نشریه پژوهش سیستم های بس ذره ای
سال دهم شماره 1 (پیاپی 24، بهار 1399)

In this paper, we designed and simulated the circular photonic crystal fibers (C-PCFs) for guiding and controlling the orbital angular momentum (OAM) of light. The optimum parameters in C-PCFs were archived by considering the conditions that eliminate the spin-orbit coupling for each guided mode. Moreover, for optical communication applications, a flat modal dispersion is required for a wide wavelength range from 1.25 to 2 µm and the OAM modes must have a low confinement loss. For different fractions of air filling (f), the results were simulated and compared to achieve the best values of f. According the simulated results, the proposed design of C-PCF can support a group of OAM modes up to HE51 and EH31 with topological charge of l=4. Furthermore, our C-PCF shows high quality in terms of dispersion and OAM mode losses, which can additionally be used in space-division multiplexing rather than the conventional wavelength-division multiplexing for optical communication systems.

Assuming, a symmetric system with N qubits under Hamiltonian one-axis twisting and different kinds of noisy channels, such as amplitude damping, phase-flip and phase-damping channel, it is studied the time evolution of quantum correlation and entropic uncertainty relation in the presence of quantum memory. By comparing the behaviors of the dynamics of entropic uncertainty and quantum correlation, it is shown that they increase with increasing of the number of qubits in the beginning of the time. But, they behave in contrary to each other, during the time. As a result, the uncertainty of incompatible observables increases, when quantum correlation decreases.

We consider the sign of holographic n-partite information in holographic model with momentum relaxation. The system consists n disjoint strips with the same separation and width. The momentum dissipation is achieved by the spatially-dependent scalar fields. We particularly show that triprtite information is always negative, which implies that the holographic mutual information is monogamous. We also study the monogamy property of 4-partite information by considering the sign of holographic 5-partite information. It is shown that in 2-dimensional dual field theory, the 4-partite information holds the monogamy relation. Finally we examine the holographic quantum phase transition of these quantities. Our results indicates that in the presence of momentum relaxation parameter, the transition takes place in smaller separation of subsystems.

In this paper, the design and simulation of a functional nano-particles nano-sensor is presented by combining the structure of an optical microdisk resonator and photonic crystal in the form of an array of cubic air-holes along the circular path near microdisk’s periphery. Finally, the design of slots with a depth of about a fraction of the thickness of the disk, which links the neighboring air-holes in the same circular path, helps to create special conditions for making the nano-particles sensor device. In this combined structure, small modal volume with very high quality factor modes is provided to confine optical modes for sensing. We report values as 0.075(λ/n)3 for the modal volume in the centralized slot area for modes with a quality factor larger than 10 million, using finite element method simulation. Sensing properties of the structure are analyzed using variation of wavelength of the modes for different disk geometries, photonic crystal array, and the dimensions of the linked slots, and access to an acceptable sensitivity 109 nm/RIU (nm/refractive index unit) is possible.

In this paper, we try to estimate the non-universal parameters of some discrete growth models belonging to the Kardar-Parisi-Zhang (KPZ) universality class in both one and two dimensions. Based on a comprehensive numerical investigation, we obtain these parameters with good accuracy compared to other reports. The most important result of the present paper is the estimation of the nonlinear parameter of the KPZ equation with excellent accuracy. For this purpose, we apply the tilt method as a useful tool to characterize the nonlinearities of their associated equation. We believe this method can be used to ensure that there is a nonlinearity type square height-gradient for others discrete growth models.

Increasing demand for highly sensitive, selective, affordable, low-consumption, durable and portable sensors has led to extensive research into the use of two-dimensional materials. Two-dimensional materials are very suitable for making gaseous sensors due to good optical clarity, high flexibility, high mechanical strength, and special electronic and optoelectronic properties. In this paper, the electronic, optical and magnetic properties of pure and defected silicene monolayer in the presence of carbon monoxide gas has been studied using first principles calculations based on density functional theory and time-dependent density functional theory. According to the investigations, we find that the optical and electronic properties of the system are altered by the absorption of the gas molecule and the vacancy defect. Here, the electron energy loss spectroscopy for pure silicene monolayer in the presence of gaseous molecule and vacancies defect have been investigated. The spectrum associated with them indicates that the plasma peak changes (Collective modes).

