Suppression of DC term in Fresnel digital holography by sequence subtraction of holograms

An experimental method for suppression of DC term in the reconstructed images from Fresnel digital holograms is presented. In this method, two holograms for the same object are captured sequentially and subtracted. Since these two holograms are captured at different moments, they are slightly different from each other for fluctuations of noises. The DC term is suppressed in the image reconstructed from the subtraction hologram, while the two virtual and real images are successfully reconstructed. This method can be potentially used for the improvement of image quality reconstructed from Fresnel digital holograms

Ionic Diffusion and Electronic Transport in Eldfellite Nax_xFe(SO4_4)2_2

Discovering new electrodes for sodium-ion battery requires clear understanding of the material process during battery operation. Using first-principles calculations, we identify mechanisms of ionic diffusion and electronic transfer in newly developed cathode material, eldfellite Na$_x$Fe(SO$_4$)$_2$, reproducing the electrochemical properties in good agreement with experiment. The inserted sodium atom is suggested to diffuse along the two-dimensional pathway with preceding movement of the host sodium atom, and the activation energy is calculated to be reasonable for fast insertion. We calculate the electronic properties, showing the band insulating at low composition of inserted sodium, for which the electron polaron formation and hoping are also suggested. Our results may contribute to opening a new way of developing innovative cathode materials based on iron and sulfate ion

Revealing the formation and electrochemical properties of bis(trifluoromethanesulfonyl) imide intercalated graphite with first-principles calculations

Graphite has been reported to have anion as well as cation intercalation capacities as both cathode and anode host materials for the dual ion battery. In this work, we study the intercalation of bis(trifluoromethanesulfonyl) imide (TFSI) anion from ionic liquid electrolyte into graphite with first-principles calculations. We build models for TFSI-C$_n$ compounds with systematically increasing unit cell sizes of graphene sheet and investigate their stabilities by calculating the formation energy, resulting in the linear decrease and arriving at the limit of stability. With identified unit cell sizes for stable compound formation, we reveal that the interlayer distance and relative volume expansion ratio of TFSI-C$_n$ increase as increasing the concentration of TFSI intercalate during the charge process. The electrode voltage is determined to be ranged from 3.8 V to 3.0 V at the specific capacity ranging from 30 mAh g$^{-1}$ to 54 mAh g$^{-1}$ in agreement with experiment. Moreover, a very low activation barrier of under 50 meV for TFSI migration and good electronic conductivity give a proof of using these compounds as a promising cathode. Through the analysis of charge transfer, we clarify the mechanism of TFSI-C$_n$ formation, and reveal new prospects for developing graphite based cathode

New discrete method for investigating the response properties in finite electric field

In this paper we develop a new discrete method for calculating the dielectric tensor and Born effective charge tensor in finite electric field by using Berry's phase and the gauge invariance. We present a new method to overcome non-periodicity of the potential in finite electric field due to the gauge invariance, and construct the dielectric tensor and Born effective charge tensor that satisfy translational symmetry in finite electric field. In order to demonstrate the correctness of this method, we also perform calculations for the semiconductors AlAs and GaAs under the finite electric field to compare with the preceding method and the experiment.Comment: arXiv admin note: text overlap with arXiv:cond-mat/0612442 by other author

Exciton-Plasmon Coupling Effects on the Nonlinear Optical Susceptibility of Hybrid Quantum Dot-Metallic Nanoparticle System

We have studied theoretically the exciton-plasmon coupling effects on the third-order optical nonlinearity of a coherently coupled hybrid system of a metal nanoparticle and a semiconductor quantum dot in the presence of a strong control field with a weak probe field

Two-dimensional hybrid composites of SnS2 with graphene and graphene oxide for improving sodium storage: A first-principles study

Among the recent achievements of sodium-ion battery (SIB) electrode materials, hybridization of two-dimentional (2D) materials is one of the most interesting appointments. In this work, we propose to use the 2D hybrid composites of SnS2 with graphene or graphene oxide (GO) layers as SIB anode, based on the first-principles calculations of their atomic structures, sodium intercalation energetics and electronic properties. The calculations reveal that graphene or GO film can effectively support not only the stable formation of hetero-interface with the SnS2 layer but also the easy intercalation of sodium atom with low migration energy and acceptable low volume change. The electronic charge density differences and the local density of state indicate that the electrons are transferred from the graphene or GO layer to the SnS2 layer, facilitating the formation of hetero-interface and improving the electronic conductance of the semiconducting SnS2 layer. These 2D hybrid composites of SnS2/G or GO are concluded to be more promising candidates for SIB anodes compared with the individual monolayers

Influence of Pulse width and Rabi frequency on the Population dynamics of three-level system in two-photon absorption process

We investigate the population dynamics of the three-level system in the two-photon absorption (TPA) process, mainly focusing the influence of pulse width and Rabi frequency on the population dynamics of the system. We observe the dependency of the population with the Rabi frequency and the pulse width. We also show that the arbitrary superposition state consisted in two states, upper state and lower state, is possible by controlling the pulse width and Rabi frequency. The results obtained can be used to the case of more complex multilevel system and they can be valuable for coherent quantum control in quantum information processing.Comment: arXiv admin note: text overlap with arXiv:quant-ph/0402155 by other authors without attributio

Study on the Vibration Displacement Distribution of a Circular Ultrasonic Motor Stator

In this paper is presented a theoretical consideration on the stator's displacement distribution, which is one of the most important problems in defining the structure of the circular ultrasonic motor stator. The results are compared with results obtained utilizing holographic interferometer, laser vibrometer and a FEM (finite element method) simulation. They are in a good agreement with each other

Control of the Optical Response of an Artificial Hybrid Nanosystem Due to the Plasmon-Exciton Plasmon Coupling Effect

The optical response of an artificial hybrid molecule system composed of two metallic nanoparticles (MNPs) and a semiconductor quantum dot (SQD) is investigated theoretically due to the plasmon-exciton-plasmon coupling effects on the absorption properties of the hybrid nanosystem, which depends on the interaction between the induced dipole moments in the SQD and the MNPs, respectively. We show that the strong coupling of exciton and localized surface plasmons in such a hybrid molecules leads to appealing, tunable optical properties by adjusting the symmetry of the hybrid molecule nanosystem with controllable interparticle distances. We also address here the influence of the size of the MNPs and dielectric constant of the background medium on the optical absorption of the MNPs and SQD, respectively, which results in the interparticle Foster resonance energy transfer (FRET). Our results will open an avenue to deal with the surface-enhanced spectroscopies and potential application of the quantum information

Apparent Positions of Planets

The apparent positions of planets are determined by means of the fundamental ephemerides, the precession-nutation models of the Earth, the gravitational effects and aberrations et al. Around 2000, many astrometrical conceptions, models and theories had been newly defined and updated:for the fiducial celestial reference system, the ICRS is introduced, the fundamental ephemerides - DE405/LE405 et al.,precession-nutation model - IAU 2000A/IAU 2006 model. Using the traditional algorithm and the updated models, we develop the system of calculating the apparent positions of planets. The results are compared with the Astronomical Almanac and proved in their correctness.Comment: 9 pages, 3 figure