the SEM images show these crystals dominate in fcc lattice with its (111) crystallographic axis as longitudinal. The colloidal crystal filled capillary is packaged into a heat-shrink plastic tube and a fiber measurement system is designed to measure the optical property of colloidal bulk in capillary. It is found that an appreciable bandgap appears at wavelength 686nm from the transmission spectroscopy, which is consistent with the theoretical estimation. A considerable photonic band gap of up to -10 dB and a steep photonic band edge of up to 0.25dB/nm indicate that silica microspheres are promising for implementing optical filter applications in fiber systems.
Time-Resolved Photoluminescence of Metamorphic InGaAs Quantum Wells
MA Shan-Shan, WANG Bao-Rui, SUN Bao-Quan, WU Dong-Hai, NI Hai-Qiao, NIU Zhi-Chuan
Chin. Phys. Lett. 2009, 26 (10): 107803 .   DOI: 10.1088/0256-307X/26/10/107803
Abstract   PDF(pc) (672KB) ( 640 )
We investigate the temperature dependence of photoluminescence (PL) and time-resolved PL on the metamorphic InGaAs quantum wells (QWs) with an emission wavelength of 1.55μm at room temperature. Time-resolved PL measurements reveal that the optical properties can be partly improved by introducing antimony (Sb) as a surfactant during the sample growth. The temperature dependence of the radiative lifetime is measured, showing that for QWs grown with Sb assistance, the intrinsic exciton emission is dominated when the temperature is below 60K, while the nonradiative process becomes activated with further increases in temperature. However, without Sb assistance, the nonradiative centers are activated when the temperature is higher than 20K.
CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY
Depth Dependence of Tetragonal Distortion of a ZnO/Mg0.1Zn0.9O/ZnO Heterostructure Studied by Rutherford Backscattering/Channeling
WANG Kun, DING Zhi-Bo, LI Lin, YAO Shu-De
Chin. Phys. Lett. 2009, 26 (10): 108101 .   DOI: 10.1088/0256-307X/26/10/108101
Abstract   PDF(pc) (327KB) ( 597 )
Rutherford backscattering and channeling are used to characterize the structure of a ZnO/Mg0.1Zn0.9O/ZnO heterostructure grown on a sapphire (0001) substrate by rf plasma-assisted molecular beam epitaxy. The results show that the Mg0.1Zn0.9O layer has the same hexagonal wurtzite structure as the underlying ZnO layer, and the heterostructure has a good crystalline quality with χmin =5%, which is the ratio of the backscattering yields of aligned and random spectra in the near-surface region. Using the channeling angular scan around an off-normal <12-13> axis in the {101-0} plane of both ZnO and MgZnO layer, the tetragonal distortion eT, which is caused by the elastic strain in the epilayer, is determined. The depth dependence of eT is obtained by using this technique. It can clearly be seen that the elastic strain rapidly decreases with the increase in thickness of the ZnO film in the early growth stage and becomes slightly larger in the region of the Mg0.1Zn0.9O layer.
Memory Effect of Metal-Oxide-Silicon Capacitors with Self-Assembly Double-Layer Au Nanocrystals Embedded in Atomic-Layer-Deposited HfO2 Dielectric
HUANG Yue, GOU Hong-Yan, SUN Qing-Qing, DING Shi-Jin, ZHANG Wei, ZHANG Shi-Li,
Chin. Phys. Lett. 2009, 26 (10): 108102 .   DOI: 10.1088/0256-307X/26/10/108102
Abstract   PDF(pc) (618KB) ( 614 )
We report the chemical self-assembly growth of Au nanocrystals on atomic-layer-deposited HfO2 films aminosilanized by (3-Aminopropyl)-trimethoxysilane aforehand for memory applications. The resulting Au nanocrystals show a density of about 4×1011cm-2 and a diameter range of 5-8nm. The metal-oxide-silicon capacitor with double-layer Au nanocrystals embedded in HfO2 dielectric exhibits a large C-V hysteresis window of 11.9V for ± 11V gate voltage sweeps at 1MHz, a flat-band voltage shift of 1.5V after the electrical stress under 7V for 1ms, a leakage current density of 2.9×10-8 A/cm-2 at 9V and room temperature. Compared to single-layer Au nanocrystals, the double-layer Au nanocrystals increase the hysteresis window significantly, and the underlying mechanism is thus discussed.
