We investigate the evolutionary prisoner's dilemma on a weighted scale-free network where the diversity of teaching ability is introduced to the network in the form of weight. Though the diversity of teaching ability is not a sufficient condition for the enhancement of cooperation, we find that the degree-dependent teaching ability plays an active role in the evolution of cooperation. A new phenomenon is found when the degree-dependent teaching ability is used: the distribution of the cooperator frequency displays a two-peak structure for a certain parameter range. We also investigate the effects of the degree-degree correlation of the network on the evolution of cooperation in the presence of the diversity of the teaching ability.

A simple scheme is presented for generating four-photon Greenberger-Horne-Zeilinger states with a large detuned interaction between a three-level atom and two bimodal cavities. In the proposed protocol, the quantum information is encoded on Fock states of the cavity-fields, and the atomic spontaneous emission can be effectively suppressed due to the fact that the excited state of the atom is adiabatically eliminated under the large detuning condition. The detection of the atom can collapse the cavity to the desired state. The experimental feasibility of our proposal is also discussed.

We propose a scheme to implement an unconventional geometric phase gate in circuit QED, i.e. two superconducting charge qubits inside a superconducting transmission line resonator. The quantum operation depends only on global geometric features, and thus is insensitive to the state of the cavity mode.

We discuss the dynamics of Bose-Einstein condensates in a double-well potential subject to decoherence (or particle loss). Starting from the full many-body dynamics described by the master equation, an effective Gross-Pitaevskii-like equation is derived in the mean-field approximation. By numerically solving the GP equation, we find that macroscopic quantum self-trapping disappears for strong decoherence, while generalized self-trapping occurs under weak decoherence. The fixed points have been calculated, and we find that an abrupt change from elliptic to an attractor and a repeller occurs, reflecting the metastable behavior of the system around these points.

We consider a model that contains two coupled superconducting charge qubits by sharing a large Josephson junction. We examine the dynamical properties of the linear entropy of two qubits and the probability of both qubits being in an excited state. The results show that the initial mean photon number, the initial phase of the field and the relative phase of the two qubits' levels play an important role in the evolution of the linear entropy of the two qubits and the probability.

It is well known that multiple superconducting charge qubits coupled to a transmission line resonator can be controlled to achieve quantum logic gates between two arbitrary qubits. We propose a scheme to realize a quantum conditional phase gate with a geometric property by circuit electrodynamics, and it is applied naturally to realize the quantum Fourier transform with high fidelity. It is also demonstrated that the application is feasible and considerable under the present experimental technology.

With realistic parameters, both analytical and computational studies demonstrate the feasibility of forming bright-bright vector solitons in a self-repulsive two-component Bose-Einstein condensate with attractive inter-component interaction. Moreover, the stability of such solitons is confirmed by direct numerical simulations, by a Bogoliubov spectrum analysis, and by examining the collisions between two vector solitons. Our results are of considerable experimental interest.

Exact solutions of the effective radial Schrödinger equation are obtained for some inverse potentials by using the point canonical transformation. The energy eigenvalues and the corresponding wave functions are calculated by using a set of mass distributions.

The effect of the local time-varying magnetic field in our G measurement with the time-of-swing method is studied by magnifying the magnetic field to cause a perceptible change in the pendulum's period. The experimental result shows that the coefficients of the change in the period to the magnetic field are 37(1) and 12(1) ms/gauss in the two horizontal directions respectively, which means that the systematic uncertainty due to the local magnetic field is less than 0.4 ppm in our G measurement.

We study the entropic force effects on black holes and photons. It is found that application of an entropic analysis restricts the radial change ΔR of a black hole of radius R_{H}, due to a test particle of a Schwarzschild radius R_{h} moving towards the black hole by Δx near a black body surface, to be given by a relation R_{H}ΔR= R_{h}Δx/2, or ΔR/λ_{M} =Δx/2λ_{m.} We suggest a new rule regarding entropy changes in different dimensions, ΔS= 2πkDΔl /λ, which unifies Verlinde's conjecture and the black hole entropy formula. We also propose the extension of the entropic force idea to massless particles such as photons. It is realized that there is an entropic force on a photon of energy Eγ, with F = G M (E_{γ}/c^{2)/R2,} and therefore the photon has an effective gravitational mass m_{γ}= E_{γ}/c^{2.}

We investigate the measure synchronization (MS) in two coupled bosonic Josephson junctions. By tuning up the coupling between the two dynamical systems, in addition to the normal MS, a nonlocal MS (NLMS) state is observed. Furthermore, with the dynamic stability analysis, we present the exact analytical solution of the transition point to NLMS.

We construct a two-soliton-like solution for the (2+1)-dimensional breaking soliton equation. The obtained solution contains two arbitrary functions and hence can model various cross soliton-like waves including the two-solitary waves. We show the evolution of some special cross soliton-like waves diagrammatically.

A chaotic firing pattern, characterized by non-smooth features and generated through the routine of intermittency from period 3, is observed in biological experiments on a neural firing pacemaker and reproduced in simulations by using a theoretical neuronal model with multiple time scales. This chaotic activity exhibits a scale law very similar to those of both the type-I intermittency generated in smooth systems and the type-V intermittency in non-smooth systems.

Unlike conventional chaotic systems, a memristor based chaotic circuit has an equilibrium set, whose stability is dependent on the initial state of the memristor. The initial state dependent dynamical behaviors of the memristor based chaotic circuit are investigated both theoretically and numerically.

