We introduce a dynamical decomposition view in dealing with Markov processes without detailed balance. This work generalizes a previous decomposition framework on continuous-state Markov processes and explicitly gives its correspondence in discrete-state case. We investigate the dynamical roles of decomposed parts by studying the evolution of relative-entropy-like functions. We find a special definition of relative entropy to unify the dynamical roles played by the detailed balance part and the breaking detailed balance part. The evolution of the relative entropy naturally bounds the convergence of the process.

We first note that the improved Boussinesq equation has a multisymplectic structure. Based on it, a multisymplectic scheme is proposed. Dispersion relations analysis and linear stability analysis show that the proposed scheme has excellent properties. Numerical results confirm the excellent long-term behavior of the proposed scheme.

Molecular spectroscopy is a branch of physics which deals with the interaction of electromagnetic radiation with matter. Using the new theoretical approach, i.e., Lie algebraic approach, we calculate the infrared spectra of phosphine in the range from 3000 cm^?1 to 9500 cm^?1 and nitrogen trifluoride in the range from 900 cm^?1 to 4500 cm^?1. The model Hamiltonian constructed seems to describe the P–H and N–F stretching modes accurately with only four numbers of parameters. The present calculation not only predicts the higher overtones but also shows good agreement with the few observed data.

The schematic optical realization of deterministic multicopy (three-copy) entanglement concentration under local operations and classical communication (LOCC) is presented, which can resort to the linear optical elements, controlled-NOT gate that uses weak cross-Kerr nonlinearity effect and entangled qudits with different degrees of freedom. This concentration is based on Nielsen's theorem, which in principle quantifies the unit success probability. In addition, the required positive operator-valued measurement (POVM) is implemented through direct sum extension, because the least number of ancillary dimensions is demanded. The construction of POVM is systematically formulated, which results in the feasibility to generate the protocol to n-copy (n>3) cases.

A canonical ensemble model for the black hole quantum tunneling radiation is introduced. With this model the probability distribution function corresponding to the emission shell is calculated. Comparing with this function, we investigate the statistical significance of the quantum tunneling radiation spectrum of black holes. Moreover, by calculating the entropy of the emission shell, a discussion about the mechanism of information flowing out from the black hole is given out.

The migration of living cells usually obeys the laws of Brownian motion. While the latter is due to the thermal motion of the surrounding matter, the locomotion of cells is generally associated with their vitality. We study what drives cell migration and how to model memory effects in the Brownian motion of cells. The concept of temperament is introduced as an effective biophysical parameter driving the motion of living biological entities in analogy with the physical parameter of temperature, which dictates the movement of lifeless physical objects. The locomemory of cells is also studied via the generalized Langevin equation. We explore the possibility of describing cell locomemory via the Brownian self-similarity concept. An heuristic expression for the diffusion coefficient of cells on structured surfaces is derived.

An adaptive control scheme is developed to study the synchronization and the anti-synchronization behaviors between two identical Lorenz–Stenflo systems with unknown parameters. This adaptive controller is designed based on Lyapunov stability theory and an analytic expression of the controller with its adaptive laws of parameters is shown. Theoretical analysis and numerical simulations are shown to verify the results.

By introducing weakly periodic perturbation given by light, the three-variable model of photosensitive Belousov–Zhabotinsky reaction with two time scales may possess two slow processes. The codimension-2 bursting called cusp bursting is novel, especially the phenomenon that is of the transiently quiescent state mixed among repetitively large amplitude oscillations. The slow-fast dynamics analysis with two slow parameters, based on overlapping the codimension-2 bifurcation diagram of the fast subsystem with the 3-dimensional transition phase portrait of the whole system, is proposed to reveal the bifurcation mechanism of bursting oscillation with two slow variables. The adjustment behavior of slow parameters is used to explain the transformation between the spiking state and quiescent state.

The stochastic resonance (SR) phenomenon induced by the periodic signal in a metapopulation system which is driven by noises and contains a time delay is investigated. Under the condition of small delay time, the analytical expression of signal-to-noise ratio (SNR) is derived in the adiabatic limit. Via numerical calculations, each effect of the additive noise intensity, the multiplicative noise intensity and the delay time upon the SNR is discussed, respectively. It is shown that both the additive noise intensity and the multiplicative noise intensity can play a role in restraining the SR phenomenon, and for the additive noise, even a very small intensity can excite the SR phenomenon. For the delay time, the different role upon the SR phenomenon is discovered finally.

The function projective synchronization between two coupled gyroscope systems is investigated under the sinusoidal constraints. From the theory of discontinuous dynamical systems, the necessary and sufficient conditions of such synchronization are given, and the parameter map is developed. Numerical simulations for the function synchronization of two coupled gyroscopes are illustrated to verify the effectiveness of this method.

