We investigate the dynamic behavior of the magnetic domain wall under perpendicular magnetic field pulses in flat ferromagnetic nanowires using micromagnetic simulations. It is found that the perpendicular magnetic field pulse can trigger the magnetic domain wall motion, where all the field torques are kept on the plane of nanowire strip. The speed of magnetic domain walls faster than several hundreds of meters per second is predicted without the Walker breakdown for the perpendicular magnetic driving field stronger than 200 mT. Interestingly, the dynamic behavior of the moving magnetic domain wall driven by perpendicular magnetic field pulses is explained by charging- and discharging-like behaviors of an electrical RC-circuit model, where the charging and the discharging of magnetic charges on the nanowire planes are considered. The concept of the RC-model-like dynamic characteristic of the magnetic domain wall might be promising for the applications in spintronic functional devices based on the magnetic domain wall motion.

General dynamical networks with distributed time delays are studied. The topology of the networks are viewed as unknown parameters, which need to be identified. Some auxiliary systems (also called the network estimators) are designed to achieve this goal. Both linear feedback control and adaptive strategy are applied in designing these network estimators. Based on linear matrix inequalities and the Lyapunov function method, the sufficient condition for the achievement of topology identification is obtained. This method can also better monitor the switching topology of dynamical networks. Illustrative examples are provided to show the effectiveness of this method.

Quantum illumination, that is, quantum target detection, is to detect the potential target with two-mode quantum entangled state. For a given transmitted energy, the quantum illumination can achieve a target-detection probability of error much lower than the illumination scheme without entanglement. We investigate the usefulness of noiseless linear amplification (NLA) for quantum illumination. Our result shows that NLA can help to substantially reduce the number of quantum entangled states collected for joint measurement of multi-copy quantum state. Our analysis on the NLA-assisted scheme could help to develop more efficient schemes for quantum illumination.

We extend the Achlioptas percolation (AP) process [Achlioptas et al. Science 323 (2009) 1453] to two generalized Achlioptas percolation processes named GAP1 and GAP2. GAP1 induces a weighted probability factor α in the node sampling process and excludes the intracluster links. Based on GAP1, GAP2 requires m pairs of nodes sampled to add m candidate links that should be residing in 2m different clusters at each step. In the evolution of GAP1, the phase transition can evolve from the continuous to the 'most explosive' percolation as the value of the factor α is decreasing to a certain negative number. It indicates that there might be a type of discontinuous transition induced by the probability modulation effect even in the thermodynamic limit, and the most explosive percolation is only one of its extreme cases. We analyze the characteristics of the evolving process of the two-nodes-clusters and the cluster-size distribution at the transformation point for different α; the numerical results suggest that there might be a critical value α₀ and the phase transition should be discontinuous (α≤α₀) or continuous (α>α₀). In the evolution of GAP2, twice phase transitions are observed successively and the time duration between them becomes shorter till they amalgamate into the 'most explosive' percolation. The first transition is induced by the probability modulation effect analyzed in GAP1, the second transition, induced by the three coexisting giant clusters, is always discontinuous and the maximum jump of order parameter approaches N/3 while the value of the factor α is increasing to 1.4 approximately. In this work, two typical discontinuous transitions induced respectively by the probability modulation and the extended local competition are exhibited in GAP2, which might provide references to analyze the discontinuous phase transition in networks further.

Fast reactions between nitromethane and aluminium nanoparticles are studied using transient spectral methods. In comparison with species produced by pure nitromethane, the emergence time for species produced by nitromethane after addition of 1g of aluminium nanoparticles decreases by 46-58% and the emission intensity increases by 13-100%. The results demonstrate that aluminium nanoparticles have positive effect on accelerating the decomposition rate of nitromethane and that the explosion efficiency of nitromethane is greatly improved. Fast reactions carried out between nitromethane and aluminium nanoparticles in different environments (CO₂, H₂O and O₂) reveal that O₂ and an appropriate amount of H₂O improve the explosion efficiency of nitromethane, whereas CO₂ has the weakest effect on improving this parameter. The investigations provide insights into the process
occurring in actual systems involving propellants and fuel--air explosives.

We demonstrate a self-injection locking extended cavity diode laser (ECDL) using resonant optical feedback from the p-polarization of a monolithic folded Fabry–Perot parallel cavity (MFC). The full width at half maximum of the MFC resonance is 31 MHz. With the help of a narrow-linewidth reference laser, the linewidth of the ECDL is measured to be about 7 kHz. The frequency of the laser could be tuned at 160 MHz with an amplitude of 40 V by a PZT mounted on the monolithic cavity and the voltage tuning coefficient is about 4 MHz/V.

