Cluster structure prediction via CALYPSO method
Discovery of superhard materials via CALYPSO methodology
The CALYPSO methodology for structure prediction
Pressure-induced new chemistry
Geoscience material structures prediction via CALYPSO methodology
High-pressure electrides: From design to synthesis
The role of CALYPSO in the discovery of high-Tc hydrogen-rich superconductors
Recent progress on the prediction of two-dimensional materials using CALYPSO
Dynamic and inner-dressing control of four-wave mixing in periodically-driven atomic system
Proof-of-principle experimental demonstration of quantum secure imaging based on quantum key distribution
We present a quantum secure imaging (QSI) scheme based on the phase encoding and weak+vacuum decoy-state BB84 protocol of quantum key distribution (QKD). It allows us to implement a computational ghost imaging (CGI) system with more simplified equipment and reconstructed algorithm by using a digital micro-mirror device (DMD) to preset the specific spatial distribution of the light intensity. What is more, the quantum bit error rate (QBER) and the secure key rate analytical functions of QKD are used to see through the intercept-resend jamming attacks and ensure the authenticity of the imaging information. In the experiment, we obtained the image of the object quickly and efficiently by measuring the signal photon counts with a single-photon detector (SPD), and achieved a secure key rate of 571.0 bps and a secure QBER of 3.99%, which is well below the lower bound of QBER of 14.51%. Besides, our imaging system uses a laser with invisible wavelength of 1550 nm, whose intensity is as low as single-photon, that can realize weak-light imaging and is immune to the stray light or air turbulence, thus it will become a better choice for quantum security radar against intercept-resend jamming attacks.
Numerical investigation on coherent mid-infrared supercontinuum generation in chalcogenide PCFs with near-zero flattened all-normal dispersion profiles
Second-order interference of two independent photons with different spectra
Polymer/silica hybrid waveguide Y-branch power splitter with loss compensation based on NaYF4: Er3+, Yb3+ nanocrystals
A polymer waveguide Y-branch power splitter with loss compensation is proposed based on NaYF4:Er3+, Yb3+ nanocrystals prepared by a high temperature thermal decomposition method. The Y-branch power splitter is designed as a structure of embedded waveguide, and its core material is nanocrystals-doped SU-8. The insertion loss of the device is~15 dB. For an input signal power of 0.05 mW and a pump power of 267.7 mW, the two branches with 5.81-dB and 5.41-dB loss compensations at 1530 nm are achieved respectively. A polymer waveguide Y-branch power splitter with loss compensation has an important research significance.
Properties of multi-Gaussian Schell-model beams carrying an edge dislocation propagating in oceanic turbulence
Extraordinary transmission and reflection in PT-symmetric two-segment-connected triangular optical waveguide networks with perfect and broken integer waveguide length ratios
Low insertion loss silicon-based spatial light modulator with high reflective materials outside Fabry-Perot cavity
The extinction ratio and insertion loss of spatial light modulator are subject to the material problem, thus limiting its applications. One reflection-type silicon-based spatial light modulator with high reflective materials outside the Fabry-Perot cavity is demonstrated in this paper. The reflectivity values of the outside-cavity materials with different film layer numbers are simulated. The reflectivity values of 6-pair Ta2O5/SiO2 films at 1550 nm are experimentally verified to be as high as 99.9%. The surfaces of 6-pair Ta2O5/SiO2 films are smooth:their root-mean-square roughness values are as small as 0.53 nm. The insertion loss of the device at 1550 nm is only 1.2 dB. The high extinction ratio of the device at 1550 nm and 11 V is achieved to be 29.7 dB. The spatial light modulator has a high extinction ratio and low insertion loss for applications.