Friction Properties of Bio-mimetic Nano-fibrillar Arrays
CHEN Shao-Hua, MI Chun-Hui
Chin. Phys. Lett. 2009, 26 (10): 108103 .   DOI: 10.1088/0256-307X/26/10/108103
Abstract   PDF(pc) (627KB) ( 434 )
Nano-fibrillar arrays are fabricated using polystyrene materials. The average diameter of each fiber is about 300nm. Experiments show that such a fibrillar surface possesses a relatively hydrophobic feature with a water contact angle of 142°. Nanoscale friction properties are mainly focused on. It is found that the friction force of polystyrene nano-fibrillar surfaces is obviously enhanced in contrast to polystyrene smooth surfaces. The apparent coefficient of friction increases with the applied load, but is independent of the scanning speed. An interesting observation is that the friction force increases almost linearly with the real contact area, which abides by the fundamental Bowden-Tabor law of nano-scale friction.
Mechanical Analogies of Fractional Elements
HU Kai-Xin, ZHU Ke-Qin
Chin. Phys. Lett. 2009, 26 (10): 108301 .   DOI: 10.1088/0256-307X/26/10/108301
Abstract   PDF(pc) (195KB) ( 988 )
A Ffactional element model describes a special kind of viscoelastic material. Its stress is proportional to the fractional-order derivative of strain. Physically the mechanical analogies of fractional elements can be represented by spring-dashpot fractal networks. We introduce a constitutive operator in the constitutive equations of viscoelastic materials. To derive constitutive operators for spring-dashpot fractal networks, we use Heaviside operational calculus, which provides explicit answers not otherwise obtainable simply. Then the series-parallel formulas for the constitutive operator are derived. Using these formulas, a constitutive equation of fractional element with 1/2-order derivative is obtained. Finally we find the way to derive the constitutive equations with other fractional-order derivatives and their mechanical analogies.
Improving Recording Density of All-Optical Magnetic Storage by Using High-Pass Angular Spectrum Filters
ZHUANG You-Yi, ZHANG Yao-Ju
Chin. Phys. Lett. 2009, 26 (10): 108501 .   DOI: 10.1088/0256-307X/26/10/108501
Abstract   PDF(pc) (244KB) ( 590 )
A new design is presented to improve the magnetic recording density in all-optical magnetic storage. By using the high numerical lens with a high-pass angular spectrum filter, circularly polarized laser pulses are focused into the magneto-optic film with the perpendicular anisotropy. Magnetization of the film is induced by the inverse Faraday effect. As the obstructed angle of the filter increases the magnetic recording density increases evidently. The magnetization intensity and the sidelobe effect are also discussed.
Evolutionary Prisoner's Dilemma Game Based on Division of Work
LI Zhi-Hua, WANG Bing-Hong, LIU Run-Ran, YANG Han-Xin
Chin. Phys. Lett. 2009, 26 (10): 108701 .   DOI: 10.1088/0256-307X/26/10/108701
Abstract   PDF(pc) (328KB) ( 645 )
We propose a new two-type-player prisoner's dilemma game based on the division of work on a square lattice, in which a fraction of the population μ are assigned type A and the rest B. In a one-shot two-player game, we let both of their original payoffs be scaled by a same multiplicative factor α>1, if two neighboring players are of different types; however we leave the payoffs unchanged if they are of the same type. Then we show that combined with the two-type setup, the square lattice can assist to induce different social ranks according to players' abilities to collect payoffs. Simulation results show that the density of cooperation is significantly promoted for a wide range of the temptation to defection parameters and that there are optimal values for both α and μ leading to the maximal cooperation level. We reach these results by analyzing the distribution of the players in the social ranks and we also show some typical snapshots of the system.
Properties of Traffic Risk Coefficient
TANG Tie-Qiao, HUANG Hai-Jun, SHANG Hua-Yan, XUE Yu
Chin. Phys. Lett. 2009, 26 (10): 108901 .   DOI: 10.1088/0256-307X/26/10/108901
Abstract   PDF(pc) (328KB) ( 744 )
We use the model with the consideration of the traffic interruption probability (Physica A 387(2008)6845) to study the relationship between the traffic risk coefficient and the traffic interruption probability. The analytical and numerical results show that the traffic interruption probability will reduce the traffic risk coefficient and that the reduction is related to the density, which shows that this model can improve traffic security.
