Physics Open最新文献

The two types of cooperative effects between the converted photons in the multiple steps of Raman lasing are proposed. The first type involves the cooperative process between the photons of one of the steps of Raman conversion. The second cooperative effect appears between the photons belonging to different steps of multiple conversions. This new type of generated coherent state is proposed by novel bimodal entangled sources, which take into consideration both the coherence and collective phenomena between the photons belonging to the system of the bimodal field obtained in multiple Raman emissions. For this, the creation and annihilation operators of the new resonator quasi-particle ware introduced taking into consideration the Hilbert space of field vectors at frequency differences, ${\omega }_{p+1}-{\omega }_p$ between the anti-Stokes components of multiple Raman lasing. The application of higher-order multiple Roman bimodal coherent field quantum information is described in accordance with the definition of quantum amplitude and phase of such entangled states of light. The cooperative properties of the bimodal field in the multiple scattering processes of Raman lasing in the cavity/fiber and its interaction with ensemble of atoms prepared in coherent state are proposed. We introduced the new characteristics of bi-modes field in which the multiple Raman scattering takes into consideration the interaction with coherent excitation and non-stationary quantum fluctuations of the generation rate of the introduced quasi particles. Here, we represent the rate moments through the annihilation and generation operators of the cavity quasi-parties.

We investigate the pressure effect on Li₄OX₂ (X = Cl, Br, and I) for the first time using DFT simulation. Li₄OCl₂ shows mechanical stability up to 8 GPa, whereas Li₄OBr₂ has stability up to 30 GPa pressure according to the Born stability criteria. In contrast, Li₄Ol₂ becomes unstable above 3.0 GPa pressure. Hence, anomalies were observed for Li₄OX₂ (X = Cl, Br, and I) solid electrolyte for elastic parameters, C_ij under pressure study. The elastic moduli are isotropic in the xy plane, conversely, along the xz and yz plane anisotropic behavior is observed. There is a band gap that exists at zero temperature and pressure. The contribution at the fermi level mainly comes from the O 2p states. The highest reflectivity (∼98 %) was observed for Li₄OCl₂ at ∼ 17 eV in the IR-visible-UV region showing that this material under study may be considered as a potential coating material to avoid solar heating. The smaller value of the volume thermal expansion coefficient for Li₄OCl₂ indicates stronger atomic bonding exists, which was also observed from the elastic parameter analysis.

To produce high crystalline and unified cuprite nano single crystals from copper sulfate pentahydrate a unique bi-polarized methanol-water mixture reduces surface energy and enhances capping efficiency. Exhaustive significance lattice parameters, crystal volume, peak profiling, lattice constant, percent of crystallinity and crystal strain were analyzed by the whole powder pattern fitting (WFPP) Rietveld refinement method. A red shift at 636.0 nm in UV spectrophotometry is associated with a high surface plasmon effect and the zeta potential of 89.0 mV confirms the excellent stability of the cuprite crystal. Crystallographic data, d-spacing 0.25188 nm, lattice parameters a = b = c = 3.78 Å, α = β = γ = 90° of cuprite single crystal was further established by the selected area electron diffraction (SAED) in TEM. Energy dispersive spectroscopy (EDS) reveals the formation of the 100.0 % unified cuprite single crystal.

Inertial sensors that measure the acceleration of ultracold atoms promise unrivalled accuracy compared to classical equivalents. However, atomic systems are sensitive to various perturbations, including magnetic fields, which can introduce measurement inaccuracies. To address this challenge, we have designed, manufactured, and validated a magnetic field stabilisation system for a quantum sensor based on atom interferometry. We solve for the magnetic field generated by surface currents in-between a pair of bi-rectangular coils and approximate the surface current using discrete wires. The wires are wound by-hand onto machined panels which are retrofitted onto the existing mounting structure of the sensor without interfering with any experimental components. Along the central $60\mathrm{mm}$ of the $y$-axis, which aligns with the trajectory of the atoms during interferometry, the coils are measured to generate an independent uniform axial magnetic field with a strength of $B_z=\left(22.81\pm 0.01\right)$ $\mu$T/A [$\mathrm{mean}\pm 2\sigma \mathrm{std.\; error}$] and an independent linear axial field gradient of strength $d{B}_z/dy=\left(10.6\pm 0.1\right)$ $\mu$T/Am. The uniform $B_z$ field is measured to deviate by a maximum value of 1.3% in the same region, which is a factor of three times more uniform than the previously-used on-sensor rectangular $B_z$ compensation set.

Using auto-combustion approach, cobalt ferrite nanoparticles doped with Zn⁺² with the basic chemical composition Zn_xCo_1-xFe₂O₄ (x = 0 to 1: in steps of 0.25) were prepared. Phase confirmation of the proposed samples was confirmed through XRD studies. XRD pattern of the calcined ferrites revealed single phase spinel cubic structure. At room temperature, using HIOKI LCR meter (Model no: 3520-50) the dielectric measurements in the frequency range 10² Hz–10⁶ Hz were performed. Dielectric constant (ε′) and dielectric loss tangent (tan δ) of synthesized nano-materials were investigated as a function of frequency and Zn⁺² concentration at ambient temperature and all the samples exhibited dielectric dispersion. Magnetic measurements for Zn_xCo_1-xFe₂O₄ nano-ferrites were carried out at room temperature using a vibrating sample magnetometer (VSM), and all the samples of the system CoZnFe₂O₄ exhibited ferromagnetic behavior.

The Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃/BaTiO₃ and Ba_0.7Ca_0.3TiO₃/BaZr_0.2Ti_0.8O₃ bilayer ceramics are fabricated via a solid-state sintering method. The phase, microstructure, and chemical composition of the bilayer ceramics are compared with pure ceramics, i.e., BaTiO₃ (BT), Ba_0.85Ca_0.15Zr_0.1Ti_0.9O₃ (BCZT), Ba_0.7Ca_0.3TiO₃ (BCT), and BaZr_0.2Ti_0.8O₃ (BZT). The crystal structure of both bilayer ceramics did not differ from that of each pure ceramic. The bilayer structure has a good interface bonding between each layer. The bilayer ceramics have two-phase transition temperatures, which come from BCZT and BT for the BCZT/BT system and BCT and BZT for the BCT/BZT system. Compared with pure ceramic, the interface causes a decrease in ε_m of the bilayer ceramics. The difference between the maximum polarization and remanent polarization (ΔP) has an essential role in improving the energy storage efficiency of these ceramics. The results suggest modification in the ceramic's dielectric and energy storage efficiency by bilayer structure.

This report presents investigation on influence of pH on growth, structural, thermal, linear and nonlinear optical properties of _L-asparagine monohydrate (LAM) single crystal for the first time. Single crystals of LAM were grown at different pH by solution growth method by allowing slow evaporation of solvent. Crystal grown at pH 6.4 grows slowly as compare to other crystals grown at other pH values. The slight variation in lattice parameters of grown crystals has been confirmed by powder X-ray diffraction study. FT-IR study confirms the presence of functional groups of LAM in all grown crystals. Influence of pH on optical quality of crystals has been discussed. The crystal grown at pH 5.4 has maximum optical transparency and shows 2 and 20 % more transmission than crystals grown at pH 4.4 and 6.4, respectively. Other optical parameters like cutoff wavelength (λ_max), band gap (E_g), linear refractive index (n), reflectance, extinction coefficient (k), electrical susceptibility (χ), optical conductivity(σ_op), electrical conductivity (σ_el) and Urbach energy (E_u) of all crystals have been evaluated from transmission data. The LAM crystal grown at pH 6.4 show high values of third order nonlinear optical parameters, as compare to other grown crystals, that attest its suitability for applications like higher harmonic generation, optical switching, optical limiting and other photonic applications over other grown crystals. Thermal stability of the grown crystals has been attested by TG-DTA study.

This study presents an efficient method to convert methane into valuable olefins using a Solid Oxide Fuel Cell (SOFC) membrane reactor. Methane, abundant in natural and shale gas, serves as a sustainable feedstock due to its favorable carbon-hydrogen ratio. The SOFC membrane reactor eliminates costly air separation units and safety risks associated with explosive methane-oxygen mixtures. A planar SOFC stack achieves over 30 % methane conversion, 40 % ethylene selectivity, and power generation capabilities. Optimization with mixed-conducting ceramics enhances electrical performance without compromising catalytic activity. The stack's scalability is demonstrated, with the 5-cell configuration surpassing the 2-cell setup. This innovative approach offers a sustainable solution to methane waste, producing high-value chemicals while reducing environmental impact.

This work investigates the behavior of Shannon entropy and Fisher information for the Varshni-Hellmann potential (VHP) in one and three dimensions using the Nikiforov-Uvarov method. We employ the Greene-Aldrich approximation scheme to obtain the energy eigenvalues and normalized wavefunctions, which are then used to calculate these information-theoretic quantities. Our analysis revealed remarkably similar high-order features in both position and momentum spaces. Notably, our calculations showed enhanced accuracy in predicting particle localization within position space. Furthermore, the combined position and momentum entropies obeyed the lower and upper bounds established by the Berkner-Bialynicki-Birula-Mycieslki inequality. Additionally, for three-dimensional systems, the Stam-Cramer-Rao inequalities were fulfilled for different eigenstates with respect to the calculated Fisher information. It is observed that as the position Fisher entropy decreases, indicating a more precise measurement of position, the momentum Fisher entropy must increase. This implies that the Fisher information regarding momentum decreases, resulting in a decrease in the precision of momentum measurement. This demonstrates how position and momentum uncertainties complement each other in quantum mechanics. Exploring the balance between position and momentum Fisher entropy reveals a fundamental aspect of the uncertainty principle in quantum mechanics, highlighting the restrictions on measuring certain pairs of conjugate variables simultaneously with high precision.

In this study, an attempt has been made to explore the physical characteristics of Sc₂Al₂C₃, including a first-time investigation of elastic anisotropy, thermodynamic, and optical properties. The physical properties of other Sc-Al-C systems have also been compared. The elastic constants and phonon dispersion curves confirmed the mechanical and dynamical stabilities of Sc₂Al₂C₃, and the estimated lattice parameters agreed well with the experimental results. The semiconducting behavior of Sc₂Al₂C₃ has been confirmed by band structure and density of states calculations. An in-depth discussion is presented on the melting point, minimum thermal conductivity, and the Debye temperature. The Helmholtz free energy (F), internal energy (E), entropy (S), and specific heat capacity (C_v) are also computed from the phonon density of states. The dielectric constant, refractive index, absorption coefficient, photoconductivity, reflectivity, and loss function have also been calculated for the first time. Band structure calculations and optical parameters complement each other very well.