Multi-objective strategy to optimize dithering technique for high-quality three-dimensional shape measurement
Single event upset on static random access memory devices due to spallation, reactor, and monoenergetic neutrons
This paper presents new neutron-induced single event upset (SEU) data on the SRAM devices with the technology nodes from 40 nm to 500 nm due to spallation, reactor, and monoenergetic neutrons. The SEU effect is investigated as a function of incident neutron energy spectrum, technology node, byte pattern and neutron fluence rate. The experimental data show that the SEU effect mainly depends on the incident neutron spectrum and the technology node, and the SEU sensitivity induced by low-energy neutrons significantly increases with the technology downscaling. Monte-Carlo simulations of nuclear interactions with device architecture are utilized for comparing with the experimental results. This simulation approach allows us to investigate the key parameters of the SEU sensitivity, which are determined by the technology node and supply voltage. The simulation shows that the high-energy neutrons have more nuclear reaction channels to generate more secondary particles which lead to the significant enhancement of the SEU cross-sections, and thus revealing the physical mechanism for SEU sensitivity to the incident neutron spectrum.
Theoretical framework for geoacoustic inversion by adjoint method
Evolution of real contact area during stick-slip movement observed by total reflection method
Stabilized seventh-order dissipative compact scheme for two-dimensional Euler equations
Numerical simulation on dynamic behaviors of bubbles flowing through bifurcate T-junction in microfluidic device
Construction of an Hα diagnostic system and its application to determine neutral hydrogen densities on the Keda Torus eXperiment
A 10-channel Hα diagnostic system has been designed with the rapid response rate of 300 kHz, spatial resolution of about 40 mm, and overlap between adjacent channels of about 3%, and it has been implemented successfully on Keda Torus eXperiment (KTX), a newly constructed, reversed field pinch (RFP) experimental device at the University of Science and Technology of China (USTC). This diagnostic system is a very important tool for the initial KTX operations. It is compact, with an aperture slit replacing the traditional optical lens system. A flexural interference filter is designed to prevent the center wavelength from shifting too much as the increase of angle from vertical incidence. To eliminate the stray light, the interior of the system is covered with the black aluminum foil having a very high absorptivity. Using the Hα emission data, together with the profiles of electron temperature and density obtained from the Langmuir probe, the neutral density profiles have been calculated for KTX plasmas. The rapid response rate and good spatial resolution of this Hα diagnostic system will be beneficial for many studies in RFP plasma physics.
The inverse Bremsstrahlung absorption in the presence of Maxwellian and non-Maxwellian electrons
Defects and electrical properties in Al-implanted 4H-SiC after activation annealing
First principles study of interactions of oxygen-carbon-vacancy in bcc Fe
Physical properties of ternary thallium chalcogenes Tl2MQ3 (M=Zr, Hf; Q=S, Se, Te) via ab-initio calculations
Phosphine-free synthesis of FeTe2 nanoparticles and self-assembly into tree-like nanoarchitectures
Expansion dynamics of a spherical Bose-Einstein condensate
We experimentally and theoretically observe the expansion behaviors of a spherical Bose-Einstein condensate. A rubidium condensate is produced in an isotropic optical dipole trap with an asphericity of 0.037. We measure the variation of the condensate size in the expansion process after switching off the trap. The free expansion of the condensate is isotropic, which is different from that of the condensate usually produced in the anisotropic trap. We derive an analytic solution of the expansion behavior based on the spherical symmetry, allowing a quantitative comparison with the experimental measurement. The interaction energy of the condensate is gradually converted into the kinetic energy during the expansion and after a long time the kinetic energy saturates at a constant value. We obtain the interaction energy of the condensate in the trap by probing the long-time expansion velocity, which agrees with the theoretical calculation. This work paves a way to explore novel quantum states of ultracold gases with the spherical symmetry.