We propose a novel scheme for testing the equivalence principle with rotating cold polar molecules whose angular momenta are polarized at different states. Molecules in specific rotational states are selected out via the hexapole state-selection technique and the gravitational acceleration g of molecules is measured by measuring the Doppler shift of the molecules free falling in the gravitational field. Some other possible methods of rotating molecules and measuring g are also mentioned. Molecules, as the test masses, have higher rotating speed and smaller dimension in comparison with mechanical gyroscopes and may open a new way for testing the equivalence principle and the possible coupling between rotation and gravity.

We present the measurements of the temperature dependence of the internal quality factor (Q_i) of a microwave resonator, well below the superconducting transition temperature. The device is a quarter-wavelength niobium (T_c=9.2 K) coplanar waveguide resonator. The measured |S₂₁| parameter shows typically the skewed Lorentzian distributions, from which the fitted quality factor monotonically decreases with the temperature increasing from 30 mK to 900 mK. It is observed that for the lower temperature range (i.e., at T<700 mK) the temperature dependence of the fitted Q_i deviates significantly from the predictions of the usual Mattis–Bardeen theory. The measured 3 dB internal quality factor Q'_i also verifies such an anomalous temperature dependence. Physically, this phenomenon could be attributed dominantly to the effects of the two-level systems in the device, rather than the usual temperature-dependent complex conductance.

Based on nonequilibrium Green's function method and density functional theory calculations, we investigate theoretically the electronic transport properties of 1,4-bis(fullero[c]pyrrolidinl-yl)benzene (BDC60). A low bias negative differential resistance with the peak-to-valley ratio as high as 305.41 is obtained. The observed negative differential resistance is explained in terms of the evolution of the transmission spectra, molecular projected self-consistent Hamiltonian states and molecular projected energy levels with applied bias.

We present a multifractal detrended fluctuation analysis (MFDFA) of the time series of return generated by our recently-proposed Ising financial market model with underlying small world topology. The result of the MFDFA shows that there exists obvious multifractal scaling behavior in produced time series. We compare the MFDFA results for original time series with those for shuffled series, and find that its multifractal nature is due to two factors: broadness of probability density function of the series and different correlations in small- and large-scale fluctuations. This may provide new insight to the problem of the origin of multifractality in financial time series.

We present the simulation and characterization of several aluminium three-dimensional (3D) resonators, which can be used for superconducting quantum computation. By changing the conductivity of the aluminium in a high frequency structure simulator, the loaded quality factor at room temperature and base temperature (20 mK) can be simulated. From S₂₁ measurement, we can characterize the properties of the resonators. The simulated and experimental results can be fitted well by exponential equations.

The one- and two-periodic wave solutions for the Hirota–Satsuma (HS) equation are presented by using the Hirota derivative and Riemann theta function. The rigorous proofs on asymptotic behaviors of these two solutions are given such that soliton solution can be obtained from the periodic wave solution in an appropriate limiting procedure.

Quantum sensing, using quantum properties of sensors, can enhance resolution, precision, and sensitivity of imaging, spectroscopy, and detection. An intriguing question is: Can the quantum nature (quantumness) of sensors and targets be exploited to enable schemes that are not possible for classical probes or classical targets? Here we show that measurement of the quantum correlations of a quantum target indeed allows for sensing schemes that have no classical counterparts. As a concrete example, in the case that the second-order classical correlation of a quantum target could be totally concealed by non-stationary classical noise, the higher-order quantum correlations can single out a quantum target from the classical noise background, regardless of the spectrum, statistics, or intensity of the noise. Hence a classical-noise-free sensing scheme is proposed. This finding suggests that the quantumness of sensors and targets is still to be explored to realize the full potential of quantum sensing. New opportunities include sensitivity beyond classical approaches, non-classical correlations as a new approach to quantum many-body physics, loophole-free tests of the quantum foundation, et cetera.

Based on the two-component relativistic effective core potential and matched basis sets cc-pwcvnz-pp (n=Q, 5), combining the completed basis-set extrapolation of electronic correlation energy and the fourth-order polynomial fitting technique, the bond length and spectroscopic constants of Hg₂ are studied by the coupled cluster theory with spin–orbit coupling. Spin–orbit coupling is included in the post Hartree–Fock procedure, i.e., in the coupled-cluster iteration, to obtain more reliable theoretical results. The results show that our theoretical values agree with the experimental values very well and will be helpful to understand the spectral character of Hg₂.