The capability of a biological neuron to discriminate the intensity of external stimulus is measured in its dynamic range. In previous studies, a few factors have been reported to be able to enhance the dynamic range, e.g., electrical coupling and active dendrites. Here we numerically show that intrinsic channel noise within neurons has a subtle effect in neuronal dynamic range modulation. Our simulation results indicate that for relatively weak noise intensity, the dynamic range of the neuron is enhanced significantly. However, as the noise intensity becomes stronger, the dynamic range of the neuron is weakened. Further investigation suggests that sodium channel noise and potassium channel noise play opposite roles in modulating the dynamic range. Consequently, the model results suggest a new function of channel noise, that is, a proper value of noise intensity could optimize the dynamic range of neurons.

Effects of frequency variation on vacuum electron-positron pair production in strong pulsed laser fields are investigated in the framework of a quantum kinetic method. It is found that the slowly varying frequency can influence the pair production to some extent, while rapid varying frequency can increase the pair creation rate a few orders if the time lies within a narrow time window, in which frequency jump occurs. The possible physical mechanism behind the pair enhancement phenomenon is discussed briefly.

Neutron noise spectra in nuclear reactors are a convolution of multiple-induced reactivities. For the IBR-2 pulsed reactor (JINR-Dubna), one part is represented by the reactivities induced by the two moving reflectors, and the other part by other sources that are moderately stable. In the present study, using recordings of the mechanical noise of the two moving reflectors, their non-linear correlations into the power spectra of the reactor are extracted using statistical analysis. The remaining noise sources are moderately stable noise and can be further monitored by other automated reactor diagnoses.

The vector correlations in the title reaction at collision energies of 0.4–1.6 eV are studied by using the quasi-classical trajectory method on an accurate ¹A' potential energy surface (PES) to gain insight into the alignment and the orientation of the product molecules. The calculated results are compared with those on ³A" PES and different properties of vector correlations have been found. The influences of the PES and the collision energy on the product vector correlations as well as the reaction mechanism are discussed. The results demonstrate that the deep potential well and the collision energy display large effect on the product vector correlations. The title reaction occurring on ¹A' PES is dominantly controlled by indirect insertion mechanism.

By using B-spline basis set combined with model potential, energy levels and wave functions of rubidium atoms are obtained. Using a time-dependent multi-level approach, we study the dependence of the population of rubidium atoms excited from a low lying state to a target state on the parameters of a single or two broadband terahertz laser pulses. The population redistribution between the states n=23 and n=24 due to the interaction with terahertz pulses is analyzed in detail. Population oscillation in the initial and final states as a function of the time delay between two half cycle pulses is shown, and the oscillation period is the same as the Kepler period of the selected states. The calculation results agree well with the experiment and can be explained by the semiclassical picture.

Using a semiclassical model, we investigate the effect of the initial longitudinal velocity of the tunnel-ionized electron on low-energy structure (LES) in above-threshold ionization (ATI) spectra. Our analysis shows that the effect (reduction or enhancement) of the initial longitudinal velocity p_z0 on the LES is dependent on the direction of the initial longitudinal velocity. For the initial longitudinal velocity along the direction of the laser electric field at the moment of tunneling (i.e., p_z0>0), the Coulomb interaction between the photoelectron and ion core is enhanced, while for the initial longitudinal velocity in the opposite direction (i.e., p_z0<0), the Coulomb effect is reduced. Our work provides solid evidence that the initial electron longitudinal velocity has considerable effect on the photoelectron dynamics in the ATI process.

The momentum-space multichannel static-exchange-optical model is applied to the electron-H₂ collision at the two-state close-coupling level. Differential cross sections for X¹Σ_g to b³Σ_u transition at the energies of 20 and 30 eV are reported. Results are compared with other theoretical results and experimental data. Elastic scattering cross sections are also presented and compared with other work.

Photoassociation (PA) of cold atoms is a key tool widely used for accurate determination of long-range molecular potentials, measurement and tuning of interatomic interactions, as well as creation of desired cold molecules. We report the observation of PA spectra of ultracold ytterbium (Yb) atoms at the ¹S₀–³P₁ inter-combination line by detecting the resonant loss of atoms trapped in a crossed far-off-resonance trap (crossed-FORT). Eight vibrational levels in the ¹0⁺_u molecular state are observed for PA laser detunings up to 1 GHz with respect to the atomic resonance. The photoassociation resonances have a Lorentzian shape and sub-MHz linewidths due to the ultra low temperature of the atoms, and the resonance positions agree well with that predicted by the semiclassical formula.

The spatial manipulation of ionic qubits in a fast and precise fashion is one of the foremost issues in scalable quantum information processing with trapped ions. We report our recent efforts toward precise manipulation of trapped ions, including separation, recombination and reordering of the ions, in our home-made microscopic surface-electrode trap. We also demonstrate the micromotion compensation for the trapped ions by rf-photon cross-correlation, which ensures the cooling of the ions down to the temperature 23.3 mK.

A cascaded-cavity photodetector with subwavelength metallic slit is proposed to enhance responsivity and response speed simultaneously. Responsivity enhancement depends on light transmittance increased by using a subwavelength metallic slit plasmonic mode resonant cavity; it also relies on quantum efficiency improved by adopting a resonant cavity enhanced structure. Response speed improvement is due to low capacitance of metal-slit-metal and thin absorption layers. In the cascaded-cavity structure, the subwavelength metallic slit plays a vital role in performance improvements. Simulation results show that, for the optimized slit structure, responsivity enhancement of 80 times can be achieved compared to the conventional structure. In addition, response bandwidth of the optimized structure can reach 150 GHz.