A susceptor structure with a ring channel for a vertical metalorganic chemical vapor deposition reactor by induction heating is proposed. Thus the directions of heat conduction are changed by the channel, and the channel makes the heat in the susceptor redistribute. The pattern of heat transfer in this susceptor is also analyzed. In addition, the location and size of the channel in the susceptor are optimized using the finite element method. A comparison between the optimized and the conventional susceptor shows that the optimized susceptor not only enhances the heating efficiency but also the uniformity of temperature distribution in the wafer, which contributes to improving the quality of the film growth.

A pixel array CdZnTe imaging system, employing a 40×40×5 mm^{3} pixellated CdZnTe detector, is established. The imaging polarization effect in the CdZnTe pixellated detector for a collimated Cs^{137} Gamma source is investigated in detail. The experimental results for different irradiated fluxes indicate that excessive irradiated flux indeed causes central pixels to be shut off completely. The imaging performance of the polarized detector is severely degraded. Polarized detector counts are simultaneously reduced to one-third of the non-polarized detector counts. A theoretical model of potential distribution is also proposed by solving the Poisson equation and, in turn, the electric potential distortion for high irradiated flux is discussed by comparison with the experimental results.

We propose a new mass matrix ansatz: At the grand unified (GU) scale, the standard model (SM) Yukawa coupling matrix elements are integer powers of the square root of the GU gauge coupling constant ε≡√αGU , multiplied by order unity random complex numbers. It relates the hierarchy of the SM fermion masses and quark mixings to the gauge coupling constants, greatly reducing the SM parameters, and can give good fitting results of the SM fermion mass, quark mixing and CP violation parameters. This is a neat but very effective ansatz.

We give a brief discussion on the measurement of the cross section for DD production around the ψ(3770) resonance, and point out a new calculation of the cross sections based on the absolute measurements. Compared with single tag and double tag analyses, the new calculation provides us with many more opportunities to perform the cross section measurement.

Half-lives of the proton radioactivity for spherical proton emitters are investigated theoretically in the Wentzel-Kramers-Brillouin approximation. Microscopic proton-nucleus interaction potentials are obtained by folding the densities of the residual daughter nuclei with renormalized M3Y effective interactions. We also take the spectroscopic factor (S_{p}) into account in the calculation, which is evaluated in the relativistic mean field approach using the force NL3. The calculated results are found to be in good agreement with the experimental data.

DING Huai-Bo, ZHU Sheng-Jiang, WANG Jian-Guo, GU Long, XU Qiang, XIAO Zhi-Gang, YEOHA Eing-Yee, ZHANG Ming, ZHU Li-Hua, WU Xiao-Guang, LIU Ying, HE Chuang-Ye, WANG Lie-Lin, PAN Bo, LI Guang-Sheng

Chin. Phys. Lett. 2010, 27 (7):
072501
.
DOI: 10.1088/0256-307X/27/7/072501

High spin states in odd-odd ^{98}Tc nuclei are studied by in-beam γ-ray spectroscopy with the ^{96}Zr(^{6}Li, 4n) fusion-evaporation reaction at a beam energy of 35 MeV. The previous level scheme is updated. A band based on 1090.7 keV is expanded, and another band based on 1920.6 keV is newly identified. The observed two negative parity bands in ^{98}Tc are proposed to be a pair of chiral doublet bands with the configuration πg_{9/2} νh_{11/2}. The evidence supporting the assignment of the chiral doublet bands is discussed. Signature splitting and signature inversion are observed in the πg_{9/2}ν h_{11/2} band in ^{98}Tc.

We study the pseudo-rapidity distribution of hadron multiplicities of high energy Pb+Pb collisions by using color glass condensate dynamics at LHC/ALICE in the fixed coupling case. It is found that after including the pomeron loop effects the charged hadron multiplicities at central rapidity are about 1500 for central Pb+Pb collisions, which are significantly smaller than the saturation based calculations,~1700÷2500 and compatible with that based on a study of multiplicities in the fragmentation region.

The electronic structure and geometric distribution of phosphor replaced by sulfur in potassium dihydrogen phosphate (KDP) are investigated by first-principles calculations. The point defect narrows down the energy gap to about 4.9 eV, corresponding to a two-photon absorption of 355 nm after correction. This can explain the decrease of the laser damage resistance in KDP crystals. Moreover, the defects twist the crystal structure and weaken bonds, especially the O-H bonds, so these bonds may be the first sites to crack under laser irradiation.

We present a comparison between intracavity cooling and external cavity cooling for optical refrigeration. The results show that the intracavity scheme is preferred at low optical densities (<0.008), while the external cavity scheme is preferred at higher optical densities (>0.01). We can choose the proper scheme for different cases in experiments. Moreover, under the same conditions, taking Yb^{3+}-doped ZBLAN (ZrF_{4}-BaF_{2}-LaF_{3}-AlF_{3}-NaF) film as an example, the cooling processes of the two scheme are obtained. The calculated results show that intracavity cooling will achieve a larger temperature drop for a thin film sample. Finally, the diode laser may become a candidate for the intracavity model briefly discussed.

Employing the two-state model and the time-dependent wave packet method, the influence of femtosecond laser wavelength on the evolution of the double-minimum electronic excited state wave packet is numerically investigated. For different laser wavelengths, evolutions of the double-minimum electronic excited state wave packet with time and internuclear distance are different. One can control the evolution of the wave packet by varying the laser wavelength appropriately, which will benefit the light manipulation of atomic and molecular processes. Furthermore, study of the dynamics of the NaRb molecule may yield clues to creating an ultracold molecule.

