Showing papers in "Chinese Physics Letters in 2013"
TL;DR: In this paper, the authors studied the thermodynamics of a charged AdS black hole in the special f(R) correction with the constant Ricci scalar curvature and showed that the ratio ρc occurring at the critical point increases monotonically with the derivative term f'(R0), and that the critical exponents are the same as those of the liquid-gas phase transition in the van der Waals model.
Abstract: We study the thermodynamics of a charged AdS black hole in the special f(R) correction with the constant Ricci scalar curvature. Our results show that the f(R) correction influences the Gibbs free energy and the phase transition of system. The ratio ρc occurring at the critical point increases monotonically with the derivative term f'(R0). We also disclose that the critical exponents are the same as those of the liquid-gas phase transition in the van der Waals model, which does not depend on the f(R) correction considered here.
113 citations
TL;DR: In this paper, the total reciprocal space magnetic flux threading through a closed Fermi surface is a topological invariant for a three-dimensional metal, and the invariant is nonzero for each of its Fermian surfaces.
Abstract: The total reciprocal space magnetic flux threading through a closed Fermi surface is a topological invariant for a three-dimensional metal. For a Weyl metal, the invariant is nonzero for each of its Fermi surfaces. We show that such an invariant can be related to the magneto-valley-transport effect, in which an external magnetic field can induce a valley current. We further show that a strain field can drive an electric current, and that the effect is dictated by a second-class Chern invariant. These connections open the pathway to observe the hidden topological invariants in metallic systems.
101 citations
TL;DR: The controlled bidirectional quantum secure direct communication protocol based on the second approach is more convenient to implement than the MX protocol, since it merely uses a Bell state as the quantum resource and only needs to perform the Bell-basis measurement.
Abstract: The security of controlled bidirectional quantum direct communication using a GHZ state [Chin. Phys. Lett. 23 (2006) 1680] is analyzed. It turns out that the MX protocol has the problem of definite information leakage, i.e., the first bit of a secret message from any communication party is always leaked out without any active attack after the controller's announcement of measurement results. We put forward two approaches to improve this. The first is to merely modify the encoding rule of the MX protocol, while the second is to use a Bell state as the quantum resource instead of a GHZ state. Both our approaches can ensure that all the bits of secret messages from two communication parties are not leaked out after the controller's announcement of measurement results. Moreover, the controlled bidirectional quantum secure direct communication protocol based on the second approach is more convenient to implement than the MX protocol, since it merely uses a Bell state as the quantum resource and only needs to perform the Bell-basis measurement.
84 citations
TL;DR: In this article, the authors used FTIR spectroscopy associated with the degree of cross-linking of starch granules and compared the results with the tablet samples of native starch.
Abstract: Tapioca is economical crop grown in Thailand and continues to be one of the major sources of starch. Nowadays, tapioca starch has been widely used in industrial applications, however the native form of starch has limited the applications. Thus scientists try to modify the properties of starch for increasing the stability of the granules, pastes to low pH, heat, and shear during the food process. We modify the tapioca starch by plasma treatment under an argon atmosphere. The degree of modification is determined by following water content in the starch granules. The tablet samples of native starch are also prepared and compared with the plasma treated starch. Before plasma treatment, the starch tablets are stored under three different relative humilities (RH) including 11%, 68%, and 78%RH, respectively. The samples are characterized using FTIR spectroscopy associated with the degree of cross-linking. The results show that the water molecules are engulfed into the starch structure in two ways, a tight bond and a weak absorption of water molecules which is represented at two wave number of 1630 cm−1 and 3272 cm−1, respectively. The degree of cross-linking can be identified from the relative intensity of these two peaks with the C—O—H peak at 993 cm−1. The results show that the degree of cross-linking increase in the plasma treated starch. The degree of cross-linking of the treated starch with high relative humidity is less than that of the treated starch with low relative humidity.
81 citations
TL;DR: In this paper, a consistent tanh expansion (CTE) is used to solve the Broer?Kaup (BK) system, and it is proved that the BK system is CTE solvable.
Abstract: A consistent tanh expansion (CTE) is used to solve the Broer?Kaup (BK) system. It is proved that the BK system is CTE solvable. Some exact interaction solutions among different nonlinear excitations such as solitons, rational waves, periodic waves, error function waves and any Burgers waves are explicitly given.
70 citations
TL;DR: In this article, a modified standard model with 48 two-component Weyl fermions was given a non-perturbative definition by embedding the modified model into an SO (10) chiral gauge theory.
