Volume 65, Number 78, 2020
Theoretical, Mathematical, and Computational Physics
Remarks on the Geometry of the Extended SiegelJacobi Upper HalfPlane Elena Mirela Babalic, Stefan Berceanu Romanian Journal of Physics 65,
113 (2020)
The real Jacobi group $G^J_1(\mathbb {R})={\rm SL}(2,\mathbb {R})\ltimes {\rm H}_1$, where ${\rm H}_1$ denotes the 3dimensional Heisenberg group, is parametrized by the $S$coordinates $(x,y,\theta ,p,q,\kappa )$. We show that the parameter $\eta $ that appears passing from Perelomov's unnormalized coherent state vector based on the SiegelJacobi disk $\mathcal {D}^J_1$ to the normalized one is $\eta =q+\rm {i} p$. The twoparameter invariant metric on the SiegelJacobi upper halfplane $\mathcal {X}^J_1=\frac {G^J_1(\mathbb{R})}{\rm {SO}(2)\times \mathbb {R}}$ is expressed in the variables $(x,y,\rm {Re}~\eta ,\rm {Im}~\eta )$. It is proved that the five dimensional manifold $\tilde {\mathcal {X}}^J_1=\frac {G^J_1(\mathbb{R})}{\rm {SO}(2)}\approx \mathcal {X}^J_1\times \mathbb {R}$, called extended SiegelJacobi upper halfplane, is a reductive, nonsymmetric, nonnaturally reductive manifold with respect to the threeparameter metric invariant to the action of $G^J_1(\mathbb {R})$, and its geodesic vectors are determined.
Third Order Anomalies in the Causal Approach D. R. Grigore Romanian Journal of Physics 65,
114 (2020)
We consider gauge models in the causal approach and study the third order of the perturbation theory. We are interested in the computation of the anomalies in this order of the perturbation theory and for this purpose we analyse in detail the causal splitting of the distributions with causal support relevant to tree and loop anomalies.
Quintom Cosmology with Generalized Galileon Corrections M. Marciu, F.V. Iancu, D.M. Ioan, V. Baran Romanian Journal of Physics 65,
115 (2020)
In this work we have considered a quintom cosmological model with generalised Galileon corrections in the scalar tensor theories of gravitation. After proposing the corresponding action of the cosmological model we have deduced the KleinGordon equations and the modified Friedmann relations. By introducing the auxiliary variables we have described the evolution of the model as an autonomous dynamical system of differential equations for generalised powerlaw coupling functions. Assuming various initial conditions we have analyzed the dynamical features of the phase space, obtaining the numerical evolution of the effective equation of state and the density parameters, respectively. It is observed that for different initial conditions the system evolves from an initial phantom epoch towards a deSitter stage in which the model behaves closely to a cosmological constant, approaching the phantom divide line boundary from bellow asymptotically.
A Note on Proper Conformal Vector Fields of Static Spherically Symmetric SpaceTimes in f(G) Theory with Perfect Fluid Source Fiaz Hussain, Ghulam Shabbir, F. M. Mahomed, Muhammad Ramzan Romanian Journal of Physics 65,
116 (2020)
The aim of this paper is to investigate proper conformal vector fields of static spherically symmetric spacetimes in the f(G) theory. Firstly, we explore some perfect fluid solutions of the Einstein field equations in the f(G) theory of gravity using algebraic technique. Secondly, we investigate proper conformal vector fields of the solutions obtained via the direct integration approach. Studying each case in detail we show that a very special class of static spherically symmetric spacetimes admit proper conformal vector fields.
On General HighOrder Solitons and Breathers to a Nonlocal SchrödingerBoussinesq Equation with a Periodic Line Waves Background Wei Liu, Jiguang Rao, Xiaoyan Qiao Romanian Journal of Physics 65,
117 (2020)
General highorder soliton and breather solutions to a nonlocal SchrödingerBoussinesq (NSB) equation with a periodic line waves (PLWs) background are studied via the bilinear KPreduction method. We construct tau functions to the NSB equation by restricting tau functions of bilinear equations in the KP hierarchy, which generate arbitrary $2N$soliton and $N$breather solutions on a PLWs background in the NSB equation. Based on the asymptotic analysis, the twosoliton solutions are classified into nondegenerate and degenerate twosoliton solutions. The nondegenerate twosoliton has three patterns: twodarkantidark soliton, twodarkdark soliton, and twoantidarkantidark soliton. The degenerate twosoliton solution possesses two distinct patterns: the degenerateantidark soliton and the degeneratedark soliton. The foursoliton solution on the PLWs background exhibits the superpositions of two twosoliton solutions, and admits three distinct patterns: the nondegenerate foursoliton solution, the two degenerate twosoliton solutions, and the mixture of a degenerate twosoliton solution and a nondegenerate twosoliton solution. The typical dynamical scenarios of one and twobreather solutions on a PLWs background are analyzed in detail.