We report a high power high beam quality quasi-continuous-wave (QCW) diode-end-pumped Nd:YAG slab amplifier at 1319 nm. The strongest 1064 nm parasitic oscillation has been successfully suppressed by reasonable coating design. In a five-pass configuration, the amplifier yields a 42.3 W linearly polarized 1319 nm output at repetition rate of 1 kHz with pulse duration of 75 μs and beam quality factors of M_x²=1.13 and M_y²=2.16 in the orthogonal directions. The fluctuation of the amplifier output power is measured to be ±0.6 %. Furthermore, a computational model of QCW pulse amplification is employed to examine the amplification process.

A single random phase encoding is introduced into ptychography for the first time. Since the diffractive wave front is encoded with the random phase modulator, the information of the sample cooperated with each probe can be uniformly distributed onto an entire diffraction pattern. It leads to the much faster convergent speed of the iterative algorithm for ptychographical imaging. It is more important for practice that the robustness to resist the noises and especially the transverse shift errors of probes are considerably improved compared with the conventional ptychographic algorithm.

A tunable grating-coupled external cavity (EC) laser is realized by employing a GaN-based laser diode as the gain device. A tuning range of 4.47 nm from 403.82 to 408.29 nm is achieved. Detailed investigations reveal that the injection current strongly influences the performance of the EC laser. Below the free-running lasing threshold, EC laser works stably. While above the free-running lasing threshold, a Fabry–Pérot (F-P) resonance peak in the emission spectrum and a smooth kink in the output power-injection current characteristic curve are observed, suggesting the competition between the inner F-P cavity resonance and EC resonance. Furthermore, the tuning range is found to be asymmetric and occurs predominantly on the longer wavelength side. This is interpreted in terms of the asymmetric gain distribution of GaN-based quantum well material.

A method to measure the end-output coupling efficiencies between silicon wire waveguides (SWWs) and optical fibers is proposed and demonstrated. The end-output coupling efficiency is calculated through four measured counting rates based on the correlated photon pair generation in the SWW. It provides a way to investigate and optimize the coupling processes at the input and output end of the optical waveguides separately.

We investigate and experimentally demonstrate the gain improvement of single-pump fiber parametric amplifiers by using a suitable length of standard single-mode fiber (SSMF) inserted between two high-nonlinear fibers (HNLFs). The SSMF with different dispersion properties from the HNLF is employed for phase matching of the parametric processes, and the signal gain is improved as compared with the absence of the SSMF with experiment results. Furthermore, the effect of the input pump power and the fiber length of the SSMF on the output signal gain are discussed with experimental investigation.

We demonstrate a 1030-nm laser with end-pumped slab Yb:YAG geometry at room temperature. A maximum power of 86 W output at the pump power of 323 W is obtained. The optical-optical efficiency is about 26.6% and the slope efficiency is 31%.

The band structures of two-dimensional (2D) gyromagnetic photonic crystals (PCs) are analyzed by a modified finite difference time domain (FDTD) method. A special implementation is used to tackle the magnetic constitution equation. This method avoids the discretizing complexity in the time domain caused by nonlinear frequency dependence of anisotropy permeability tensor, and therefore keeps the fully explicit nature of the original FDTD method. Our implementation is proved by the band structure calculations using other methods and the transmission measurements of 2D gyromagnetic PC involving circular ferrite rods and square rods.

Phonon lifetime is a significant parameter in the process of stimulated Brillouin scattering (SBS). In the present study, SBS slow light technique is used to measure phonon lifetime. Brillouin bandwidth is divided into natural, spontaneous and stimulated bandwidth. Compared with the traditional heterodyne-detection and pump-probe techniques, the natural Brillouin bandwidth can be obtained by SBS slow light technique, which equals the reciprocal of phonon lifetime and has no relations with the pump power. Another advantage of this technique is that the effect of polarization can be excluded. The natural Brillouin bandwidth is measured to be ～50 MHz and the phonon lifetime ～3.2 ns in the conventional single-mode fiber (SMF) at room temperature and zero strain. The obtained results are guidable in applications where the phonon lifetime information is a requisite such as phase conjugation and pulse compression.

The direct global matrix approach can be applied to modeling of range-dependent sound propagation in order to achieve numerically stable and accurate solutions. By solving the global system directly, this method features high efficiency as well as accuracy by avoiding error accumulation. It is an important issue to solve linear systems numerically in the direct global matrix approach, especially for the large-scale problems. An efficient and memory-saving algorithm is developed for solving the global system, in which the global coefficient matrix is treated as a block pentadiagonal matrix. As a result, this numerical model has the ability to solve large-scale problems on regular computers. Numerical examples are also presented to demonstrate the accuracy and efficiency of this method.