A K-N_{2} mixture is irradiated in a glass fluorescence cell with pulses of 710 nm radiation from an OPO laser, populated K_{2} (^{1Λ}_{g)}^{ }state by two-photon absorption. The cross section for ^{1Λ}_{g} →^{3Λ}_{g} transfer in K_{2} is determined using molecular fluorescence spectrometry. The cell temperature is kept constant at 553 K. The N_{2} pressure is varied between 40 Pa and 400 Pa. The effects of K_{2}-K collisions could not be neglected. These effects are subtracted out by using the results of the pure K experiment. The cross sections are (3.8±1.5)×10^{-15} cm^{2} for K_{2} (^{1Λ}_{g)+}N_{2} → K_{2} (^{3Λ}_{g)+}N_{2} and (8.9± 3.5)×10^{-15}cm^{2} for K_{2} (^{3Λ}_{g)} collisions with N_{2}.

The stabilization ratios R for double-electron transfer, i.e., the cross section ratios of true double capture to total double-electron transfer, are measured in O^{6+}+He, Ne and Ar collisions at 6 keV/u. A high R value about 68% is obtained for the He target, while for the Ar target, the R value is only 8%. The high R value for the He target is due to the significant direct population of the (2l, nl') configurations with high n. For the Ar target, the (quasi)symmetric configurations (3l, nl') lead to the much lower R value. Neglecting the core effects, the O^{6+} ion can be taken as a bare ion C^{6+} except the occupied 1s shell, and then the measured R values are compared with previous experimental results of C^{6+} projectile ions at similar impact velocity. It yields good agreement with the Ne and Ar target, while the occupied 1s shell for the O^{6+}+He system results in a higher R value than that in C^{6+}+He collisions.

With our newly developed method, we calculate the spin-orbit splitting states 5e_{1/2} and 5e_{3/2} of the CF_{3}I molecule incorporating the relativistic effects. Our theoretical results agree excellently with the recent experimental observations. The present study shows that relativistic effects can evidently change the electron momentum distributions of molecular orbitals when a medium Z element is included, such as iodine.

FUNDAMENTAL AREAS OF PHENOMENOLOGY(INCLUDING APPLICATIONS)

The third-order nonlinear optical properties of a series of polythiophenes are investigated with the Z-scan method under picosecond pulse laser irradiation at 532 nm. The copolymers exhibit a good nonlinear response: large nonlinear refraction coefficients without nonlinear absorption. The signs of nonlinear refraction coefficients are positive, which are opposite to the negative signs of the polythiophene reported before. The mechanism accounting for the process of nonlinear refraction under pulse laser excitation is analyzed from the viewpoint of the electron-donor/acceptor units of polythiophenes. Moreover, changes of nonlinearity according to the lengths of main chains in polythiophene molecules are discussed.

We propose a new application of the optical adiabatic passage effect for the excitation of a thermal atomic beam, which will be used in the calcium active optical clock to produce population inversion. A comparison between the optical adiabatic passage effect and the Rabi π pulse is investigated, 99% of the calcium atoms in the atomic beam that has a wide velocity distribution will be excited to the upper state for population inversion using the adiabatic passage, while 76% at most will be excited to the excited state using the π pulse with suitable parameters.

The critical phenomena of a Brillouin laser are analyzed theoretically. The results show that the behavior of a Brillouin laser in the threshold region is a second-order phase transition. The critical point of the phase transition is the gain threshold of the Brillouin laser, and the order parameter is the amplitude of the Stokes component in stimulated Brillouin scattering. The critical slow-down phenomenon and the typical characteristics in phase transition are demonstrated. Further work on the combination of nonlinear optics and phase transition in the Brillouin laser may lead to a new view and findings that could be significant for both fields.

We propose a scheme of optical one-way transmission by using one-dimensional photonic crystals (PhCs) with diffraction gratings on one side. The one-way transmission is realized by making the PhC opaque to the zeroth diffraction order and transparent to another propagating (in air) diffraction order. For such a structure with 10-period PhC, 93% of the incident energy passes through when an electromagnetic wave impinges from one side, and the transmittance decreases to the order of 0.001% as the electromagnetic wave illuminates from the other side.

Three-dimensional SiO_{2} photonic crystals (PhCs) are fabricated on quartz substrates by the vertical deposition method. Scanning electron microscopy measurement reveals that the samples exhibit an ordered close-packed arrangement of SiO_{2} spheres. It is found that the position of the [111] photonic band gap (PBG) shifts to a long wavelength (red shift) with increasing sphere size. Gap broadening effects are observed due to the presence of defects in the samples. Moreover, the optical properties of the PBG are very sensitive to the annealing temperature. Our results indicate that the optical properties of the PBG can be easily tuned in the visible region by appropriate experimental parameters, which will be useful for practical applications of PhC optical devices.

According to the interference theory of double-grating interferometers, the feature of Moiréfringe imaging in each region is investigated and a novel micro-displacement measuring method based on optical path modulation is proposed. The basic measurement principle is that the displacement is measured through Moiréfringe shifting, which is caused by the whole phased object thickness variation, in the case of non-relative movement of gratings. The object displacement measured can be changed into the phased object variation inserted in region Ⅱ using a mechanical arrangement. The principle of the micro-displacement measurement is analyzed theoretically. The light intensity of the distributing image in each interference region is given no matter whether we insert the phased object or not. The effect on the Moiré fringe of the whole thickness variation of the phased object is also discussed. It is confirmed that the Moiré fringe shifts with phased object variation by calculation with MATLAB. The experimental result proves that the resolution of this method is 2.1093 μm, and the resolution of the system is 0.5273 μm after a four-subdivision circuit.

A novel tunable microwave photonic filter based on a microfiber ring resonator is proposed and experimentally demonstrated. A fiber ring laser based on the microfiber ring resonator is employed to generate two single-longitudinal-mode carriers, then the dispersive element introduces the delay between two modulated carriers. By adjusting the diameter of the microfiber ring resonator, the proposed microwave photonic notch filter can be continuously and widely tuned. The measured notch rejection ratio is greater than 35 dB, and there is good agreement between the experimental result and the theoretical analysis.

