Indian Journal of Physics最新文献

{"title":"Self-consistent Maxwell-Dirac theory","authors":"Sergey A. Rashkovskiy","doi":"10.1007/s12648-024-03125-3","DOIUrl":"10.1007/s12648-024-03125-3","url":null,"abstract":"<div><p>We show that quantum mechanics can be constructed as a classical field theory that correctly describes all basic quantum effects, by combining the Maxwell and Dirac equations. It is shown that for a self-consistent union of the Maxwell and Dirac equations into a unified classical field theory, it is necessary to introduce an additional short-range tensor field, which compensates the intrinsic electrostatic field of the electron wave inside the atom. For the combined Maxwell-Dirac field, the stress-energy tensor is constructed. We show that in the nonrelativistic limit this theory naturally transforms into the self-consistent Maxwell-Pauli theory and allows describing all basic quantum effects in the framework of classical field theory without any quantization.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"98 10","pages":"3431 - 3438"},"PeriodicalIF":1.6,"publicationDate":"2024-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141575642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Three propagation regimes of Laguerre–Gaussian laser beams in collisionless plasma","authors":"Sanyogita S. Patil, Kalyani Y. Khandale, Prasad T. Takale, Prajakta P. Patil, Mansing V. Takale, Sandip D. Patil","doi":"10.1007/s12648-024-03326-w","DOIUrl":"https://doi.org/10.1007/s12648-024-03326-w","url":null,"abstract":"<p>Nonlinear optical effects in plasmas associated with light beams carrying orbital angular momentum are realizable in the form of Laguerre–Gaussian beams (LGBs) popularly known as twisted light. In this paper, the effect of angular mode index of light on propagation of LGBs in plasma is investigated by considering ponderomotive nonlinearity. A paraxial-like approach is adopted to establish nonlinear differential equation for beam-width parameter. Three distinct regimes characterizing nature of propagation are obtained for different modes of LGBs. The essential critical as well as divider curves and corresponding changes in beam width parameter with propagation distance of LGBs are assessed. It is found that orbital angular momentum of a light beam significantly affects the self focusing characteristics of LGBs in plasma.</p>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"18 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141575641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of noise-anharmonicity interplay on Shannon entropy and heat capacity of GaAs quantum dot","authors":"B. Bhakti, S. Datta, M. Ghosh","doi":"10.1007/s12648-024-03320-2","DOIUrl":"https://doi.org/10.1007/s12648-024-03320-2","url":null,"abstract":"<p>Current investigation explores the <i>Shannon entropy</i> and the corresponding <i>heat capacity</i> of <i>GaAs</i> <i>quantum dot (QD)</i> under the simultaneous impact of <i>anharmonic potential</i> and <i>Gaussian white noise</i>. The <i>parity</i> of anharmonicity (odd/even), the type of Gaussian white noise (additive/multiplicative) and the confinement potential of the QD undergo highly subtle interaction to modulate the entropy and the heat capacity. Presence of odd (even) anharmonic potential diminishes (enhances) the energy of QD in comparison with the condition without anharmonic potential. In general, multiplicative (additive) noise brings about larger (smaller) departure of the thermodynamic properties from the situation devoid of noise. Moreover, additive (multiplicative) noise enhances (depletes) the strengths of the thermodynamic properties in comparison with the state without noise. The enquiry further manifests the competitive behaviour between thermal and spatial disorder (multiplicative noise) that noticeably influences the said thermal properties.</p>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"43 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141551335","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Studying the effects of ambient temperature, chemical potential and external magnetic field on the enhanced Faraday rotation in multilayered structures containing a hybridized topological insulator thin film","authors":"Abbas Ghasempour Ardakani, Hadi Asgari Sarcheshmeh","doi":"10.1007/s12648-024-03325-x","DOIUrl":"https://doi.org/10.1007/s12648-024-03325-x","url":null,"abstract":"<p>In this paper, we insert a hybridized topological insulator thin film in a dielectric multilayered structure with a defect layer to enhance the Faraday rotation at the terahertz region as well as transmittance. By employing the transfer matrix method for anisotropic interfaces, it is demonstrated that Faraday rotation in this structure at defect modes is significantly stronger compared to the case at which the hybridized topological insulator layer used as a defect in the multilayered structure or a suspended topological insulator layer in air. The absolute value of positive Faraday rotation angle at defect modes for the transverse magnetic polarized incidence is so larger than one of negative Faraday rotation angle for the transverse electric polarized incidence. Furthermore, the dependence of Faraday rotation angle on the ambient temperature, external magnetic field and chemical potential is studied for both TE and TM polarizations. Faraday rotation at defect modes is diminished with increase of temperature and chemical potential. In some defect modes, Faraday rotation enhances with the increase of external magnetic field, while in others it first increases and then decreases.