Abstract: The standard model is a chiral gauge theory where the gauge fields couple to the right-hand and the left-hand fermions differently. The standard model is defined perturbatively and describes all elementary particles (except gravitons) very well. However, for a long time, we do not know if we can have a non-perturbative definition of the standard model as a Hamiltonian quantum mechanical theory. Here we propose a way to give a modified standard model (with 48 two-component Weyl fermions) a non-perturbative definition by embedding the modified standard model into an SO (10) chiral gauge theory. We show that the SO (10) chiral gauge theory can be put on a lattice (a 3D spatial lattice with a continuous time) if we allow fermions to interact. Such a non-perturbatively defined standard model is a Hamiltonian quantum theory with a finite-dimensional Hilbert space for a finite space volume. More generally, using the defining connection between gauge anomalies and the symmetry-protected topological orders, one can show that any truly anomaly-free chiral gauge theory can be non-perturbatively defined by putting it on a lattice in the same dimension.
70 citations
TL;DR: In this paper, the Debye-Waller factor was used to simulate graphite oxide (GO) diffraction patterns as a function of the displacements of carbon atoms in terms of the Warren-Bodenstein equation.
Abstract: X-ray diffraction patterns of graphite oxide (GO) are theoretically simulated as a function of the displacements of carbon atoms using the Debye—Waller factor in terms of the Warren—Bodenstein equation. The results demonstrate that GO has the turbostratically stacked structure. The high order (00l) peaks gradually disappear with the increase in atomic thermal vibrations along c-axis while the (hk0) ones weaken for the vibrations along a-axis. When the displacement deviation ua = 0.015 nm and uc = 0.100 nm the computed result is consistent with the experimental measurements.
62 citations
TL;DR: In this article, the authors consider the case of a Reissner-Nordstrom AdS black hole with a positive cosmological constant considered as a thermodynamic pressure and its conjugate quantity as thermodynamic volume and find the bounded region of the moduli space allowing the consistency of the model with real thermodynamic variables.
Abstract: We reconsider the study of critical behaviors of Kerr—Newman Anti-de Sitter (AdS) black holes in four dimensions. The study is made in terms of the moduli space parameterized by the charge Q and the rotation parameter a, relating the mass M of the black hole and its angular momentum J via the relation a = J/M. Specifically, we discuss such thermodynamical behaviors in the presence of a positive cosmological constant considered as a thermodynamic pressure and its conjugate quantity as a thermodynamic volume. The equation of state for a charged Reissner—Nordstrom AdS black hole predicts a critical universal number depending on the (Q, a) moduli space. In the vanishing limit of the a parameter, this prediction recovers the usual universal number in four dimensions. Then, we find the bounded region of the moduli space allowing the consistency of the model with real thermodynamical variables.
56 citations
TL;DR: In this article, nonextensive statistics in a blast-wave model are implemented to describe the identified hadron production in relativistic p+p and nucleus-nucleus collisions.
Abstract: Nonextensive statistics in a blast-wave model is implemented to describe the identified hadron production in relativistic p+p and nucleus-nucleus collisions. Incorporating the core and corona components within the TBW formalism allows us to describe simultaneously some of the major observations in hadronic observables at the Relativistic Heavy-Ion Collider (RHIC): the amount of constituent quark scaling (NCQ), the large radial and elliptic flow, the effect of gluon saturation, and the suppression of hadron production at high transverse momentum (pT) due to jet quenching. In this formalism, the NCQ scaling at the RHIC appears as a consequence of a non-equilibrium process. Our study also provides concise reference distributions with a least χ2 fit of the available experimental data for future experiments and models.
55 citations
TL;DR: In this paper, the structural and optical properties of ZnO−CuO nanocomposites were characterized by using various techniques such as UV-vis absorption spectroscopy, photoluminescence, scanning electron microscopy, and energy dispersive x-ray spectrography.
Abstract: Cupric oxide (CuO) nanoparticles were grown on zinc oxide (ZnO) nanorod (NR) arrays to form ZnO−CuO corn-like composites via a simple two step solution-based method. First, ZnO nanorods were grown on a glass substrate by the hydrothermal method. Afterwards, CuO crystals were photochemically deposited on ZnO NRs using ultraviolet (UV) light irradiation at room temperature. The density and size of CuO nanoparticles (NPs) on ZnO NRs can be controlled by the irradiation time of UV light. The structural and optical properties of ZnO−CuO nanocomposites were characterized by using various techniques such as UV-vis absorption spectroscopy, photoluminescence, scanning electron microscopy, energy dispersive x-ray spectroscopy, and x-ray diffraction. ZnO−CuO nanocomposites show an excellent improvement in photocatalytic characteristics compared to bare ZnO NRs.