We report stable narrow linewidth laser systems based on self-developed Littman configuration external cavity diode lasers (ECDLs). The frequency of the ECDL is stabilized to a high fineness ultralow-expansion glass reference cavity with the Pound-Drever-Hall technique. By heterodyne beating of two identical systems, we conclude that the linewidth of each ECDL is reduced to lower than 150 Hz and its frequency stability reaches 4.3× 10^{-14} at an averaging time of 1 s, the averaged long-term frequency drift is less than 0.2 Hz/s over 30 h measurement time.

A kind of high birefringence SF6 soft glass photonic crystal fiber (HBSF6-PCF) is proposed. The properties of birefringence, dispersion, nonlinear coefficient and the transmission characteristics are studied by the multipole method and the adaptive split-step Fourier method. The numerical results show that the birefringence and the nonlinear coefficient reach the orders of 10^{-2} and 10^{-1}, respectively. In addition, the HBSF6-PCFs can generate very smooth supercontinuum spectra when illuminated with femtosecond pulsed light of 1064 nm. It is found that up to 800 nm spectral width (evaluated at -5 dB from the peak) is achieved. Therefore, the advantage of the HBSF6-PCFs is such that a high birefringence, a high nonlinearity and a smooth supercontinuum are perfectly combined in them.

The Goos-Hänchen displacement of a light beam transmitting through an indefinite metamaterial slab is studied. The results indicate that the displacement would be negative or positive for different parameters, and the necessary conditions for negative or positive displacements are summarized. Due to the special anisotropic properties, the directions of displacements for different polarization beams are opposite by proper design. In addition, the simultaneously enhanced positive and negative displacements will appear at different resonant angles under consideration of the active slab. These phenomena could have convenient applications in optical devices.

We present the dispersion relation of guided-mode resonances in planar periodic waveguides, both for s-polarized (TE mode) and p-polarized (TM mode) incident waves. For a fixed homogeneous planar waveguide, dispersion curves of the TE eigenmode cannot cross that of the TM eigenmode at all. That is to say, at a certain wavelength, TE and TM modes cannot be excited with the same propagation constant. Due to Bragg reflection in the planar periodic waveguide, dispersion curves of the TE leaky mode may intersect with that of the TM leaky mode in the first Brillouin zone. We employ these intersections to achieve polarization-independent guided-mode resonance filters.

We report observations of the enhancement and suppression of four-wave mixing (FWM) in an electromagnetically induced transparency window in a Y-type ^{85}Rb atomic system. The results show the evolution of the dressed effects (from pure enhancement to partial enhancement/suppression, and finally into pure suppression) in the degenerate-FWM processes. Moreover, we use the perturbation chain method to describe the FWM process. Finally, we observe the polarization dependence of the enhancement and suppression of the FWM signal.

We demonstrate a high-efficiency continuous-wave Tm:YAG ceramic laser pumped with a Ti:sapphire laser. An output power up to 860 mW is obtained under an absorbed pump power of 2.21 W at 785 nm, corresponding to a slope efficiency of 42.1% and optical to optical efficiency of 22%. The measured central wavelength is 2012 nm.

A diode laser (LD) clad-pumped narrow linewidth all-fiber Tm^{3+}-doped fiber laser is reported with a maximal output power of 27 W at 1.947μm. By successively splicing an LD pigtail fiber, a single-mode Tm^{3+}-doped fiber, and a multi-mode Tm^{3+}-doped fiber, the fiber laser has 70 pm narrow linewidth output, and a high slope efficiency of nearly 47.5% with respect to the launched pump power. The high reflectivity fiber Bragg gratings, which are directly written into the single-mode Tm^{3+}-doped fiber core by the 800 nm femtosecond pulsed laser, act as the high reflectivity coupler. The output laser has diffraction-limited beam quality with a factor M^{2} of 1.29, when the output laser power is nearly 27 W.

Ta_{2}O_{5}/SiO_{2} and ZrO_{2}/SiO_{2} high reflecting (HR) coatings are prepared by ion beam sputtering and electron beam evaporation, respectively. The laser-induced damage thresholds (LIDTs) of these samples are investigated with 2 μm femtosecond pulse lasers (80 fs, 1 kHz). It is found that the Ta_{2}O_{5}/SiO_{2} HR coating has a higher capability of laser damage resistance than the ZrO_{2}/SiO_{2} HR coating in the 2 μm femtosecond regime. The scanning electron microscope results show that the damage sites of the ZrO_{2}/SiO_{2} HR coating have a relatively porous structure, the loose structure of coatings will provide more sites for water molecules, and the LIDTs of HR coatings will be reduced as a result of the strong water absorption at the wavelength of 2 μm.

A multilayered configuration broad bandwidth polarization insensitive reflector realized by a multi-subpart profile grating structure is presented. The properties of the reflector are investigated by rigorous coupled-wave analysis. It is shown that over a broadband spectrum of 1.62-1.76 μm, the reflector demonstrates high reflectivity (R>99%), low polarization-dependent loss (PDL<0.02 dB) and good angular insensitivity of about 29.6° for both transverse electric and transverse magnetic polarized waves.

