Iranian Journal of Applied Physics
https://jap.alzahra.ac.ir/
Iranian Journal of Applied Physicsendaily1Wed, 20 Mar 2024 00:00:00 +0330Wed, 20 Mar 2024 00:00:00 +0330Research Paper: Investigation of Thermoelectric, Dynamical, Electron and Optical Properties of C3N Monolayer Using First Principles Calculations
https://jap.alzahra.ac.ir/article_7401.html
In this paper, the thermo-electric, phonon, electronic, and optical properties of the C3N monolayer have been investigated using the Wien2K computational code based on first principles calculations in the framework of the density functional theory. The study of electronic properties shows the behavior of non-magnetic semiconductors with an indirect gap with a value of 0.5 electron volts for this two-dimensional structure. Also, optical properties such as dielectric function, reflection, energy loss function, absorption coefficient, and optical conductivity are calculated. C3N monolayer is optically anisotropic in z and x direction, which according to the refractive index diagram leads to birefringence, which is a key parameter for this compound's linear optical performance. The results provide a fundamental understanding of the design of composite structures used in nanodevices based on two-dimensional advanced materials. The linear response approach along the symmetric points calculates the phonon dispersion diagram. The results indicate the absence of negative modes in the phonon spectrum, indicating that the structure is dynamically stable. Investigating the thermoelectric properties of the C3N monolayer using the semi-classical Boltzmann theory shows that this monolayer has a value coefficient (ZT) close to one at room temperature and temperatures lower than room temperature. As a result, it can be proposed as a candidate for thermoelectric applications.Research Paper: Temperature Effect on the Hybrid Electron Spin- oscillation Entanglement in an Anisotropic Two- dimensional Quantum Dot
https://jap.alzahra.ac.ir/article_7522.html
Entanglement plays a fundamental role in the field of quantum computing and quantum communication. In real conditions, a physical system is never isolated and inevitably interacts with its surroundings. Temperature is one of these effects that mainly reduces entanglement. In real conditions, the system is at a non-zero temperature, which will lead to a mixed state. Therefore, in the present work, the combined thermal entanglement of electron spin-oscillation in an anisotropic two-dimensional quantum dot is investigated using the negativity criterion. The results show that the combined entanglements are strongly dependent on the changes of the controllable parameters, such as the Rashba parameter and the magnetic field. The thermal entanglement between the spin and the assembly of oscillators is zero at absolute zero temperature and reaches a maximum with increasing temperature and then tends to zero asymptotically. This temperature, at which the amount of entanglement reaches its maximum value, can be controlled by changing the magnetic field and the coupling of the Rashba parameter. These two factors also control the rate of reaching the asymptotic state. These results provide a way to control the degree of entanglement between electron degrees of freedom, which is a fundamental requirement of quantum information processing.Research Paper: Investigating the Effect of Environmental Temperature on the Phenomenon of Gene Transcription: Lyapunov Exponent
https://jap.alzahra.ac.ir/article_7523.html
Gene expression is known as a phenomenon that shapes human life. This very complex phenomenon is formed from two stages: transcription and translation. In this study, we used the Nose-Hoover thermostat to model the effect of ambient temperature on gene expression since temperature regulates the biological clock of living systems. We have used the Lyapunov exponent approach to investigate the effect of control parameters on gene expression, including the degradation rates of messenger RNA and proteins, and to find critical points (phenomenon boundary limits), mRNA, and protein level boundary values. The rate of degradation in the process of protein synthesis has been investigated with the help of the Lyapunov exponent approach. According to this study, the optimal temperature for the production of mRNA molecules by Escherichia coli bacteria is 306 Kelvin. The study also used the chaos approach to show that the faster the mRNA molecules are degraded, the more they are transcribed, and the more chaotic the system becomes.Research Paper: Reflection of Ultra-Short Light Pulses in Multilayer Dielectric Structures and Micro-resonators by FDTD Method
https://jap.alzahra.ac.ir/article_7456.html