GEOPHYSICS, ASTRONOMY, AND ASTROPHYSICS
Dispersion Relations for Isothermal Plasma around the Horizon of Reissner-Nordström-de Sitter Black Hole
M. Khayrul Hasan, M. Hossain Ali
Chin. Phys. Lett. 2009, 26 (10): 109501 .   DOI: 10.1088/0256-307X/26/10/109501
Abstract   PDF(pc) (249KB) ( 398 )
We formulate the general relativistic magnetohydrodynamic equations for isothermal plasma in spatially flat Reissner-Nordström-de Sitter metric by using 3+1 split of spacetime. Respective perturbed equations are linearized for rotating magnetized surroundings. These are then Fourier analyzed and the corresponding dispersion relations are obtained. These relations are discussed both analytically and numerically in order to investigate the nature of waves with positive angular frequency around the horizon.
Original Articles
Neutrino Lensing
LUO Xin-Lian
Chin. Phys. Lett. 2009, 26 (10): 109801 .   DOI: 10.1088/0256-307X/26/10/109801
Abstract   PDF(pc) (246KB) ( 585 )
Due to the intrinsic properties of neutrinos, the gravitational lens effect for a neutrino should be more colorful and meaningful than the normal lens effect of a photon. Other than the experiments operated at terrestrial laboratory, in principle, we can propose a completely new astrophysical method to determine not only the nature of the gravity of lens objects but also the mixing parameters of neutrinos by analyzing neutrino trajectories near the central objects. However, the angular, energy and time resolution of the neutrino telescopes are still comparatively poor, so we just concentrate on the two classical tests of general relativity, i.e. the angular deflection and the time delay of the neutrino by a lens object as a preparative work in this paper. In addition, some simple properties of neutrino lensing are investigated.
Quasi-Normal Modes of Gravitational Perturbation around a Reissner-Nordström Black Hole Surrounded by Quintessence
Mahamat Saleh, Bouetou Bouetou Thomas, , Timoleon Crepin Kofane,
Chin. Phys. Lett. 2009, 26 (10): 109802 .   DOI: 10.1088/0256-307X/26/10/109802
Abstract   PDF(pc) (226KB) ( 790 )
We investigate quasi-normal (QN) modes of gravitational perturbation around a Reissner-Nordström black hole surrounded by quintessence. The third-order Wentzel-Kramers-Brillouin approximation is used to evaluate QN frequencies. The behavior of the gravitational perturbation is plotted for some frequencies. Due to the presence of quintessence, QN modes of the Reissner-Nordström black hole damp at a slower rate.
A Dark Energy Model with Higher Derivative and Cosmological Evolution
ZHANG Xiao-Fei, LIU Hui-Hui
Chin. Phys. Lett. 2009, 26 (10): 109803 .   DOI: 10.1088/0256-307X/26/10/109803
Abstract   PDF(pc) (250KB) ( 474 )
We construct dark energy models which have high derivative terms. In the framework of a single scalar field model with a higher derivative, the equation of state (EOS) w might have some special character in the evolvement, which states that the universe will evolve in some interesting ways. We study the different kinds of dark energy models, and classify them into several genera by their character in the evolvement.
Locally Rotationally Symmetric Bianchi Type-I Model with Time Varying Λ Term
R. K. Tiwari, Navin Kumar Jha
Chin. Phys. Lett. 2009, 26 (10): 109804 .   DOI: 10.1088/0256-307X/26/10/109804
Abstract   PDF(pc) (303KB) ( 596 )
We investigate the locally rotationally symmetric (LRS) Bianchi type-I cosmological model for stiff matter and a vacuum solution with a cosmological term proportional to R-m (R is the scale factor and m is a positive constant). The cosmological term decreases with time. We obtain that for both the cases the present universe is accelerating with a large fraction of cosmological density in the form of a cosmological term.
COMMENTS AND ERRATA
Erratum: Experimental Study on Preparation Efficiency of Microstructured-Fiber Based Heralded Single-Photon Source at 1.5μm [Chin. Phys. Lett. 26(2009)034206]
ZHANG Si-Tuo, ZHANG Wei, ZHOU Qiang, HUANG Yi-Dong, PENG Jiang-De
Chin. Phys. Lett. 2009, 26 (10): 109901 .   DOI: 10.1088/0256-307X/26/10/109901
Abstract   PDF(pc) (183KB) ( 344 )
Erratum: Silver-Doping Induced Lattice Distortion in TiO2 Nanoparticles [Chin.Phys.Lett.26(2009)077809]
WU Xue-Wei, WU Da-Jian, LIU Xiao-Jun
Chin. Phys. Lett. 2009, 26 (10): 109902 .   DOI: 10.1088/0256-307X/26/10/109902
Abstract   PDF(pc) (135KB) ( 388 )
67 articles