A combined time and frequency domain method is developed for the calculation of a shock wave induced by a strong focused ultrasound transducer in the oblate spheroidal coordinate system. The spheroidal beam equation (SBE) is utilized to describe the nonlinear sound propagation; the diffraction and attenuation effects are calculated in the frequency-domain, while the nonlinear effect is calculated in the time-domain. Compared with the traditional frequency-domain method, this method could calculate the shock wave effectively without oscillation at the shock front and with less computation time. When the harmonic number is 200, the computation time by this method is about 1/16 of that used by the traditional frequency-domain method.

Numerical simulations on coalescence of binary equal-sized droplets with surface tension gradients are carried out by using the front tracking method. Mixing process of the fluid from each droplet is investigated. The tangential flow caused by the Marangoni effect and the interface replacement by the fluid with small surface tension coefficient are simulated successfully. Asymmetry caused by the surface tension gradients can generate some extent of mixing within the coalesced droplet. The effects of the surface tension gradients and viscosity on the tangential velocity, replacement time of interface and mixing are investigated.

An immersed boundary (IB)-lattice Boltzmamm method (LBM) coupled model is utilized to study the particle focusing in a straight microchannel. The LBM is used to solve the incompressible fluid flow over a regular Eulerian grid, while the IB method is employed to couple the bead-spring model which represents the fluid-particle interaction. After model validation, the simulations for hydrodynamic focusing of the single and multi particles are performed. The particles can be focused into the equilibrium positions under the pressure gradient and self-rotation induced forces, and the particle radius and Reynolds number are the key parameters influencing the focusing dynamics. This work demonstrates the potential usefulness of the IB-LBM model in studying the particle hydrodynamic focusing.

The transient burst of an internal kink mode is first observed in EAST heavy impurity ohmic plasma. The features of the electron fishbone-like mode are presented, and the fishbone-like instabilities are found to be driven by the trapped supra-thermal electrons. The processional frequency of the trapped supra-thermal electrons is calculated with different discharge parameters. The results indicate that the calculated processional frequency is consistent with the experimental observations. Furthermore, we also find that the frequency chirping of the long-lived mode is related to the evolution of the safety factor profile.

Re-deposition is a non-volatile etching by-product in reactive ion etching systems that is well known to cause dirt on etching work. In this study, we propose a novel etching method called the polymer-rich re-deposition technique, used particularly for improving the etched sidewall where the re-deposition is able to accumulate. This technique works by allowing the accumulated re-deposition on the etched sidewall to have a higher polymer species than the new compounds in the non-volatile etching by-product. The polymer-rich re-deposition is easy to remove along with the photo-resist mask residual at the photo-resist strip step using an isopropyl alcohol-based solution. The traditional, additional cleaning process step used to remove the re-deposition material is not required anymore, so this reduces the overall processing time. The technique is demonstrated on an Al₂O₃-TiC substrate by C₄F₈ plasma, and the EDX spectrum confirms that the polymer re-deposition has C and F atoms as the dominant atoms, suggesting that it is a C–F polymer re-deposition.

Based on modification of the simplified coherent potential approximation, a model for the band-gap energy of In_xGa_yAl_1?x?yN is developed. The parameters of the model are obtained by fitting the experimental band-gap energy of their ternary alloys. It is found that the results agree with the experimental values better than those reported by others, and that the band-gap reduction of In_xGa_yAl_1?x?yN with increasing In or Ga content is mainly due to enhanced intraband coupling within the conduction band, and separately within the valence band.

We investigate the photoluminescence (PL) emission from InGaN/GaN multiple quantum-well structures before and after 1 MeV electron irradiation. The PL peak intensity exhibits a slight enhancement after low-dose electron irradiation (2×10¹³ e/cm²), and then decreases with the cumulative electron dose. Meanwhile, the full width at half maximum of the PL spectrum narrows after low-dose electron irradiation and widens when the irradiation dose is relatively high. With respect to the yellow photoluminescence, there is no significant change until the electron fluence has accumulated up to 10¹⁴ e/cm².

The effect of temperature, T, on the ductility of nanocrystalline (NC) Cu films of different thicknesses on flexible substrates is studied by uniaxial tension. It is found that the NC Cu films will fracture more easily with increasing T, exhibiting the anomalous T effect compared with that of bulk NC metals and freestanding films. Moreover, the T dependence of ductility becomes stronger for thinner films due to the larger decrement of the interfacial strength in thinner films. T-induced softening of the stretchable substrate reduces the interface constraint ability for suppressing strain localization, leading to the anomalous T effect.

The quasi-static and dynamic compressive mechanical properties of a bullet composite are investigated using the scattered spot technique, an electronic universal testing machine, and a Split–Hopkinson pressure bar. The stress-strain curves under static and dynamic loading are also obtained, and the strain rate effect is analyzed. The rupture structure is observed under a scanning electron microscope, and the microscopic damage mechanism of the bullet composite is examined. Results show that the composite is sensitive to the strain rate, such that the compressive strength of the composite increases with increased strain rate. The relationship of the compressive strength and elastic modulus with the logarithmic strain rate is nonlinear.