The influence of the nonlinearity of electrodynamic loudspeakers on the performance of thermoacoustic refrigerators with the loudspeakers as acoustic sources is studied by nonlinear equivalent circuit models of electrodynamic loudspeakers driven by current and voltage. The simulated results demonstrate that there are different nonlinear effects between current-drive and voltage-drive refrigerators, and the differences are mainly induced by the motional electromotive force caused by the coil moving in the magnetic field. With voltage driving, the influence of the nonlinearity of the loudspeaker on the diaphragm displacement and acoustic output power is much smaller than that with current driving. Therefore, considering the nonlinearity of the loudspeakers, a proper driving method must be chosen according to the practical applications although little difference is found with the linear models.

A new kind of non-contact linear actuator (motor) driven by surface acoustic waves (SAWs) is presented, in which the stators are made from SAW delay lines using 128° YX-LiNbO_{3} substrates. A fluid layer is introduced between the slider and the stator of the actuator, and the slider is a circular aluminum disk suspended on the surface of the liquid (water) layer. As the SAW is excited on the stator, the SAW is converted to a leaky wave in the interface of the stator and the liquid, and then propagates into the liquid. Owing to the nonlinear effect of wave propagation, acoustic streaming is generated, which pushes the slider to move. By the experiments, the relations between the slider velocity and the experimental parameters, such as the exciting voltage of the SAWs, the thickness and the kinematic viscosity of the liquid layer, are obtained.

It is well known that Lamb waves in a plate with a mirror plane can be separated into two uncoupled sets: symmetric and anti-symmetric modes. Based on this property, we present a revised plane wave expansion method (PWE) to calculate the band structure of a phononic crystal (PC) plate with a mirror plane. The developed PWE method can be used to calculate the band structure of symmetric and anti-symmetric modes separately, by which the depending relationship between the partial acoustic band gap (PABG), which belongs to the symmetric and anti-symmetric modes alternatively, and the position of the scatterers can be determined. As an example of its application, the band structure of the Lamb modes in a two-dimensional PC plate with two layers of void circular inclusions is investigated. The results show that the band structure for the symmetric and anti-symmetric modes can be changed by the position of the scatterers drastically, and larger PABGs will be opened when the scatterers are inserted into the area of the plate, where the elastic potential energy is concentrated.

We discuss the intrinsic concordance between the wide scattering feature of density-flow plot and the empirical spacing distributions for traffic flows. It is shown that by choosing a proper threshold parameter, the boundaries of truncated spacing distributions could well determine the envelope of the 2D region of synchronized flow.

We investigate the Hopf bifurcations of the recently proposed smooth-and-discontinuous (SD) oscillator which exhibits both smooth and discontinuous dynamics depending on the value of a parameter α. The nonlinearity presented in this system characterizes irrationality and piecewise linearity for smooth and discontinuous cases, respectively, which could not meet the requirements of the conventional methods due to the barrier of Taylor expansion. Introducing a series of new kinds of elliptic integrals of the first and second kind to the perturbed oscillator, we obtain the Poincare-Birchoff normal forms of Hopf bifurcations for both smooth and discontinuous regimes. We also demonstrate the criteria for the occurrence of Hopf bifurcations, the stability of periodic solutions bifurcating from the equilibria and the excellent agreement between the theoretical and numerical results.

A nonlinear flow mathematical model is established and the grid equation is deduced. A nonlinear flow reservoir numerical simulation program is compiled. The permeability loss coefficient is used to describe the permeability loss. A pilot calculation is made on the basis of actual field data, which reflects the reservoir development characteristics. The numerical simulation program based on nonlinear flow can anticipate the dynamic characteristics of the ultra-low permeability reservoir exploitation more exactly.

PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES

A particle-in-cell simulation is developed to study dc plasma immersion ion implantation. Particular attention is paid to the influence of the voltage applied to the target on the ion path, and the ion flux distribution on the target surface. It is found that the potential near the aperture within the plasma region is not the plasma potential, and is impacted by the voltage applied to the implanted target. A curved equipotential contour expands into the plasma region through the aperture and the extent of the expansion depends on the voltage. Ions accelerated by the electric field in the sheath form a beam shape and a flux distribution on the target surface, which are strongly dependent on the applied voltage. The results of the simulations demonstrate the formation mechanism of the grid-shadow effect, which is in agreement with the result observed experimentally.

CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES

We investigate the influence of Fe contamination on the minority carrier lifetimes of multi-crystalline silicon. The minority carrier lifetime is measured by the microwave photoconductive decay method. The original bulk lifetime is about 30 μs after passivation with iodine solution. After intentional Fe contamination, the bulk lifetime declines with increasing temperature. Fast cooling in air conduces to the formation of more interstitial Fe ([Fe]_{i}). Slow cooling through the control of the furnace temperature limits the formation of more [Fe]_{i}, but leads to the formation of precipitation. The data support the idea that the minority carrier lifetime in multi-crystalline silicon mainly depends on the distribution of Fe but not the total amount. A favorite effect of [Fe]_{i} gettering is discovered after conventional phosphorus diffusion, and the [Fe]_{i} concentration remaining in the silicon wafer is acceptable for solar cell applications.

LiNi_{1-y}Co_{y}O_{2}(0.1_{≤} y_{≤}0.4) positive electrode materials are synthesized by a chemical method with stoichiometric acetates of related cations. Their crystal structure, stoichiometry and electrochemical behaviors versus Co concentration are investigated by x-ray diffraction, synchrotron-based x-ray absorption fine structure and galvanostatic cycling measurements. The results reveal that the non-stoichiometric Ni^{2+}, Li/Ni cation mixing and polarization are reduced as the amount of Co substitution increases, clearly indicating that the Co element is a medium for easily oxidizing Ni^{2+} to Ni^{3+} during the synthesis process.