Nickel ferrite nanoparicles with various grain sizes are synthesized using annealing treatment followed by ball milling of its bulk component materials. Commercially available nickel and iron oxide powders are first mixed, and then annealed at 1100°C in an oxygen environment furnace and for 3 h. The samples are then milled for different times in an SPEX mill. X-ray diffraction pattern indicates that in this stage the sample is single phase. The average grain size is estimated by scanning electron microscopy (SEM) and x-ray diffraction techniques. Magnetic behavior of the sample at room temperature is studied using a superconducting quantum interference device (SQUID). The Curie temperature of the powders is measured by an LCR–meter unit. The x-ray diffraction patterns clearly indicate that increasing the milling time leads to a decrease in the grain size and consequently leads to a decrease in the saturation magnetization as well as the Curie temperatures. This result is attributed to the spin-glass-like surface layer on the nanocrystalline nickel ferrite with a ferrimagnetically aligned core.

The off-state leakage current characteristics of nanoscale channel metal-oxide-semiconductor field-effect transistors with a high-k gate dielectric are thoroughly investigated. The off-state leakage current can be divided into three components: the gate leakage current, the source leakage current, and the substrate leakage current. The influences of the fringing-induced barrier lowering effect and the drain-induced barrier lowering effect on each component are investigated separately. For nanoscale devices with high-k gates, the source leakage current becomes the major component of the off-state leakage current.

Hot-carrier degradation for 90nm gate length lightly-doped drain (LDD) NMOSFET with ultra-thin (1.4nm) gate oxide is investigated under the low gate voltage stress (LGVS) and peak substrate current (I_sub,max) stress. It is found that the degradation of device parameters exhibits saturating time dependence under the two stresses. We concentrate on the effect of these two stresses on gate-induced-drain leakage (GIDL) current and stress induced leakage current (SILC). The characteristics of the GIDL current are used to analyse the damage generated in the gate-to-LDD region during the two stresses. However, the damage generated during the LGVS shows different characteristics from that during I_sub,max stress. SILC is also investigated under the two stresses. It is found experimentally that there is a linear correlation between the degradation of SILC and that of threshold voltage during the two stresses. It is concluded that the mechanism of SILC is due to the combined effect of oxide charge trapping and interface traps for the ultra-short gate length and ultra-thin gate oxide LDD NMOSFETs under the two stresses.

Fusion power output is proportional not only to the fuel particle number densities participating in reaction but also to the fusion reaction rate coefficient (or reactivity), which is dependent on reactant velocity distribution functions. They are usually assumed to be dual Maxwellian distribution functions with the same temperature for thermal nuclear fusion circumstances. However, if high power neutral beam injection and minority ion species ICRF plasma heating, or multi-pinched plasma beam head-on collision, in a converging region are required and investigated in future large scale fusion reactors, then the fractions of the injected energetic fast ion tail resulting from ionization or charge exchange will be large enough and their contribution to the non-Maxwellian distribution functions is not negligible, hence to the fusion reaction rate coefficient or calculation of fusion power. In such cases, beam-target, and beam-beam reaction enhancement effect contributions should play very important roles. In this paper, several useful formulae to calculate the fusion reaction rate coefficient for different beam and target combination scenarios are derived in detail.

Polarized $^{3}$He neutron spin filters (NSFs) can be used as a vital tool for neutron polarization production and analysis. The China Spallation Neutron Source (CSNS), as one of the major neutron facilities in China, has committed resources to the development of a polarized $^3$He NSF program to support its growing polarized neutron research. A spin-exchange optical pumping (SEOP)-based polarized $^{3}$He system and other necessary hardware for NSF transport has been recently developed. The performance of the system is benchmarked using an in-house developed cell named “Trident”. Neutron beam measurements yield a $^{3}$He polarization of 77% with over 200 h of on-beam relaxation time. Combining this newly developed SEOP system with the recently reported cell fabrication station, CSNS is now capable of the fully self-sustained production of $^{3}$He NSFs that shall support its future neutron polarization research.

ZnO films prepared at different temperatures and annealed at 900°C in
oxygen are studied by photoluminescence (PL) and x-ray photoelectron
spectroscopy (XPS). It is observed that in the PL of the as-grown films the green luminescence (GL) and the yellow luminescence (YL) are related, and after annealing the GL is restrained and the YL is enhanced. The O 1s XPS results also show the coexistence of oxygen vacancy (V_O) and interstitial oxygen (O_i) before annealing and the quenching of the V_O after annealing. By combining the two results it is deduced that the GL and YL are related to the V_O and O_i defects, respectively.

We present the multi-component Hunter–Saxton and μ−Camassa–Holm systems. It is shown that the multi-component Camassa–Holm, Hunter–Saxton and μ-Camassa–Holm systems are geometrically integrable, namely they describe pseudo-spherical surfaces. As a consequence, their infinite number of conservation laws can be directly constructed. For the three-component Camassa–Holm and Hunter–Saxton systems, their nonlocal symmetries depending on the pseudo-potentials are obtained.