Using cell dynamics system simulation, we provide a simple way to form differently ordered patterns in a photosensitive, immiscible ABC ternary blend. The first pattern is established by irradiating the sample through a mask, which serves to pin the non-photoactivity C regions and thereby promotes the self-assembly of A and B into ordered domains. When the mask is removed, the photoactivity of the AB blend leads to different periodic patterns. Thus, the use of one mask permits the creation of multiple ordered morphologies, which can be stable for a long time by quenching the system at the appropriate time or choosing a suitable composition ratio and mask shape. Furthermore, the influence on the morphology of the composition ratio, the shape of the mask, and the illumination intensity are studied systematically.

We explore the Potts model on the generalized decorated square lattice, with both nearest (J₁) and next-nearest (J₂) neighbor interactions. Using the tensor renormalization-group method augmented by higher order singular value decompositions, we calculate the spontaneous magnetization of the Potts model with q = 2, 3, and 4. The results for q = 2 allow us to benchmark our numerics using the exact solution. For q = 3, we find a highly degenerate ground state with partial order on a single sublattice, but with vanishing entropy per site, and we obtain the phase diagram as a function of the ratio J₂/J₁. There is no finite-temperature transition for the q = 4 case when J₁ = J₂, whereas the magnetic susceptibility diverges as the temperature goes to zero, showing that the model is critical at T = 0.

First principles calculations based on the density functional theory of the electronic structure, elastic and lattice vibrational properties of orthorhombic CaSnO₃ are carried out using standard functional approximation and density functional perturbation theory. The results show that CaSnO₃ is an insulator with an indirect local density approximation and generalized gradient approximation gap of 3.10(2.69) eV. In addition, the Raman vibration modes of CaSnO₃ are determined by the calculated phonon frequencies at the gamma point, where the prominent peaks of the Raman spectra of CaSnO₃ coinciding with the calculated frequencies can be assigned.

Relativistic density functional calculations are performed to explore the promise of MAu₁₆(M=Si, Ge, and Sn) clusters as magic clusters and building blocks in developing cluster-assembled materials. C₁ and C_s, two isomers of SiAu₁₆, GeAu₁₆ and SnAu₁₆ with M (Ge or Sn) at the center of the cage, named, respectively, as SiAu₁₆–C₁, SiAu₁₆–C_s, GeAu₁₆-center, and SnAu₁₆-center, are calculated to be the most stable. The Au–M bond should have both ionic and covalent characteristics. Their static linear polarizabilities and first-order hyperpolarizabilities are found to be sensitive to the delocalization of the valence electrons of the M atom, as well as their structures and shapes.

We investigate the effects of ultraviolet (UV) irradiation treatment with varying irradiation intensities for different treatment times of poly(3, 4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) film on the performance and stability of polymer solar cells (PSCs) based on regioregular poly(3-hexylthiophene) (P3HT) and methanofullerene [6,6]-phenyl C₆₁-butyric acid methyl ester (PCBM) blend. Ultraviolet-visible transmission spectra, x-ray photoelectron spectroscopy, contact angle measurement, atomic force microscopy and the Kelvin probe method are conducted to characterize the UV-treated PEDOT:PSS film. The results demonstrate that UV treatment can improve the power conversion efficiency (PCE) and stability of PSCs effectively. The best performance is achieved under 1200 μW/cm² UV treatment for 50 min. Compared to the control device, the optimized device exhibits enhanced performance with a V_oc of 0.59 V, J_sc of 12.3 mA/cm², fill factor of 51%, and PCE of 3.64%, increased by 3.5%, 33%, 8.7% and 50%, respectively. The stability of the PSCs is enhanced by 2.5 times simply through the UV treatment on the PEDOT:PSS buffer layer. The improvement in the device performance and stability is attributed to the improvement in the wettability property and the increase in the work function of the PEDOT:PSS film by UV treatment, while the impact of UV treatment on the transparency of the PEDOT:PSS film is negligible. The strategy of using UV treatment to improve device performance and stability is attractive due to its simplicity, cost-effectiveness, and because it is suitable for large-scale commercial production.

First-principles calculations of the electronic structure and linear optical properties of metallic carbon nanotubes are carried out using the full-potential linear-augmented plane-wave method. The effect of intraband transition and electric-field polarization on the optical spectra of (5,2) chiral, (15,0) zigzag, and (8,8) armchair metallic carbon nanotubes are investigated. The optical spectra are calculated for both electric-field polarizations, parallel and perpendicular to the axis of the tube. It is revealed that the optical spectra are anisotropic along these two polarizations. For the parallel polarization to the tube axis, adding the intraband transition contributions shows that the dielectric function has singularity at zero frequency due to the screening effect in metallic carbon nanotubes.

We analyze aspects of nuclear dark states. The formation of the dark states prevents the further establishment of nuclear polarizations, while inhomogeneous nuclear spin precessions can result in leakage from these states. An optimal efficiency for pumping nuclear polarization is achieved when the dynamical nuclear polarization (DNP) cycling rate is comparable to the dark-state leakage rate. When the DNP rate is much larger, the nuclear spin bath can be locked on the dark states. We propose schemes where the inhomogeneous precessions can be suppressed for the realization of large-scale dark states. As the dark states correspond to low transverse nuclear field fluctuations, they can be used to suppress the decoherence of the electron induced by the nuclear spins.