54 citations
TL;DR: In this paper, a novel radome is presented, which is transparent at operating frequency and is invisible out of band, in order to prevent reflection of the incoming power, frequency selective surfaces loaded with the lumped resistors are employed.
Abstract: A novel radome is presented, which is transparent at operating frequency and is invisible out of band. In order to prevent reflection of the incoming power, frequency selective surfaces loaded with the lumped resistors are employed. To obtain the pass-band properties in lower frequencies, the convoluted slots are utilized. By comparison with the results obtained both by full wave analysis and by the measurements, the performance of the radome is verified. It performs with high transmission characteristics in band, and broadband absorbing properties out of band simultaneously. The oblique incidences are also investigated for both transmission coefficients and reflection ones.
TL;DR: Using the Pekeris approximation, the Schrodinger equation is solved for the nuclear deformed Woods-Saxon potential within the framework of the asymptotic iteration method as mentioned in this paper.
Abstract: Using the Pekeris approximation, the Schrodinger equation is solved for the nuclear deformed Woods—Saxon potential within the framework of the asymptotic iteration method. The energy levels are worked out and the corresponding normalized eigenfunctions are obtained in terms of hypergeometric function.
TL;DR: In this paper, a high efficiency grating coupler between singlemode fiber and silicon-on-insulator waveguide is designed by a formula method, achieving over 78.5% coupling efficiency with 3 dB bandwidth about 50 nm.
Abstract: A high efficiency grating coupler between single-mode fiber and silicon-on-insulator waveguide is designed by a formula method. Over 78.5% coupling efficiency (>−1.05 dB) with 3 dB bandwidth about 50 nm for one grating coupler is obtained experimentally and this result is the highest one as far as we know. This grating coupler is CMOS compatible which needs only one etch-step and is designed for a standard SOI chip without any Bragg reflector or bottom reflector.
TL;DR: In this paper, a high-speed shot-noise-limited balanced homodyne detector is proposed for Gaussian-modulated coherent-state quantum key distribution, where the measurement of quadratures of coherent states is performed by using a homodyn detector.
Abstract: In Gaussian-modulated coherent-state quantum key distribution, the measurement of quadratures of coherent states is performed by using a homodyne detector. However, conventional detectors usually suffer from narrow bands. We present a method to design a high-speed shot-noise-limited balanced homodyne detector. A 300-MHz bandwidth detector is experimentally tested and the level of shot noise is 14 dB higher than the electronic noise. The results show that a detector with this method is potential to design a GHz bandwidth detector for continuous variable quantum key distribution at a low level of ratio of shot noise to electronic noise.
TL;DR: In this article, a new chaotic oscillator based on the realistic model of the HP TiO2 memristor and Chua's circuit is proposed, which has no transient chaos and weak hyper-chaos.
Abstract: We design a new chaotic oscillator based on the realistic model of the HP TiO2 memristor and Chua's circuit. Some basic dynamical behaviors of the oscillator, including equilibrium set, Lyapunov exponent spectrum and bifurcations with respect to various circuit parameters, are investigated theoretically and numerically. Chaotic attractors generated by the proposed oscillator are described with simulations and experiments, showing a good agreement. The main finding by analysis is that the proposed oscillator has no transient chaos and weak hyper-chaos appears. Furthermore, its stability is insensitive to its initial values, thereby generating continuous and stable chaotic oscillation signals for chaos-based applications.
TL;DR: In this paper, the authors combine in-depth neutron diffraction and systematic bulk studies to discover that the √5 × √ 5 Fe vacancy order, with its associated block antiferromagnetic order, is the ground state with varying occupancy ratios of the iron 16i and vacancy 4d sites across the phase-diagram of KxFe2−ySe2.
Abstract: Combining in-depth neutron diffraction and systematic bulk studies, we discover that the √5 × √5 Fe vacancy order, with its associated block antiferromagnetic order, is the ground state with varying occupancy ratios of the iron 16i and vacancy 4d sites across the phase-diagram of KxFe2−ySe2 The orthorhombic order, with one of the four Fe sites vacant, appears only at intermediate temperatures as a competing phase The material experiences an insulator to metal crossover when the √5 × √5 order is highly developed Superconductivity occurs in such a metallic phase
TL;DR: It is pointed 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.
Abstract: 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.
TL;DR: A three-party scheme for remotely sharing a single-qubit operation with Brown state and local operation and classical communication and some discussions are made to show its important features, including determinacy symmetry, security, expansibility and nowaday's experimental feasibility.
Abstract: A three-party scheme for remotely sharing a single-qubit operation with Brown state and local operation and classical communication is proposed. Some discussions are made to show its important features, including determinacy symmetry, security, expansibility and nowaday's experimental feasibility.