In the last two decades, photonic crystals and structures that are based on them (photonic structures) have been examined and have been widely utilized in various optical applications. In this article, a theoretical and numerical model for the propagation of electromagnetic waves in multilayer dielectric structures is developed. The propagation of ultra-short light pulses in multilayer media and microresonators is investigated, and the energy reflection and transmission coefficients depending on the parameters of the environment and duration of the optical pulse are calculated. A method for calculating the transmission and reflection spectra of one-dimensional photonic crystal based on FDTD modeling with the emission of ultra-short optical pulses is proposed. To calculate the transmission and reflection spectrum of a one-dimensional photonic crystal and to simulate the propagation of ultra-short light pulses, in multilayer dielectric structures and microresonators, based on the numerical solution of Maxwell's equations with the finite difference approximation in the space-time domain, is performed.Research Paper: Investigation of Laser Self-Focusing in Quantum Plasma by the Moment Theory Approach
https://jap.alzahra.ac.ir/article_7295.html
In this work, considering the moment theory propagation of the laser beam with relativistic intensity in thermal quantum plasma is studied. Using the Maxwell equation and dielectric function obtained by the quantum hydrodynamic model, the mathematical equation for the laser beam width parameter is achieved and solved numerically by the fourth-order Runge-Kutta method. The results show that the stronger self-focusing effect is found in the moment theory compared to paraxial approximation. Also, similar to paraxial approximation, with growing Fermi temperature, plasma density and laser intensity, the oscillation frequency of the beam width parameter increases and focusing length decreases which means improving the self-focusing effect. Furthermore, it is seen that behaviors of the critical radius are not similar in the two theories, as in the moment theory, with increasing laser intensity, critical radius decreases until it becomes independent of the beam intensity, but in the paraxial approximation, the critical radius after a minimum value is enhanced with increasing laser intensity.Research Paper: Non-Classicality Indicators of Entangled and Squeezed Number States
https://jap.alzahra.ac.ir/article_7378.html
Many non-classicality indicators are used to measure the quantum effects of different systems. Kenfack's and Sadeghi's non-classicality indicators are introduced regarding the amount of Wigner distribution function's negativities and interferences in phase space quantum mechanics, respectively. Kenfack&rsquo;s non-classicality indicator is used for cases just in the Wigner representation, whereas Sadeghi&rsquo;s non-classicality indicator is effectively, applied for some real distribution functions. In this paper, we investigate these non-classicality indicators for the entangled photon number states in the Wigner, Husimi, and Rivier representations. It is shown that for a two-level entangled state, Sadeghi's indicator has more benefits to measure entanglement with respect to Kenfack's indicator. For the two-level entangled state, we also show a correspondence between Sadeghi's non-classicality indicator and the Von Neumann entropy. It is also shown that for the superposition of the squeezed number state and ground number state, the squeezing parameter affects the entanglement feature and Sadeghi's non-classicality indicator increases with the increase of the squeezing parameter.Research Paper: The analysis of Governing Thermodynamics of Plasma Waste Incinerator, Temperature Measurement and Analysis of Burning Chamber and Calculation of Electrical Arc Temperature
https://jap.alzahra.ac.ir/article_7399.html
Using the experimental results and data, the thermodynamic characteristics and thermal analysis of the electrical arc of torch electrodes and energy deposition in the waste-incinerator primary designed chamber were investigated. The temperature of arc in the intermediate electrode which is called the float nozzle was measured at 7000-8000 Kelvin based on the input power of 2 kW. The plasma plume temperature implied to be lower than the arc temperature according to the cold gas flow in the nozzle. The efficiency of energy transferring to the plasma plume is dependent on the geometrical electrode and nozzle design, and gas flow rate. After ten seconds, the chamber temperature was measured at 1193 Kelvin by thermocouple with the performance of electrical elements and plasma torch. The chamber temperature increasing in an adiabatic process was calculated at 1230 Kelvin after this time. According to the isothermal approach, the heat flow rate, and conduction loss calculation, the chamber temperature was obtained at about 900-1000 Kelvin. Using two approaches with inevitable approximations, the calculated temperature ranges for arc and plasma plume energy estimation have reasonable compatibility and this led to the road map of optimization and development for future torch planning and waste-incinerator chamber design.Research Paper: Calculation of Surface Plasmons of Two Closely Metallic Nanospheres Using the Hydrodynamic Model
https://jap.alzahra.ac.ir/article_7402.html