The effects of rare earth addition on the glass forming ability of Fe_{50-x}Cr_{15}Mo_{14}C_{15}B_{6}M_{x} (x=0, 2 and M=Y, Gd) bulks and ribbons are studied. The thermal and structural properties of the samples are measured by a combination of differential scanning calorimetry (DSC), x-ray diffraction and scanning electron microscopy. Chemical compositions are checked by energy dispersive spectroscopy analysis. The copper mold casting technique leads to a fully amorphous structure up to 2 mm only for compositions containing Y or Gd. In the case of ribbons, a fully amorphous phase is observed for all the compositions. The roles of Y and Gd are discussed on the basis of melting behavior analyzed by high-temperature DSC. Such elements act as oxygen scavengers, avoiding heterogeneous nucleation.

Design of superhard bulk materials requires predicting their hardness, challenging current theories for material design. By introducing a concept of condensing force (CF), it is shown via initio calculations for fcc (Ni, Cu, Al, Ir, Rh, Au, Ag, Pd) and hcp Re crystals that materials with larger CF can have greater hardness. Since the calculation of CF is easy, this method might prove a convenient way to evaluate the hardness of newly designed materials.

The transition process to film pool boiling in microgravity is studied experimentally aboard the Chinese recoverable satellite SJ-8. A quasi-steady heating method is adopted, in which the heating voltage is controlled to increase exponentially with time. Small, primary bubbles are formed and slid on the surface, which coalesce with each other to form a large coalesced bubble. Two ways are observed for the transition from nucleate to film boiling at different subcoolings. At high subcooling, the coalesced bubble with a smooth surface grows slowly. It is then difficult for the coalesced bubble to cover the whole heater surface, resulting in a special region of transition boiling in which nucleate boiling and local dry areas can coexist. In contrast, strong oscillation of the coalesced bubble surface at low subcooling may cause rewetting of local dry areas and activation of more nucleate sites, resulting in an abrupt transition to film boiling.

We employ the second renormalization group method of tensor-network states to investigate thermodynamic properties of the ferromagnetic and antiferromagnetic Potts model on triangular lattices. From the temperature dependence of the internal energy and the specific heat, both the critical temperatures and critical exponents are evaluated. For the q=3 antiferromagnetic Potts model, the critical temperature is found to be T_{c} = 0.627163 ±0.000003, which is at least one order of magnitude more accurate than that obtained by other methods.

A category of non-axisymmetric oscillations of acoustically levitated water drops was observed. These oscillations can be qualitatively described by superposing a sectorial oscillating term upon the initial oblate shape resulting from the effect of acoustic radiation pressure. The oscillation frequencies are around 25 Hz for the 2-lobed mode and exactly 50 Hz for the 3- and 4-lobed modes. These oscillations were excited by the disturbance from the power supply. For the same water drop, higher mode oscillations were observed with more oblate initial shape, indicating that the eigenfrequencies of these non-axisymmetric oscillations decrease with increasing initial distortion. The maximum velocity and acceleration within the oscillating drop can attain 0.3 m·s^{-1} and 98.7 m·s^{-2} respectively, resulting in strong fluid convection and enhanced heat and mass transfer.

Up to now, measured results of the contact angle on rough surfaces have been explained usually based on the Wenzel equation (1936) and the Cassie-Baxter equation (1944). However, these equations do not take into account considerations of liquid wetting behaviors on rough surfaces, and this leads to poor understanding of the mechanisms of contact between liquid droplets and rough surfaces (e.g. contact angle hysteresis). We propose a new model for the contact angle of liquid droplets. By means of the present model, we can well understand the experimental data which could not be well explained by the Wenzel equation and the Cassie-Baxter equation.

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

We investigate the strain effects on the electronic properties of boron nitride nanoribbons (BNNRs) by using first-principles calculations. The results show that the energy gap of BNNRs with both armchair edges (A-BNNRs) and zigzag edges (Z-BNNRs) decreases as the strain increases. As strain increases, the energy gaps of Z-BNNRs decrease rapidly as the width increases and reduce significantly to small values, which makes Z-BNNRs change from wide-gap to narrow-gap semiconductors.

Deep-trap properties of high-dielectric-constant (k) HfO_{2} thin films are investigated by deep-level transient spectroscopy and capacitance-voltage methods. The hole traps of the HfO_{2} dielectric deposited on a p-type Si substrate by sputtering are investigated in a metal-oxide-semiconductor structure over a temperature range of 300-500 K. The potential depth, cross section and concentration of hole traps are estimated to be about 2.5 eV, 1.8× 10^{-16} cm^{2} and 1.0× 10^{16} cm^{-3}, respectively.

Ag/Cu-doped titania nanotubes (Ag/TiNT, Cu/TiNT) are prepared by a metal vapor vacuum arc implanter. A scanning electronic microscope is employed for microstructural characterization. The photo-current performance of doped titania nanotubes under UV and visible light is tested by an electrochemical workstation CS300UA, the results show that the absorption edge of both Ag/TiNT and Cu/TiNT samples shifts to the visible light region and the band gap becomes narrower. Ag/TiNT possesses better photo-current ability than Cu/TiNT under UV and visible light. Titania doped with Ag and Cu metal ions is also studied based on the linearized augmented plane-wave method implemented by WIEN2k package, the result becomes better with the experimental performance.

We perform a first-principles calculation based on density functional theory to investigate the interface between single layer graphene and metal oxides. Our study reveals that the monolayer graphene becomes semiconducting by single crystal SiO_{2} and Al_{2}O_{3} contact, with energy gaps to ~0.9 and ~1.8 eV, respectively. We find the gap originates from the breakage of π bond integrity, whose extent is related to the interface atom configuration. We believe that our results highlight a promising direction for the feasibility to apply large scale graphene layers as building blocks in future electronics devices.