TL;DR: The capability of THz imaging for diagnosing human liver cancer is demonstrated by near-field mapping of the absorption constants of liver tissues, which can clearly distinguish cancer from normal tissues fast, automatically, and correctly without pathological H&E staining examination.
Abstract: Based on a room-temperature-operated THz fiber-scanning near-field imaging system, we demonstrate the capability of THz imaging for diagnosing human liver cancer. By THz near-field mapping of the absorption constants of liver tissues, the acquired images can clearly distinguish cancer from normal tissues fast, automatically, and correctly without pathological H&E staining examination. Accordingly, the studied THz imaging system has valuable potential applications in clinical cancer diagnosis. With the help of THz imaging, we can expect to economize the use of hospital and human resources.
TL;DR: In this article, a material with the formula ZrMgMo3O12 having negative thermal expansion is presented and characterized, which is an orthorhombic structure without phase transition or decomposition at least from 123K to 1200K and is not hygroscopic.
Abstract: A material with the formula ZrMgMo3O12 having negative thermal expansion is presented and characterized. It is shown that ZrMgMo3O12 crystallizes in an orthorhombic symmetry with space group Pnma(62) or Pna21(33) and exhibits negative thermal expansion in a large temperature range (αl = −3.8 × 10−6 K−1 from 300K to 1000K by x-ray diffraction and αl = −3.73 × 10−6 K−1 from 295K to 775K by dilatometer). ZrMgMo3O12 remains the orthorhombic structure without phase transition or decomposition at least from 123K to 1200K and is not hygroscopic. These properties make it an excellent material with negative thermal expansion for a variety of applications.
TL;DR: In this paper, the adsorption and diffusion of lithium on silicene were studied by using the first-principles method, and it was found that the energy of Li adsorbing on Silicene is significantly larger than that of Li adaption on graphene.
Abstract: The adsorption and diffusion of lithium on silicene are studied by using the first-principles method. It is found that the adsorption energy of Li adsorbing on silicene is significantly larger than that of Li adsorbing on graphene. With the increasing concentration of adsorbed Li atoms, the adsorption energy also increases. The diffusion barrier of Li on silicene is relatively low, which is insensitive to the concentration of adsorbed atoms.
TL;DR: In this article, an ultrathin Al2O3 film as an insulating layer was deposited onto the CH3NH3PbI3 by atomic layer deposition technology, which significantly enhanced the light-to-electricity conversion efficiency of the devices.
Abstract: Metal-insulator-semiconductor back contact has been employed for a perovskite organic lead iodide heterojunction solar cell, in which an ultrathin Al2O3 film as an insulating layer was deposited onto the CH3NH3PbI3 by atomic layer deposition technology. The light-to-electricity conversion efficiency of the devices is significantly enhanced from 3.30% to 5.07%. Further the impedance spectrum reveals that this insulating layer sustains part of the positive bias applied in the absorber region close to the back contact and decreases the carrier transport barrier, thus promoting transportation of carriers.
TL;DR: In this paper, CdS nanoparticles embedded into polyvinyl alcohol (PVA) films are synthesized by using an in-situ gamma-irradiation-induced method.
Abstract: Monodispersed spherical CdS nanoparticles embedded into polyvinyl alcohol (PVA) films are synthesized by using an in-situ gamma-irradiation-induced method. The formation mechanism of CdS nanoparticles capped by two united cells of PVA is purposed by means of surrounding the CdS nanoparticles with OH bonds of the PVA chain. CdS nanoparticles are found to possess an unusual orthorhombic structure in monoclinic crystalline PVA. The polymer matrix affords protection from agglomeration and controls the particle size. It is found that the distribution of the prepared nanoparticles increases and a narrower size distribution is observed when the gamma radiation is varied from 10 to 50 kGy. While the average size of the nanoparticles is found to be less affected by the variation of the gamma radiation doses. The size range of the synthesized nanoparticles is 14±1 nm. The optical absorption spectra of synthesized CdS nanoparticles in a polymer matrix reveal the blue shift in the band gap energy with respect to CdS bulk materials owing to quantum confinement effect. The photoluminescence study of nanocomposite films shows the green emission arising from the crystalline defects.
TL;DR: In this article, a novel symmetric plasmonic structure consisting of a metal-insulator-metal waveguide and a rectangular cavity is proposed to investigate Fano resonance performance by adjusting the size of the structure.