In this study, The surface plasmon excitations in a dimer structure of closely spaced metallic nanospheres with different radii are investigated using the hydrodynamic model. Initially, an expression was derived to calculate this structure's multipolar surface plasmon excitations. Subsequently, the surface plasmon excitations in the dipole approximation were examined.The surface plasmon excitations in a dimer structure of closely spaced metallic nanospheres with different radii are examined using the hydrodynamic model in this study. It has been observed that the energy of in-phase modes is lower than that of out-of-phase modes in longitudinal or transverse excitations. Furthermore, at each separation distance between the nanospheres, the energy difference between in-phase and out-of-phase longitudinal modes is greater than that of transverse modes. The results show that with an increase in the separation distance between the nanospheres, the energies of in-phase modes increase, and the energies of out-of-phase modes decrease. At large separation distances, two plasmon modes are obtained, with the higher energy mode corresponding to the smaller nanosphere and the lower energy mode corresponding to the larger nanosphere. Finally, the local limit results are presented for comparison.Research Paper: Calculation of the Electronic and Optical Properties of ZnX (X=Se, S) Nano-layer Using Density Functional Theory
https://jap.alzahra.ac.ir/article_7371.html
In this study, the optical and electronic properties of bulk and nano-layer of zinc selenide (ZnSe) and zinc sulfide (ZnS) are investigated. The calculations for solving the many-body Schrodinger equations are performed in the framework of density functional theory using the WIEN2K computational package. The Engel-Vosko and gradient generalized approximation (GGA) treat the exchange-correlation potential. To investigate the electronic and optical properties of zinc selenide and zinc sulfide nano layers, the electronic band structure and the real and imaginary parts of complex dielectric function for the bulk and nano-layer with different thicknesses are calculated and compared. The results of electronic band structures show that the energy band gap of zinc selenide and zinc sulfide nano-layers with various thicknesses decreases to zero and are metal. In contrast, the bulk of zinc selenide and zinc sulfide compounds are semiconductors. The results also show that for each compounds the static dielectric function for the perpendicular and parallel direction to the nano-layer surface is different from the bulk static dielectric function. Comparison between the real parts of complex dielectric function for the bulk and nano-layer shows that absorption of electromagnetic radiation for the ZnSe and ZnS nano-layer in comparison to corresponding bulk results occur in lower energies.&nbsp;&nbsp;Research Paper: Design and Fabrication of V-Shaped Resonator for Using in Laser Spectroscopy Based on Optical Feedback Cavity Enhanced Absorption Spectroscopy
https://jap.alzahra.ac.ir/article_7443.html
In this study, we present the design and fabrication of a V-shaped resonator that served as an absorption chamber in a laser spectroscopy system for water stable isotope measurement (2H, 17O, 18O) based on optical feedback cavity-enhanced absorption spectroscopy. In the design of a resonator, its length and the radius of curvature of the mirrors guarantee the optical stability of the system. The resonator mirrors are designed considering the condition of stability and based on the desired mode structure of the resonator output. The V-shaped resonator is designed with two arms of 40 cm and inner diameters of 5 mm making an angle of 1.7&deg;. This resonator has an internal volume of 20 cm3 which provides fast response of laser spectrometer. The high reflectivity of mirrors leads to an effective absorption optical path length of 13 km and a high finesse optical resonator of&nbsp;&nbsp; Ƒ~52،000. These values allow low concentration water vapor isotope analyses and resolution of the absorption spectrum of isotopes for accurate isotope measurements, respectively. Resonator mirrors are designed using Mcleod software to have maximum reflectance at a wavelength of 1.4 micrometers. By making a V-shaped optical resonator for measuring stable isotopes of water and subsequent development for measuring stable isotopes of other elements, the possibility of developing the application of stable isotopes in different areas of research will be provided.Research Paper: Producing and Characterizing Silver Nanoparticles Stabilized on GO and Investigating the Effect of Ultraviolet Radiation on their Nonlinear Behavior
https://jap.alzahra.ac.ir/article_7564.html