Room-temperature negative differential resistance (NDR) characteristics are observed in a nanocrystalline Si quantum dot (nc-Si QD) floating-gate MOS structure, which is fabricated by plasma-enhanced chemical vapor deposition. Clear multi-NDR peaks for the electrons and holes, shown in the I–V curves, which are significant for the application of multiple value memory and logic, are proved to be induced by electron and hole resonant tunneling into the nc-Si QDs from the substrate. The calculation results indicate that these NDR characteristics should be associated with the Coulomb blockade effect and the quantum confinement effect of the nc-Si QDs. Furthermore, low-temperature I–V characteristics are also investigated to confirm the room-temperature results.

We theoretically investigate the effects of quantum size and doping concentration on the current-voltage characteristics of GaN resonant tunneling diodes. The results show a marked dependence of the peak current density on the emitter and collector spacers, and the existence of some thickness in the emitter, for which the electric current density reaches its maximum with a large peak-to-valley ratio. We also study the effect of the doping concentration in the emitter and collector layers. It is found that the doping concentration can greatly affect the current-voltage characteristics. In particular, it increases the peak of the current density and displaces the position of the maxima of the current dependence on the applied bias voltage. The effects of aluminum concentration and temperature are also presented. Finally, it is demonstrated that it is possible to have a symmetrical current for applying bias voltage in both directions by adjusting the thickness of the collector spacer.

A two-band Hamiltonian for β-graphyne is derived by the k?p method. The energy dispersions around the Dirac points are analytically obtained depending on the relative amplitude of the hopping terms t₁/t₂, and the Dirac cones are elliptical when ?2t₁/t₂j. This interesting feature is useful for direction-dependent wave filter devices.

The influence of ⁶⁰Co (γ-ray) irradiation on the electrical characteristics of Al/Si₃N₄/p-Si (MIS) structures is investigated using capacitance-voltage (C–V) and conductance-voltage (G/ω–V) measurements. The MIS structures are exposed to a ⁶⁰Co γ radiation source at a dose of 0.7 kGy/h, with a total dose range of 0–100 kGy. The C–V and G/ω–V properties are measured before and after ⁶⁰Co γ-ray irradiation at 500 kHz and room temperature. It is found that the capacitance and conductance values decrease with the increase in the total dose due to the irradiation-induced defects at the interface. The results also indicate that γ radiation causes an increase in the barrier height ?_B, Fermi energy E_F and depletion layer width W_D. The interface state density (N_ss), using the Hill–Coleman method and dependent on radiation dose, is determined from the C–V and G/ω–V measurements and decreases with an increase in the radiation dose. The decrease in the interface states can be attributed to the decrease in the recombination centers and the passivation of the Si surface due to the deposition insulator layer (Si₃N₄). In addition, it is clear that the acceptor concentration N_A decreases with increasing radiation dose. The profile of series resistance R_s for various radiation doses is obtained from forward and reverse-biased C–V and G/ω–V measurements, and its values decrease with increasing radiation dose, while it increases with increasing voltage in the accumulation region

An nc-Si floating gate MOS structure is fabricated by thermal annealing of SiN_x/a-Si/SiO₂. There are nc-Si dots isolated by a-Si due to partial crystallization. Conductance-voltage (G–V) measurements are performed to investigate the effect of multiple interface states including Si-sub/SiO₂, a-Si related (as-deposited sample) and nc-Si (annealed sample) in a charge trapping/releasing process. Double conductance peaks located in the depletion and weak inversion regions are found in our study. For the as-deposited sample, the Si-sub/SiO₂ related G–V peak with weak intensity shifts to the negative as test frequency increases. The a-Si related G–V peak with strong intensity shifts slightly with the increasing frequency. For the annealed sample, little change appears in the intensity and shift of Si-sub/SiO₂ related G–V peaks. The position of a-Si/nc-Si related peak is independent of frequency, and its intensity is weaker compared to that of the as-deposited sample. It is also found that as the size of nc-Si becomes larger, the a-Si/nc-Si related peak shifts to the depletion region due to the size effect of nc-Si.

We demonstrate experimentally a intriguing Fano-resonance in a perforated planar metamaterial with hole and slit pairs. The transmission strength of the Fano-resonance is modulated by interference between the composite diffracted evanescent wave and the direct transmission field instead of by the coupling between two plasmonic modes. Our metamaterials might have potential applications in future designs of plasmonic devices.

The highly accurate full-potential linearized augmented plane wave plus local orbital method is employed to calculate the structural, electronic and transport properties of HgIn₂S₄ and ZnIn₂S₄. For ZnIn₂S₄, the calculated In–S bond length is in good agreement with the experimental data. Bulk moduli results suggest that ZnIn₂S₄ can afford more compressional effects than HgIn₂S₄. The present study confirms that both HgIn₂S₄ and ZnIn₂S₄ are indirect band gap materials with band gap values of 0.705 eV and 1.533 eV respectively. The localized region existing in the most bottom valance band of both materials splits into states by 1 eV energy difference under the spin orbital coupling effect. Contour plots of charge density predict that chemical bonding in these compounds is a mixture of ionic and covalent characteristics. Effective mass results reveal that mobility of charge carriers in ZnIn₂S₄ is greater than that in HgIn₂S₄.