In the light of the decomposition of the SU(2) gauge potential for I=1/2, we obtain the SU(2) Chern-Simons current over S^{4,} i.e. the vortex current in the effective field for the four-dimensional quantum Hall effect. Similar to the vortex excitations in the two-dimensional quantum Hall effect (2D FQH) which are generated from the zero points of the complex scalar field, in the 4D FQH, we show that the SU(2) Chern-Simons vortices are generated from the zero points of the two-component wave functions Ψ, and their topological charges are quantized in terms of the Hopf indices and Brouwer degrees of Φ-mapping under the condition that the zero points of field Ψ are regular points.

The energy levels of holes in a p-type δ-doped GaAs structure under a magnetic field are theoretically calculated within the framework of the effective mass approximation for a uniform acceptor distribution. The electronic structure is calculated by solving the Schrödinger and Poisson equations self-consistently. The effect of the magnetic field on the potential profile changes the degree of the confinement and localization, and thus this behavior can be used to study these systems in regions of interest, without the need to grow many different samples. It is found that the heavy-hole subbands contain many more energy states than the light-hole ones; the population of the heavy-hole levels represents approximately 91% of all the carriers without magnetic field. With increasing magnetic field the total population of the heavy-holes increases and the number of filled states changes.

A simulation on the electric field distribution near the electrode is proposed to explain the reason for using nanosized carbon black mixed with ethylene vinyl acetate, as the electrode could lead to more charge injection into the polymer than using a deposited metal electrode. The electrode is simplified to a layer of conductive semi-spheres with fixed size and constant electric potential. By using the finite element method, it is found that both the size of the semi-spheres and the distance between adjacent semi-spheres could dramatically influence the electric field near the surface of the spheres; these are considered to be the two decisive factors for the charge injecting rate at electrodes of various materials.

Using density functional theory, we study high hydrogenated zigzag single-walled carbon nanotubes from (7,0) to (11,0). Two structure transitions are classified: type A is a metallic transition and type B is a "semiconductive transition'' according to the energy band structure. The charge density transforms only at the C-C bonds without hydrogenated sites. The sp^{3} hybridization is mainly enhanced for all the C-C bonds in the vertical axial direction for type-A configurations, and the sp^{3} hybridization mainly increases for all C-C bonds along the axial direction for the type-B case.

InAs/GaSb superlattice (SL) midwave infrared photovoltaic detectors are grown by molecular beam epitaxy on GaSb(001) residual p-type substrates. A thick GaSb layer is grown under the optimized growth condition as a buffer layer. The detectors containing a 320-period 8ML/8ML InAs/GaSb SL active layer are fabricated with a series pixel area using anode sulfide passivation. Corresponding to 50% cutoff wavelengths of 5.0μm at 77 K, the peak directivity of the detectors is 1.6× 10^{10} cm·Hz^{1/2}W^{-1} at 77 K.

In this work, p-n junctions are made from directly depositing optimal doped La_{1.85}Sr_{0.15}CuO_{4} (LSCO) films on n-type Nb-doped SrTiO_{3} substrates. Film thickness controlled rectifying behaviors are strikingly displayed. The starting points of the diffusion voltage reduction V_{d-on} change clearly with varying film thickness. V_{d-on} and T_{C} coincide with each other when the film thickness is larger than 300 nm, indicating a close relation between the two parameters. However, when the film is very thin (<350 nm) a departure between the two parameters was also observed. A possible reason for this is discussed within the framework of an inhomogeneous Schottky contact. Enhanced interface inhomogeneity due to the tensile strain appears to be the origin.

Based on both the spin diffusion equation and the Landau-Lifshitz-Gilbert (LLG) equation, we demonstrate the influence of out-of-plane spin torque on magnetization switching and susceptibility in a magnetic multilayer system. The variation of spin accumulation and local magnetization with respect to time are studied in the magnetization reversal induced by spin torque. We also research the susceptibility subject to a microwave magnetic field, which is compared with the results obtained without out-of-plane torque.

[Fe/Ni]_{N} multilayered structure grows epitaxially on the single crystalline MgO substrate. Due to the different directions of magnetic easy axes of Fe and Ni and the strong strain, large anisotropy dispersion is assumed. According to the layer model, the magnetization of Fe and Ni layers cannot follow each easy axis because of exchange coupling, and then the anisotropies are averaged out. The reduction of the effective anisotropy enhances with the decrease of periodic thickness. Thus, the coercivity of [Fe/Ni]_{N} multilayers reduces with decreasing periodic thickness.

Focal shift is inevitable in conventional lens systems due to the Fresnel number and angular aperture. In this Letter, we demonstrate that there is no focal shift when a paraxial Gaussian beam passes through a left-handed material slab lens without absorption or gain. However, the effect is exhibited in the presence of absorption or gain, and becomes larger as the absorption or gain increases. When the absorption is equal to the gain, the phenomenon of the focal shift caused by the gain is more obvious. In addition, the field distribution is not affected by the absorption or gain and always remains Gaussian both in internal and external focus planes.

A model for the effect of rapid thermal annealing on the formation of In-N clusters in strained GaInNAs is developed according to thermodynamics. In the model, the lowest annealing temperature influencing the redistribution of atoms is introduced. The average variation of energy for formation per In-N bond is obtained by fitting the experimental values. Using the present model, we calculate the average number of nearest-neighbor In atoms per N atom after annealing. The obtained results are compared with the experiment. The qualitative analysis and quantitative analysis are in good agreement with each other. The model is helpful to explain the essence of the blueshift caused by annealing.

CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY

We report the fabrication of high breakdown voltage metal-insulator-metal (MIM) capacitors with 200-nm silicon nitride deposited by plasma-enhanced chemical vapor deposition with 0.957 SiH_{4}/NH_{3} gas mixing rate, 0.9 Torr working pressure, and 60 W rf power at 250º chamber temperature. Some optimized mechanisms such as metal source wiping, pre-melting and evaporation rate adjustment are used for increasing the yield of the MIM capacitors. N_{2} annealing and O_{2}/H_{2} plasma pre-deposition treatment is proposed to increase the reliability of the MIM capacitors in high-temperature, high-pressure, and high-humidity environments. A 97% yield and up to 148 V breakdown voltage of a 13.06 pF MIM capacitor with 0.04 mm^{2} die area can be fabricated.

A series of Co_{0.48}(Alq_{3})_{0.52} granular films were deposited on silicon substrates using the co-evaporating technique. A crossover of magnetoresistance (MR) from negative to positive was observed in the samples, due to conducting channel switching. The transport properties of samples are greatly influenced by hydrofluoric acid pretreatment, as a result, positive MR decreases drastically and the temperature dependence of resistance changes a lot near room temperature. The result indicates that the native oxide layer plays an important role in the transport mechanism. Moreover, different resistivities of Si substrates influence the current distribution of conducting channels, leading to different transport behaviors accordingly.

The thermal stability of hydrogenated carbon films with H fraction from zero to 51.5% is studied by carrying out a molecular dynamical simulation on the annealing process in vacuum. Our simulations show that both graphitization temperature and dehydrogenization temperature decrease with H fraction in the films, which is in good agreement with the available experimental data. The dehydrogenization temperature is found to be much higher than the graphitization temperature. It is indicated that graphitization is the dominant process causing the degeneration of hydrogenated carbon films.

A simple yet accurate interconnect parasitical capacitance model is presented. Based on this model a novel interconnect bus optimization methodology is proposed. Combining wire spacing with wire ordering, this methodology focuses on bus dynamic power optimization with consideration of bus performance requirements. The optimization methodology is verified under a 65 nm technology node and it shows that with 50% slack in the routing space, a 33.03% power saving can be provided by the proposed optimization methodology for an intermediate video bus compared to the 27.68% power saving provided by uniform spacing technology. The proposed methodology is especially suitable for computer-aided design of nanometer scale on-chip buses.

Polycrystalline CdMnS and CdMnS:Au films with hexagonal structure on Si(111) substrates are prepared by co-evaporation, and exhibit ferroelectric and ferromagnetic properties, respectively. Under optimized growth conditions, CdMnS:Au samples with an average crystallite size of 90 nm and Mn concentration of 5.0 at.% are obtained, and an all-semiconductor spin valve device of Co/Au/CdMnS:Au/CdMnS/Pt is fabricated. Electrical measurement of the device reveals the clear dependence of resistance on applied magnetic field, with a relative magnetoresistance of 0.06% and a switching field of 100 Oe at 77k

We report on the fabrication and characterization of low-voltage indium-tin-oxide (ITO) thin-film transistors (TFTs) gated by Ba_{0.4}Sr_{0.6}TiO_{3} (BST) gate dielectric deposited at room temperature. The 400-nm-thick BST film shows a low leakage current density of 6× 10^{-8} A/cm^{2} and a high specific capacitance of 83 nF/cm^{2} (corresponding ε_{r=37).} The ITO TFTs gated by such BST dielectric operate in a depletion mode with an operation voltage of 5.0 V. The device exhibits a threshold voltage of -3.7 V, a subthreshold swing of 0.5 V/decade, a field effect mobility of 3.2 cm^{2}/Vs and a current on/off ratio of 1.4× 10^{4}.

We propose a physics method to study the effect of laser field and mechanical force on the melting process of double-stranded deoxyribonucleic acid (DNA). A two-dimensional lattice model is established for DNA molecules stuck on the surface, and the stretching energy of the hydrogen bond and stacking energy for each DNA molecule are calculated by using a nonlinear potential. A real-time algorithm is employed to deal with the dynamics process of DNA melting. Numerical results explain the experimental observations. The spatial distribution of the laser field determines the sequences of DNA melting. The simulation has shown the dependence of the final number of melted DNA on the laser field and mechanical force.

With income data from Chinese household income projects in 1998-2002, we study the functional form of Chinese income distribution. The fitting results suggest a log-normal distribution plus a power-law tail. This distributional form has changed a lot from its appearance in the early stage of China's reform and turns out to be consistent with that of some complete market economies. The uncertainty and diversity of income growth rate aroused by marketing reform are the main causes of current Chinese income distribution.

The concept of natural connectivity is reported as a robustness measure of complex networks. The natural connectivity has a clear physical meaning and a simple mathematical formulation. It is shown that the natural connectivity can be derived mathematically from the graph spectrum as an average eigenvalue and that it changes strictly monotonically with the addition or deletion of edges. By comparing the natural connectivity with other typical robustness measures within a scenario of edge elimination, it is demonstrated that the natural connectivity has an acute discrimination which agrees with our intuition.

The present study deals with Bianchi type-IX string cosmological models for perfect fluid distribution. We consider two cases: (i) ρ+λ =0, (ii) ρ-λ =0, whereρ and λ are the rest energy density and the tension density of a string cloud, respectively. The physical and geometrical properties of the models are discussed.

The paper published in Chin. Phys. Lett. 26 (2009) 124211 reported a Q-switched 2-μm Tm:YAG laser that is intracavity pumped by a Nd:YAG laser with emission at 1.06 μm. However, analysis of the experimental setup concludes that only the Nd:YAG laser is Q-switched, and the Tm:YAG laser operates in the free-generation regime. Therefore, Q-switch operation for the 2-μm emission wavelength is not realized.