In this research, graphene oxide was prepared by Hamers' improved method, then, with the electric arc method, silver nanoparticles enter the graphene oxide environment diluted with deionized water, and a colloid of core-shell,silver-silver oxide is prepared. After the samples were prepared, graphene oxide plates containing silver nanoparticles were fixed on them, and samples with the same concentration and volume were placed under ultraviolet radiation for 0, 30, 60, 120, and 240 minutes, respectively. Then, various spectra are prepared from the samples and their linear and non-linear behavior is studied in two experiments, Z-scan and phase spatial modulation. The results of ultraviolet-visible spectroscopy, infrared Fourier transform, and X-ray diffraction show that the resulting solution contains graphene oxide nanoplates and silver oxide nanoparticles. Investigating the nonlinear optical properties of the samples also shows that the nonlinear refractive index of the samples is of the order of , which by ultraviolet radiation to the samples, their nonlinear refractive index changes slightly, and on the other hand, the diffraction pattern with two peaks is observed in the formed structure.Research Paper: Effect of Femtosecond Laser Polarization on The High- Harmonic Generation from Formaldehyde Molecule
https://jap.alzahra.ac.ir/article_7565.html
In this work, we study the interaction of femtosecond laser with formaldehyde molecule and investigate the effect of intensity and angle of laser polarization on the high harmonic generation. The calculation is done with time-dependent density functional theory in three-dimensional real space. The effect of the ellipticity parameter and the role of different orbitals of this molecule on the high harmonic spectrum is investigated, so that the contribution of different orbitals of the formaldehyde molecule in this process can be controlled. The maximum intensity and the maximum width of the high harmonic spectrum are obtained for the ellipticity parameter of 0.15. Also, if the large diameter of the ellipse of laser polarization is along the y-axis, the intensity of the harmonic spectrum is increased, and the reason for this process is discussed by analyzing the time evolution of the population of ionized electrons. In the following, the effect of incident laser polarization on the output attosecond pulse polarization and its width is investigated, which is resulted in the generation of an elliptically polarized attosecond pulse.Research Paper: Shocks and Energy Transfer in Solar Atmospheric Jets
https://jap.alzahra.ac.ir/article_7567.html
The aim is to study nonlinear wave dynamics in solar spicules and jets. The life of jets in the context of Alfven wave dynamics is focused. Here, further insight into the solar atmospheric effects together with initial conditions on the dynamics of Alfven waves along with the characteristic parameters of the spicule or jet itself are provided. Results are based on the theory of magnetohydrodynamics. the location of shock formation by the interplay of the internal and external plasma-beta conditions together with the initial steady flow speeds which are rooted in the initiation location of the solar jet are illustrated. It was known that the plasma-beta of a solar jet affects the shock formation time of torsional Alfven waves. However, its efficiency is shown to be dependent on the external plasma beta conditions. The shock formation time for plasma-beta conditions over unity is directly proportional to the plasma-beta, similar to plasma-beta conditions equal to or below unity. In the case where the plasma-beta inside the magnetic structure is small, the shock formation time is accelerated by increasing the external plasma-beta. In photospheric conditions, as for coronal conditions, the time of shock formation is inversely proportional to the external plasma-beta. When the internal plasma-beta is fixed, for various steady flow speeds, the external plasma-beta accelerates the formation of shocks. These results help us to better understand the role of Alfven waves in solar jets in the transfer of energy to the solar system.Research Paper: Investigating the Electric Power Performance of the Shock Wave Device and Explosion of Aluminum Wire in a Water Environment
https://jap.alzahra.ac.ir/article_7570.html
The shock wave or plasma pulse method was presented for the first time in oil wells to solve the problem of worldwide pressure drop and well production. In this study, the technology of underwater electric wire explosion (UWEWE) has been investigated to generate shock waves by using a sudden discharge of very hot plasma energy at a point and then creating a shock wave. The constructed plasma emitting device consists of two electrodes, a set of high voltage capacitors with a voltage of 5 kV and a capacity of 80 microfarads, an electronic block, a Rogovsky coil installed in the electric discharge circuit, and a relay block. For aluminum wire with a diameter of 400 and 500 mm and a length of 30 mm, with a pulsed current at a discharged voltage of 3.8 kV, the total energy deposition is 400 and 500 J, with the energy conversion efficiency of 68 and 66.3%, respectively, and a maximum power of 168 MW.Atomic Gradiometer for Recording the Simulated Human Brain Signal in Unshielded Environment
https://jap.alzahra.ac.ir/article_7572.html