We report an optical spectroscopy study on an iron-selenide single crystal of insulating Cs_0.8(Fe_1.05Se)₂ with relatively high Néel temperature. The resistivity and magnetization measurements reveal a semiconductor behavior with T_N=492 K. The sample has been examined in the temperature range from 10 K up to 500 K by using infrared measurement. The low frequency optical measurement implies an insulating response with a major absorption near 0.31 eV. The double-peak structure in the mid-infrared region and the low-frequency phonon modes support the presence of the blocked anti-ferromagnetism. The infrared measurement reveals no signature of SDW-type energy gap formation below the anti-ferromagnetic-order temperature.

We investigate a Josephson junction between a one-band and a multi-band s-wave superconductor. When the multi-band lead is an s_±-wave superconductor, we find that the critical Josephson current may change its sign when the temperature changes. Our result confirms that this is a widespread effect of the s_±-wave superconductor, independent of the type of the junction, the ratios of the gaps and superconducting transition temperatures, as long as the tunneling matrix elements have suitable values. This novel effect comes directly from the opposite gap signs. We propose that the observation of this phenomena can be used to detect the s_±-wave pairing symmetry in iron-based superconductors.

The substitution of divalent cations of alkaline-earth elements in nanodimensional structures of rare-earth manganites produces advanced materials with potential electrical and magnetic functionalities. A systematic investigation of La_0.65A_0.35MnO₃ (A = Ca, Sr, Ba) materials synthesized with a modified citrate route adopting ethanol dehydration has been undertaken. The structural and morphological analyses are carried out by using x-ray diffraction and scanning electron microscopy, respectively. Resistivity measurements are performed in variation with temperature to study the electrical transport properties which are found to vary with the size of the A-site cationic radius. Room temperature magnetic measurements are carried out to investigate the type of magnetic phase present in materials. The stability of the magnetic phase and coercivity are found to be dependent on the size of nanocrystallites.

The carrier doping effects on the magnetic properties of defective graphene with a hydrogen chemisorbed single-atom vacancy (H-GSV) are investigated by performing extensive spin-polarized first-principles calculations. Theoretical results show that the quasi-localized p_z-derived states around the Fermi level are responsible for the weakened magnetic moment (MM) and magnetic stabilized energy (MSE) of the H-GSV under carrier doping. The mechanism of reduced MSE in the carrier doped H-GSV can be well understood by the Heisenberg magnetic coupling model due to the response of these p_z-derived states to the carrier doping. Within the examined range of carrier doping concentration, the total MM of H-GSV is always larger than 1.0μ_B with μ_B representing the Bohr magneton, which is mainly contributed by the localized sp² states of the unsaturated C atom around the vacancy. These findings of H-GSV provide fundamental insight into defective graphene and help to understand the related experimental observations.

N-doped In₂O₃ films were deposited on fused quartz substrates by radio-frequency magnetron sputtering with different N₂ flux. X-ray diffraction patterns, x-ray photoelectron spectroscopy and the optical transmittance spectra indicate that nitrogen has incorporated into the In₂O₃ lattice. Room-temperature d⁰ ferromagnetism is observed in all the films. The saturation magnetization increases from 0.73 to 3.5 emu/cm³ when the N₂ flux varies from 0 to 10 sccm. The concordant results in structural, compositional, optical and magnetic properties suggest that this d⁰ ferromagnetism is associated with the N incorporation and may be mediated by the long-range p–p interaction between the N 2p states.

Wafer-scale flexible surface acoustic wave (SAW) devices based on AlN/silicon structure are demonstrated. The final fabricated devices with a 50μm-thickness silicon wafer exhibit good flexibility with a bending curvature radius of 8 mm. Measurements under free and bending conditions are carried out, showing that the central frequency shifts little as the curvature changes. SAW devices with central frequency about 191.9 MHz and Q-factor up to 600 are obtained. The flexible technology proposed is directly applied to the wafer silicon substrate in the last step, providing the potential of high performance flexible wafer-scale devices by direct integration with mature CMOS and MEMS technology.

The laminate composites that can show the magneto-birefringence effect are suggested and fabricated by the product of magnetostriction and stress-birefringence. Under a magnetic field no stronger than 1900 Oe, a phase difference of ～3.3π is observed for a trilayer composite Tb_1?xDy_xFe_2?y/polycarbonate/Tb_1?xDy_xFe_2?y with a polycarbonate layer at a size of 5 × 2.75 × 20 mm³ at room temperature, resulting in a half-wave magnetic field of no greater than 270 Oe.

We illustrate that three identical nanocylinders self-assembled into a trimer with a small interparticle gap separation support strong Fano-like interference. The asymmetry line shape of the Fano-like resonance can be controlled by modifying the cluster structures, and a narrow linewidth between a peak and a dip is displayed in the line trimer. The resonant behaviors of the trimers could be strengthened by increasing the permittivity of the nanorods, and the asymmetry resonance is highly sensitive to the angle of the incident wave due to the orientation-dependent coupling between the cylinders in the cluster. The present study provides a way to investigate the environmental change caused by the reshaped asymmetry line, which can be applied to future high-performance resonance sensors.