Compared to AgNbO$_{3}$ based ceramics, the experimental investigations on the single crystalline AgNbO$_{3}$, especially the ground state and ferroic domain structures, are not on the same level. Here, based on successfully synthesized AgNbO$_{3}$ single crystal using a flux method, we observed the coexistence of ferroelastic and ferroelectric domain structures by a combination study of polarized light microscopy and piezoresponse force microscopy. This finding may provide a new aspect for studying AgNbO$_{3}$. The result also suggests a weak electromechanical response from the ferroelectric phase of AgNbO$_{3}$, which is also supported by the transmission electron microscope characterization. Our results reveal that the AgNbO$_{3}$ single crystal is in a polar ferroelectric phase at room temperature, clarifying its ground state which is controversial from the AgNbO$_{3}$ ceramic materials.

A deterministic direct quantum communication protocol is proposed by using swapping quantum entanglement and local unitary operations. The present protocol is secure for the proof of the security of the present scheme, the same as that in the two-step protocol [Phys. Rev. A 68(2003)042317]. Additionally, the advantages and disadvantages of the present protocol is also discussed.

We report an all-fiber two-stage high power pulsed amplifier, seeded with a 1550nm, 1kHz repetition rate rectangular pulse, and based on Er/Yb co-doped double clad fiber. All the characteristics are measured in the experiment. The maximal slope efficiency is 22.56%, which is the highest we know of at such a low repetition rate, and the maximal output signal power is 1W. The various factors that affect the pulsed amplifier performance are analyzed. A high output power while keeping high power conversion efficiency can be obtained with careful selection of the input power, pump power and repetition rate. The experimental results show that the crucial parameters should be optimized when designing all-fiber pulsed amplifiers.

Hydrogen-free silicon nitride (SiN_x) films were deposited at room temperature by microwave electron cyclotron resonance (MW-ECR) plasma enhanced unbalance magnetron sputtering system. Both Fourier-transform infrared spectroscopy and x-ray photoelectron spectroscopy are used to study the bonding type and the change of bonding structures of the silicon nitride films. The results indicate that the chemical structure and composition of SiN_x films deposited by this technique depend strongly on the N_x flow rates, the stoichiometric SiN_x film, which has the highest hardness of 22.9GPa, could be obtained at lower N_x flow rate of 4sccm.

Based on dislocation theory, we investigate the mechanism of strain rate effect. Strain rate effect and dislocation motion are bridged by Orowan's relationship, and the stress dependence of dislocation velocity is considered as the dynamics relationship of dislocation motion. The mechanism of strain rate effect is then investigated qualitatively by using these two relationships although the kinematics relationship of dislocation motion is absent due to complicated styles of dislocation motion. The process of strain rate effect is interpreted and some details of strain rate effect are adequately discussed. The present analyses agree with the existing experimental results. Based on the analyses, we propose that strain rate criteria rather than stress criteria should be satisfied when a metal is fully yielded at a given strain rate.

Undoped and copper doped zinc oxide (ZnO) thin films have been prepared on glass substrates by spray pyrolysis technique. The films were doped with copper using the direct method by addition of a copper salt (CuCl₂) in the spray solution of ZnO. Variation of structural, electrical, optical and thermoluminescence (TL) properties with doping concentrations is investigated in detail.

By solving the Boltzmann transport equation and considering the spin-dependent grain boundary scattering, the distribution of electrons in grains and the electrical transport properties in the applied magnetic field are studied. With regard to the dominant influence of grain boundary scattering which is taken as a boundary condition for the electrical transport, the grain size-dependent electrical conductivity is investigated. In addition, the reorientation of the relative magnetization between grains brings the change of the electron spin when the magnetonanocrystalline material is subjected to the magnetic field, resulting in the remarkable giant magnetoresistance effect.

Porous titanium and Ti6Al4V are produced by the powder metallurgy method. Dependence of the electrical conductivity on the porosity and pore size is investigated and the experimental results are correlative and compared with several earlier models. A newly modified Mori--Tanaka relationship based on the effective field method is proposed, which is successfully applied to describe the dependence of the electrical conductivity of porous titanium and Ti6Al4V on the porosity. The pore size has a minor effect on the electrical onductivity of both samples.

We investigate the methods to optimize the directivity of point source array by using pseudostochastic sequences. Maximum-length sequence (MLS) array and Quadratic-residue sequence (QRS) array are theoretically analysed, and their simulated responses are shown. The results indicate that pseudostochastic sequences can be used to optimize the directivity of point source array.