Highly reliable and selective ethanol sensor based on α-Fe2O3 nanorhombs working in realistic environments
A highly reliable and selective ethanol gas sensor working in realistic environments based on alpha-Fe2O3 (α-Fe2O3) nanorhombs is developed. The sensor is fabricated by integrating α-Fe2O3 nanorhombs onto a low power microheater based on micro-electro-mechanical systems (MEMS) technology. The α-Fe2O3 nanorhombs, prepared via a solvothermal method, is characterized by transmission electron microscopy (TEM), Raman spectroscopy, x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS). The sensing performances of the α-Fe2O3 sensor to various toxic gases are investigated. The optimum sensing temperature is found to be about 280 ℃. The sensor shows excellent selectivity to ethanol. For various ethanol concentrations (1 ppm-20 ppm), the response and recovery times are around 3 s and 15 s at the working temperature of 280 ℃, respectively. Specifically, the α-Fe2O3 sensor exhibits a response shift less than 6% to ethanol at 280 ℃ when the relative humidity (RH) increases from 30% to 70%. The good tolerance to humidity variation makes the sensor suitable for reliable applications in Internet of Things (IoT) in realistic environments. In addition, the sensor shows great long-term repeatability and stability towards ethanol. A possible gas sensing mechanism is proposed.
Electronic properties of size-dependent MoTe2/WTe2 heterostructure
Lateral two-dimensional (2D) heterostructures have opened up unprecedented opportunities in modern electronic device and material science. In this work, electronic properties of size-dependent MoTe2/WTe2 lateral heterostructures (LHSs) are investigated through the first-principles density functional calculations. The constructed periodic multi-interfaces patterns can also be defined as superlattice structures. Consequently, the direct band gap character remains in all considered LHSs without any external modulation, while the gap size changes within little difference range with the building blocks increasing due to the perfect lattice matching. The location of the conduction band minimum (CBM) and the valence band maximum (VBM) will change from P-point to Γ-point when m plus n is a multiple of 3 for A-mn LHSs as a result of Brillouin zone folding. The bandgap located at high symmetry Γ-point is favourable to electron transition, which might be useful to optoelectronic device and could be achieved by band engineering. Type-Ⅱ band alignment occurs in the MoTe2/WTe2 LHSs, for electrons and holes are separated on the opposite domains, which would reduce the recombination rate of the charge carriers and facilitate the quantum efficiency. Moreover, external biaxial strain leads to efficient bandgap engineering. MoTe2/WTe2 LHSs could serve as potential candidate materials for next-generation electronic devices.
Hubbard model on an anisotropic checkerboard lattice at finite temperatures: Magnetic and metal-insulator transitions
We study magnetic and Mott transitions of the Hubbard model on the geometrically frustrated anisotropic checkerboard lattice at half filling using cellular dynamical mean-field theory. Phase diagrams over a wide area of the parameter space are obtained by varying the interparticle interaction strength, geometric frustration strength, and temperature. Our results show that frustration and thermal fluctuations play a competing role against the interactions and in general favor a metallic phase without antiferromagnetic order. Due to their interplay, the system exhibits competition between antiferromagnetic insulator, antiferromagnetic metal, paramagnetic insulator, and paramagnetic metal phases in the intermediate-interaction regime. In the strong-interaction limit, which reduces to the Heisenberg model, our result is consistent with previous studies.
Negative transconductance effect in p-GaN gate AlGaN/GaN HEMTs by traps in unintentionally doped GaN buffer layer
Optical response of an inverted InAs/GaSb quantum well in an in-plane magnetic field
The optical response of an inverted InAs/GaSb quantum well is studied theoretically. The influence of an in-plane magnetic field that is applied parallel to the quantum well is considered. This in-plane magnetic field will induce a dynamical polarization even when the electric field component of the external optical field is parallel to the quantum well. The electron-electron interaction in the quantum well system will lead to the de-polarization effect. This effect is found to be important and is taken into account in the calculation of the optical response. It is found that the main feature in the frequency dependence of the velocity-velocity correlation function remains when the velocity considered is parallel to the in-plane magnetic field. When the direction of the velocity is perpendicular to the in-plane magnetic field, the de-polarization effect will suppress the oscillatory behavior in the corresponding velocity-velocity correlation function. The in-plane magnetic field can change the band structure of the quantum well drastically from a gapped semiconductor to a no-gapped semi-metal, but it is found that the distribution of the velocity matrix elements or the optical transition matrix elements in the wave vector space has the same two-tadpole topology.