We report on an order-reversed quenching phenomenon in manganese nitrides under flash melting, which prevents the thermodynamically favorable phase transformations from occurring at high temperatures by providing a narrow window of time. The Mn-N kept un-decomposed at high temperatures generated by current up to 339 MA/m² within 60 ms. After flash melting, the Mn-N shows a significantly enhanced coercivity and a decreased crystalline size. The Mn-N samples decompose rapidly at temperatures above 1100 K with time. The order-reversed quenching technique is potentially useful in processing and preventing phase transformations of meta-stable materials at high temperatures.

A novel silicon-on-insulator (SOI) trench metal-oxide-semiconductor field effect transistor (MOSFET) with a reduced specific on-resistance (R_{on, sp}) is presented. It features an oxide-filled trench and a non-depleted embedded p-type island (p-SOI). The oxide trench folds the drift region into a U-shape, resulting in a reduction in cell pitch and R_{on, sp}. The non-depleted p-island is employed to further reduce R_{on, sp} by increasing the optimized doping concentration of the drift region without deteriorating the breakdown voltage (BV). The simulation results show that the p-SOI decreases the R_{on, sp} to 10.2 mΩ?cm² from 17.4 mΩ?cm² of the conventional SOI MOSFET at the same BV.

We report on the photoluminescent characteristics of InGaN/GaN multiple quantum well (MQW) nanorod arrays with high internal quantum efficiency. The InGaN/GaN MQWs are grown by metalorganic chemical vapor deposition on c-plane sapphire substrates, and then the MQW nanorod arrays are fabricated by using inductively coupled plasma etching with self-assembled Ni nanoparticle mask with low-damage etching technique. The typical diameter of the nanorods is from 200 nm to 300 nm and the length is around 800 nm, which almost is dislocation free. At room temperature, an enhancement of 3.1 times in total integrated photoluminescence intensity is achieved from the MQW nanorod arrays, in comparison to that of the as-grown MQW structure. Based on the temperature-dependent photoluminescence measurements, the internal quantum efficiency of the nanorod structure is 59.2%, i.e., 1.75 times of as-grown MQW structure (33.8%). Therefore, the nanorod structure with a significant reduction of defects can be a very promising candidate for highly efficient light emitting devices.

We report the demonstration of a monolithic phase shifter employing Bi_1.5Zn_1.0Nb_1.5O₇ (BZN)/Ba_0.5Sr_0.5TiO₃ (BST) thin films on sapphire substrates. The BST and BZN thin films are successively deposited by radio?frequency magnetron sputtering. A distributed phase shifter with a coplanar?waveguide transmission line periodically loaded with the BZN/BST capacitors is fabricated. The return loss of the circuit is better than -13 dB from 1 to 12 GHz, and it provides 65° phase shift with an insertion loss of -4 dB at 12 GHz. The results show that BZN/BST thin films are promising candidate dielectrics for rf/microwave tunable applications.

In interdigitated back contact (IBC) solar cells, the metal-electrode coverage on a p-type emitter is optimized by a PC2D simulation. The result shows that the variation of the metal coverage ratio (MCR) will affect both the surface passivation and the electrode-contact properties for the p-type emitter in IBC solar cells. We find that when R_c ranges from 0.08 to 0.16Ω?cm², the MCR is optimized with a value of 25% and 33%, resulting in a highest energy-conversion efficiency. The dependences of both V_oc and fill factor on MCR are simulated in order to explore the mechanism of the IBC solar cells.

The problem of definite information leakage existing in the controlled bidirectional quantum direct communication protocol using GHZ states [Chin. Phys. Lett. 23 (2006) 1680] was pointed out by Ye and Jiang [Chin. Phys. Lett. 30 (2013) 040305]. Then, they proposed two strategies to improve this security bug. However, if the revised versions are analyzed from the viewpoint of information theory, it can be found that they still have the problem of information leakage. That is, three quarters and one half of the information interchanged by the communication parties are leaked out unknowingly in the first and second revised protocols, respectively.

Most recently, Liu and Chen [Chin. Phys. Lett. 30 (2013) 079901] used the tool of information theory to analyze the security of our two improved versions of the MX protocol [Chin. Phys. Lett. 30 (2013) 040305], and they found out that our two improved versions still have the information leakage problem. After revisiting them with the tool of information theory again, with respect to the security, we draw the same conclusion as Liu and Chen. In addition, we point out that how to use a single quantum state as the sole quantum resource to design a bidirectional quantum secure direct communication protocol without information leakage is still a big challenge that needs to be solved.

We point out that the quantum secret sharing (QSS) protocol proposed by Gao et al. [Chin. Phys. Lett. 29 (2012) 110305] has some defects. Thus, some strategies are given to mend them.

We first make a small modification to the improved protocol in order to enhance its efficiency. Secondly, the explanation that our improved protocol can prevent Trent from using the {|Ψ^±₂>,|Φ^±₂>} basis is given.