Abstract: A novel symmetric plasmonic structure consisting of a metal-insulator-metal waveguide and a rectangular cavity is proposed to investigate Fano resonance performance by adjusting the size of the structure. The Fano resonance originates from the interference between a local quadrupolar and a broad spectral line in the rectangular cavity. The tuning of the Fano profile is realized by changing the size of the rectangular cavity. The nanostructure is expected to work as an excellent plasmonic sensor with a high sensitivity of about 530 nm/RIU and a figure of merit of about 650.
TL;DR: This work highlights the importance of studying the effects and performance of recommendation in long-term evolution by studying the influence of recommendation on the evolution of the online bipartite network.
Abstract: We employ a bipartite network to describe an online commercial system Instead of investigating accuracy and diversity in each recommendation, we focus on studying the influence of recommendation on the evolution of the online bipartite network The analysis is based on two benchmark datasets and several well-known recommendation algorithms The structure properties investigated include item degree heterogeneity, clustering coefficient and degree correlation This work highlights the importance of studying the effects and performance of recommendation in long-term evolution
TL;DR: In this article, a fiber-based four-state discrete modulation continuous variable quantum key distribution system based on homodyne detection was proposed, which achieved a secret key rate of 1kbit/s at a transmission distance of 30.2 km.
Abstract: We report a fiber-based four-state discrete modulation continuous variable quantum key distribution system based on homodyne detection. A secret key rate of 1kbit/s is achieved at a transmission distance of 30.2 km. Two factors that result in the excess noises of the quantum key distribution system are analyzed. The first is the relative phase dithering between the signal and local fields, and the second is the local field leakage into the signal field due to the scattering process that depolarizes the local field. It is found that the latter has a significant impact on the excess noise, which is the main limiting factor to the long-distance secure quantum transmission. Some protocols are also given to decrease the excess noise effectively.
TL;DR: In this article, an experimental device is constructed for measuring the density and liquidus temperature of molten fluorides by using the Archimedean and cooling curve methods respectively, and its operation is tested by measuring the densities of NaCl salt.
Abstract: An experimental device is constructed for measuring the density and liquidus temperature of molten fluorides by using the Archimedean and cooling curve methods respectively. Its operation is tested by measuring the density and liquidus temperature of NaCl salt. The accuracy of the liquidus temperature measurement is about +/- 1 K. The density of NaCl measured is in good agreement with the widely recognized data and the deviation is less than 0.2%. The liquidus temperature and density of a typical heat transfer fluoride LiF-NaF-KF (46.5-11.5-42mol%) are investigated.
TL;DR: In this article, the center-of-mass (cm) energy of the non-marginally and marginally bound critical particles in the direct collision and the last stable orbit collision scenarios is obtained.
Abstract: Collision of two general geodesic particles around the Kerr—Newman black hole is studied and the center-of-mass (cm.) energy of the non-marginally and marginally bound critical particles in the direct collision and the last stable orbit collision scenarios is obtained. The constraint conditions that arbitrarily high cm. energy can be obtained for the near-horizon collision of two general geodesic particles in the extremal Kerr—Newman black hole is found, and it is noted that the charge decreases the value of the latitude in which arbitrarily high cm. energy can occur.
TL;DR: In this article, two pairs of new peaks in the XPS spectra involved with the binding energies from Bi 4f and Te 3d electrons correspond to Bi-O-Te bonds.
Abstract: Bi2Te3 films are grown on (111)-oriented GaAs substrates by using the hot wall epitaxy method and the surface oxidation properties in the films are investigated by x-ray photoelectron spectroscopy, Raman spectroscopy, and x-ray diffraction. The results show that the films are c-axis oriented. Two pairs of new peaks in the XPS spectra involved with the binding energies from Bi 4f and Te 3d electrons correspond to Bi—O—Te bonds. Besides the A11g, E2g and A21g vibration modes from Bi2Te3 films, two new peaks at 93.5cm−1 and 123cm−1 are observed in Raman spectra, which are assigned to α-Bi2O3 and TeO2, respectively. Our results are helpful for analyzing the degradation mechanism of topological surface states in Bi2Te3.
TL;DR: In this paper, a ring cavity passively harmonic mode-locked thulium-doped fiber laser (TDFL) using a newly developed single-wall carbon nanotube-based saturable absorber was reported.
Abstract: We report a ring cavity passively harmonic mode-locked thulium-doped fiber laser (TDFL) using a newly developed single-wall carbon nanotube-based saturable absorber. The TDFL generates the 25th harmonic mode-locked stretched pulse train with a high repetition rate of 213 MHz and a pulse duration of 710 fs. The laser operates at 1901.6 nm with an average power of 1.89 mW, which corresponds to the pulse energy of 0.008 nJ, at 1552 nm pump power of 719 mW. The peak-to-background ratio is measured to be 60 dB, which indicates the stability of the laser.