Dynamics of the Fidelity of Teleportation in a Gaussian Noisy Channel Marina Cuzminschi, Alexei Zubarev, Aurelian Isar Romanian Journal of Physics 65,
118 (2020)
We study the quantum teleportation of a coherent state using as a resource state an entangled twomode Gaussian state of a system of two bosonic modes interacting with a squeezed thermal environment. The evolution of the fidelity of teleportation and the logarithmic negativity of the resource state are evaluated in terms of the covariance matrix of the considered system, in the framework of the theory of open systems based on completely positive quantum dynamical semigroups. It is shown that the fidelity of teleportation and the logarithmic negativity of the resource state, which determine a successful quantum teleportation, strongly depend on the parameters characterising the initial entangled state and the squeezed thermal bath.
Time Evolution of the Gaussian Entropic Discord in a Squeezed Thermal Environment Madalin Calamanciuc, Aurelian Isar Romanian Journal of Physics 65,
119 (2020)
We describe the Markovian dynamics of the Gaussian quantum discord of a system composed of two uncoupled bosonic modes in two cases: when they are in contact with a common squeezed thermal bath, and when each of them is interacting with its own squeezed thermal bath. This study is done in the framework of the theory of open quantum systems, based on completely positive quantum dynamical semigroups. We take an initial squeezed thermal state and we show that the behaviour of the Gaussian quantum discord depends on the bath parameters (temperature, dissipation coefficient, squeezing parameter and squeezing phase), and on the initial state of the system (squeezing parameter and average photon numbers). We show that Gaussian quantum discord is decaying in time, tending asymptotically to zero, due to the effect of the environment. We also compare the Gaussian quantum discord with the Gaussian geometric discord.
Nuclear Physics
Study of LowLying States in ^{69}Ga Shashank Singh, Mumtaz Oswal, Ashok Kumar, Gulzar Singh, K.P. Singh Romanian Journal of Physics 65,
304 (2020)
Three known negative parity states of ^{69}Ga at 318.6, 574.3 and 871.9 keV were studied by Coulomb excitation technique. The safe bombarding energy for Coulomb excitation of ^{69}Ga with proton beam was obtained to be 2.5 MeV for the first time. The deexcitation gammarays were detected and identified in the singles spectra recorded with a germanium detector using 2.2–4.2 MeV proton beams. The reduced transition probabilities B(E2)↑ were determined to be 0.67 ± 0.06, 0.35 ± 0.10 and 2.09 ± 0.95 e^{2 }cm^{4 }× 10^{–50 }, respectively for these levels. Our results clearly support the Alaga model calculations produced by using three particle clustercorecoupling.
Calculation the Magnetic Dipole Moments and Quadrupole Moments for Some Exotic Chromium Isotopes Using Different Interactions A.H. Ali, B. S. Hameed Romanian Journal of Physics 65,
305 (2020)
Calculations of the magnetic dipole moments and the electric quadrupole moments in the shell model are presented for isotopes of ^{24}Cr neutronrich nuclei using fpmodel space and different interactions. These Cr isotopes are ^{49}Cr (5/2^{−}), ^{50}Cr (2^{+}), ^{51}Cr (7/2^{−}), ^{52}Cr (2^{+}), ^{53}Cr (3/2^{−}), and ^{54}Cr (2^{+}). The present calculations are made of model space (MS) and with corepolarization effects which are included through effective charge and effective g factors. The radial wave functions of the single particle matrix elements are calculated by using the harmonic oscillator (HO) potential with size parameters b which are calculated for each isotope. The onebody density matrix is calculated through the kbf, fpm, fpv interactions which in turn are carried out in the fpmodel space using the NuShellX@MSU code. Finally, these results are compared and discussed with the experimental values.