In this paper we investigated longitudinal acceleration of a test electron using a Gaussian laser pulse through an underdense magnetized plasma channel. We have shown that parameters like amplitude and polarization angle of the laser pulse, density of plasma and the strength of magnetic field significantly influence the dynamics of electrons. We find that presence of magnetic field in the plasma channel increases the required density threshold for electron acceleration. Here, we examine the dependence of electron acceleration on various parameters in the magnetized plasma channel and compare it with non-magnetized case. According to numerical results for polarization angle the presence of magnetic field intensifies electron acceleration in the plasma channel.

For investigation of the processes occurred in solar cells, lots of optical and electrical modes are used. In this study, optical simulation of perovskite solar cell based on transfer matrix formalism using complex refractive index (as a function of wavelength) of multilayer structure is presented. In other words, optical properties such as, optical absorption, energy dissipation and incident electrical field distribution of the perovskite solar cells with different electron transporting materials by matrix method are studied. Then, in order to obtain the optimum thickness of the active layer, the effect of it’s thickness on the short-circuit current density are investigated and the optimum structure is selected

In this work, we consider the Jaynes-Cumming (J-C) interaction in which the particles of the system exposed to the bosonic bath. It is supposed that the system includes two spins 1/2 particles with the spin-exchange interaction. It assumes that each of the particles is in a separate bosonic bath with the Cauchy-Lorentz distribution. using the Liouville-von Neumann equation and applying the Born approximation, we obtain the density matrix of the system as a function of both time and temperature during the Non-Markovian processes. Moreover, in order to calculate the specific heat, a new formula is presented by using the eigenvalues of the density matrix. we consider the quantum entanglement (EN) as a function of time, temperature and the other parameters in Hamiltonian. The results obtained from these investigations show that, when the temperature of the system tends to zero, the state of system takes the maximum value of Entanglement (EN) and the specific heat diverges. The other result is the negative amount in specific heat at the moment of the system attached to the environment. These results play an important role in designing the solid quantum gates whose operations are based on the EN and thermal properties of the environment.

In this paper, by using first principle method we address the variation of bulk plasmon frequencies of diamond crystal underlying hydrostatic pressure in the rang 0-100 GPa. Further, optical properties such as reflectivity coefficient is also calculated. Based on electronic structure, density of transition probability and electron energy loss function, results show that by increasing the pressure to 100 GPa, plasmon excitation shifts to higher energies about 4 eV in the near ultra-violet regime along with increasing the electronic band gap. That is while enhancing the pressure would reduce the plasmon lifetimes via the formation of electron-hole pair. Our finding shows that the modulation of all optical features such as collective plasmonic excitations are possible by manipulation and control of dielectric function by external probes such as pressure.

The fabrication tolerances for a coaxial to WG1800 waveguide coupler cause the variations of its electromagnetic parameter such as the working frequency. In order to investigate the effect of these uncertainty on the electromagnetic parameters, Monte Carlo method is usually used, which is very time consuming. In this paper, the generalized Polynomial Chaos (gPC) method is first used for study the effect of variations of dimensions of a WR187 rectangular cavity on the resonant frequency. To assessment the accuracy of this method, these results are compared with the Monte Carlo and the theory methods. In the second step, the effect of variations of dimensions of a coaxial to WG1800 waveguide coupler on its frequency is investigated using the gPC Method. Key Words: Fabrication tolerances, Variations, Monte Carlo, generalized Polynomial Chaos, frequency.

In this paper, we consider the anisotropic super Yang-Mils plasma at finite temperature and and calculate its conductivity in the presence of a constant electric field. By applying the electric field in two different directions, we study the effect of the electric field, charge density and anisotropy parameter on the electrical conductivity of the plasma. We first consider the constant external electric field in the longitudinal x-direction, and then the external electric field is applied to the system in the longitudinal z- direction. At the end, we compare the results of two different directions with each other. Also, we compare the results with those from isotropic Ads-Schwarzschild black hole and non-critical Ads6 model.