The fields resulting from the brain's neural activities provide essential information in diagnosing and treating brain diseases such as epilepsy, convulsions, and brain tumors. Recording brain magnetic field signals is one of the non-invasive brain functional imaging methods, which usually requires magnetic shielding besides expensive and bulky instruments. Although atomic magnetometers are inherently less sensitive than superconducting quantum interference devices, they are considered the best candidate for measuring bio-magnetic fields due to their low manufacturing cost, small size, and no need for cryogenic equipment. Atomic magnetometers measure the low-strength brain magnetic fields based on detecting Zeeman energy splitting and recording changes in the laser light intensity passing through an alkali vapor cell. To improve the sensitivity of these magnetometers, it is common to remove homogeneous noises in two magnetometer channels. For this purpose, we have presented a gradiometer to suppress unwanted magnetic noises. This gradiometer consists of two atomic magnetometers capable of detecting the field produced by the human brain in an unshielded environment in the presence of the Earth's magnetic field. The gradiometer has a sensitivity of 900 fT&frasl;&radic;Hz. The designed and built gradiometer is suitable for detecting brain magnetic fields, which can be expanded as a multichannel to record the map of the brain's magnetic field.Research Paper: High Fidelity Noiseless Linear Amplifier Based on Three-Photon Quantum Scissor
https://jap.alzahra.ac.ir/article_7579.html
&nbsp;In this article, we suggested a three-photon quantum scissor that truncates all multiphoton number states with four or more photons and amplifies the remaining photon number states in a probabilistic way. To this end, by assuming the ideality of all beam splitters and detectors of the proposed scheme, the output state of this quantum scissor and its success probability have been derived analytically. In contrast to the one-photon or two-photon quantum scissor, this setup works perfectly for superpositions of up to three photons. For the input coherent state, our results show that the fidelity between ideal amplification and the amplification obtained by this suggested three-photon quantum scissor is as good as that obtained with a network of six one-photon or two two-photon amplifiers. Moreover, the success probability of this generalized quantum scissor is larger than the success probability of six one-photon amplifiers and is comparable to the success probability of two two-photon amplifiers. Therefore, based on the fact that the resources required by the three-photon amplifier are smaller than those required for a network of one-photon or two-photon amplifiers, this proposed device is much more efficient than several one-photon or two two-photon amplifiers.Research Paper: Design and Construction of a Plasma Generation Device Using the Surface Dielectric Barrier Discharge (SDBD) Method in a Laboratory Scale
https://jap.alzahra.ac.ir/article_7594.html
This article aims to design and construct a plasma generation device using the surface dielectric barrier discharge method (SDBD) on a laboratory scale to produce a stable and uniform atmospheric pressure plasma layer. For this purpose, a copper electrode with a thickness of 100 microns with a comb- like structure was designed and constructed for this system, and a mica sheet with a thickness of 0.5 mm and dimensions of 10 &times; 10 cm was built to make the dielectric. According to the experimental data and analytical calculations of the constructed SDBD system in working conditions of 3 kV voltage and 12.5 kHz frequency, the consumption power of this system is calculated at 50 watts. Due to the production of stable and uniform plasma created on the dielectric surface and the measured power consumption, this system will be able to be used in various sciences and industries, including surface processing industries.Influence of Thermal Fluctuation on Attractive and Repulsive Casimir Forces in Microsystem with Topological Insulator Material
https://jap.alzahra.ac.ir/article_7610.html
Here,&nbsp;we explore the sensitivity of the Casimir force between two topological insulator plates on&nbsp;thermal fluctuation using weak and strong magnetizations on the surface of plates via Lifshitz theory.&nbsp;Thermal fluctuations between two plates made of topological insulators in vacuum lead to attractive interactions. By considering a weak magnetization, the influence of thermal fluctuations becomes stronger compared to the magnetoelectric effect in the regime of large separations which leads to generating the strong attractive Casimir force. Moreover, by considering strong magnetizations it is observed that thermal effects cannot make a change in the attractive and repulsive Casimir forces, and magnetoelectric effect determines both the magnitude and direction of Casimir forces. In the range of small magnetization, thermal effects have a significant effect on the repulsive Casimir force. It has been shown that at high temperatures, repulsive interaction due to antiparallel magnetization becomes weak, so that they disappear by increasing the separation.