Observation of hopping transitions for delocalized electrons by temperature-dependent conductance in siliconjunctionless nanowire transistors
We demonstrate transitions of hopping behaviors for delocalized electrons through the discrete dopant-induced quantum dots in n-doped silicon junctionless nanowire transistors by the temperature-dependent conductance characteristics. There are two obvious transition platforms within the critical temperature regimes for the experimental conductance data, which are extracted from the unified transfer characteristics for different temperatures at the gate voltage positions of the initial transconductance gm peak in Vg1 and valley in Vg2. The crossover temperatures of the electron hopping behaviors are analytically determined by the temperature-dependent conductance at the gate voltages Vg1 and Vg2. This finding provides essential evidence for the hopping electron behaviors under the influence of thermal activation and long-range Coulomb interaction.
Enhanced spin-dependent thermopower in a double-quantum-dot sandwiched between two-dimensional electron gases
Magnetic vortex gyration mediated by point-contact position
Cascaded plasmonic nanorod antenna for large broadband local electric field enhancement
We propose a cascaded plasmonic nanorod antenna for large broadband electric near-field enhancement. The structure has one big gold nanorod on each side of a small two-wire antenna which consists of two small gold nanorods. For each small nanorod, the enhanced and broadened optical response can be obtained due to the efficient energy transfer from its adjacent big nanorod through strong plasmonic near-field coupling. Thus, the electric field intensity of the cascaded antenna is significantly larger and broader than that of the individual small two-wire antenna. The resonant position, field intensity enhancement, and spectral width of the cascaded antenna are highly tunable by varying the geometry of the system. The quantum efficiency of the cascaded antenna is also greatly enhanced compared with that of the small antenna. Our results are important for the applications in field-enhanced spectroscopy.
Photoluminescence properties of blue and green multiple InGaN/GaN quantum wells
Effect of AlN coating on hydrogen permeability and surface structure of VT6 alloy by vacuum arc ion plating
Effect of sintering temperature on luminescence properties of borosilicate matrix blue-green emitting color conversion glass ceramics
Flexible rGO/Fe3O4 NPs/polyurethane film with excellent electromagnetic properties
Parameter identification and state-of-charge estimation approach for enhanced lithium-ion battery equivalent circuit model considering influence of ambient temperatures
Analysis of non-uniform hetero-gate-dielectric dual-material control gate TFET for suppressing ambipolar nature and improving radio-frequency performance
Opto-electromechanically induced transparency in a hybrid opto-electromechanical system
Designing of spin filter devices based on zigzag zinc oxide nanoribbon modified by edge defect
Quantitative heterogeneity and subgroup classification based on motility of breast cancer cells
Cancer cell motility and its heterogeneity play an important role in metastasis, which is responsible for death of 90% of cancer patients. Here, in combination with a microfluidic technique, single-cell tracking, and systematic motility analysis, we present a rapid and quantitative approach to judge the motility heterogeneity of breast cancer cells MDA-MB-231 and MCF-7 in a well-defined three-dimensional (3D) microenvironment with controllable conditions. Following this approach, identification of highly mobile active cells in a medium with epithelial growth factor will provide a practical tool for cell invasion and metastasis investigation of multiple cancer cell types, including primary cells. Further, this approach could potentially become a speedy (~hours) and efficient tool for basic and clinical diagnosis.
Theory and method of dual-energy x-ray grating phase-contrast imaging
Benefit community promotes evolution of cooperation in prisoners' dilemma game
Theoretical analyses of stock correlations affected by subprime crisis and total assets: Network properties and corresponding physical mechanisms