Lasers, Plasma and Beam Physics
Square Pulse Switchable Operations in Lband Fiber Ring Laser Georges Semaan, Ahmed Nady, Alioune Niang, Meriem Kemel, Mohamed Salhi, François Sanchez Romanian Journal of Physics 65,
501 (2020)
We demonstrate the generation of single, two and three square shaped pulses in a codoped Er:Yb anomalous dispersion fiber ring laser. Benefiting from increased nonlinear effects due to long cavity, various square pulse patterns are formed depending on the cavity parameters. The experimental results contribute to a better understanding of square pulse characteristics and the dynamics of multiple pulse patterns formation.
Condensed and Soft Matter Physics
Modeling Plasmonic Solar Cells with Noble Metal Nanoparticles Using the Finite Difference Time Domain Method M.M. Shabat, S.A. Nassar, H.G. Roskos Romanian Journal of Physics 65,
609 (2020)
Light trapping in solar cells can be enhanced exploiting the concept of surface plasmons innanostructures. A new type of light trapping structureutilizingnanoparticles of noble metals isinvestigated for the absorption enhancement in solar cell modules. The finitedifference timedomain (FDTD) method is used to simulate and compute the absorption spectra ofthe proposed solar cell structure.
The Influence of the Electrically Inactive Impurity on the Energy Spectrum of Electron and Hole in InAs/GaAs Heterostructure with InAs Quantum Dots R. Peleshchak, O. Kuzyk, O. Dan’Kiv Romanian Journal of Physics 65,
610 (2020)
In the framework of electrondeformation model, the influence of the electrically inactive impurity on the energy spectrum of electrons and holes in InAs/GaAs heterostructure with InAs quantum dots (QD) is investigated. Two cases are considered: the isovalent impurity of substitution and the neutral atom in the internode. It is established that the presence of the impurity in the center of spherical quantum dot leads to a decrease in energy of radiation, which corresponds to the recombination transition between the ground states of electron and hole. This effect is better manifested for small quantum dots and in the presence of interstitial impurity.
Biophysics and Medical Physics
XRD and FTIR Investigation of the Structural Changes of the Human Tooth Induced by Citric Acid M. Todica, M. MuresanPop, C. Niculaescu, M. Constantiniuc Romanian Journal of Physics 65,
706 (2020)
The structural stability of the enamel and dentine of human tooth exposed to the action of citric acid during different time intervals was analyzed by Xray diffraction (XRD) and infrared spectroscopy (FTIR) methods. Before any degradation with the acid, the XRD spectra of the enamel and the dentine show an ordered structure determined mainly by the hydroxyapatite, as well as an amorphous phase determined by other components of the enamel. This structure remains almost unaffected after 4 days of immersion in the citric acid. After a total period of 8 days of exposure to the acid, the ordered structure of the enamel and dentine is affected, but the degradation is more obvious for the dentine. This behavior is confirmed by the results obtained by FTIR investigation. It was observed that the molecular bonds of the enamel become to be affected by the acid after 4 days of immersion, a process that is amplified after 8 days. The dentine is more affected by the acid, fact confirmed by the major modification of the FTIR spectrum after 8 days of degradation. That indicates penetration of the acid into the structure of the dentine. Our study shows an acceptable protection offered by the enamel to the inner part of the tooth for short periods of time of exposure to the citric acid.
Applied and Interdisciplinary Physics
3D Digitization of Translucid Materials in Cultural Heritage Objects: a Comparative Study between Laser Scanning and Photogrammetry L.M. Angheluta, R. Radvan Romanian Journal of Physics 65,
906 (2020)
This paper presents a detailed comparative study between the two main methods of 3D digitization, photogrammetry and 3D laser scanning, regarding their performances with known difficult materials. For this study were selected two objects that were sculpted in two specific translucid materials: jade and candle wax. These types of materials are particularly hard to scan due to their special properties at the light interaction with the surface: subsurface light scattering and strong specular reflections. The paper details both data acquisition and 3D reconstruction process and discusses the results, emphasizing the advantages and disadvantages of both methods regarding the 3D digitization of this class of materials.