</p>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"16 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141551336","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of lockdown due to COVID-19 on environmental pollutant: a comparative study between top three countries of the world","authors":"Sanjay Kumar","doi":"10.1007/s12648-024-03323-z","DOIUrl":"https://doi.org/10.1007/s12648-024-03323-z","url":null,"abstract":"<p>Pandemic from Corona Virus Diseases 2019 (SARS-COVID-19) is a serious hazard to human health and life which is responsible for the significant economic losses across the world. Sometime it resulted into death of human being. Since environmental factors have significant effects on COVID-19 transmission, and vice-versa, therefore lockdown condition which is expected to reduce environmental pollution is an important step to affect COVID transmission through the environment. The associated ambient air pollutant: (O₃), nitrogen dioxide (NO₂), sulphur dioxide (SO₂), and Carbon mono oxide (CO) are directly linked to enhance risk of stroke, heart disease, asthma, and lung cancer and are also affected by the number of cases of COVID-19. In order to have quantitative estimate and comparative study of these pollutants, aerosol optical depth (AOD), surface temperature, ozone, carbon mono oxide (CO) and nitrogen dioxide (NO₂), aerosol size distribution over India, have been analysed during lock down period 01 March–30 June, 2020. The analysis of pollutants during lockdown period has been compared to 05 year mean value (2015–2019) estimated during the same period. The satellite based measurement of AOD from MODIS show a decrease in AOD during the lockdown period by 40% in Indian region as compared to 5-year mean level (2015–2019) whereas ground based AOD from AERONET reduced to 75% at Kanpur and 74% at Gandhi College in India. The drop in AOD observed during lockdown is a clear cut indication of reduced level of air pollution. Peak of aerosol size distribution over Kanpur and Gandhi College has also been analysed which show a reduction by 33–50% from the 05-year average level. Enhancement in total ozone column ~ 8% from average level is noticed during the lockdown period which is attributed to suppression in NO₂ and CO concentration which is supposed to destroy the formation of ozone through chemical reactions. Influence of lockdown on concentration of environmental pollutants in Indian region has also been compared to top other two countries of the world: USA and Brazil. The pattern of day-to-day variation of COVID cases at India and Brazil is same whereas for USA patterns are significantly different. The comparative analysis of other pollutants between all the three countries has also been discussed and fall in temperature due to lockdown condition over USA is found larger than that over India and Brazil.</p>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"167 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141519174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of constant and spatially varying higher-order dispersions on spatial solitons in $$mathcal{P}mathcal{T}$$ -symmetric optical media under the alternative complex potentials","authors":"Boubakary Abdou, Fabien II Ndzana, Camus Gaston Latchio Tiofack, Alidou Mohamadou","doi":"10.1007/s12648-024-03317-x","DOIUrl":"https://doi.org/10.1007/s12648-024-03317-x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>We investigated analytically and numerically the nonlinear Schrödinger (NLS) equation with constant and spatially varying third-order dispersion (TOD) in the alternative type of complex parity-time <span>((mathcal{P}mathcal{T}))</span>-symmetric potentials. This equation describes the propagation of ultra-short pulses through the optical media, where the real part of the potential models the index guiding and the imaginary part the loss/gain distribution of light within optical material. For the constant TOD, the regions of stability/instability linear <span>(mathcal{P}mathcal{T})</span>-symmetric phases are numerically carried out. By means of the linear stability analysis and direct numerical simulation, the effects of interplay between constant TOD and <span>(mathcal{P}mathcal{T})</span>-symmetric potential on the stability of these solutions are also tested. It is found that the constant TOD can be used to control the stability of these solutions. For the spatially varying TOD, the additive terms of the <span>(mathcal{P}mathcal{T})</span>-symmetric potential are considered for the nonlinear model and the robustness of these solutions against noise is tested by means of the split-step Fourier beam technic. Moreover, the elastic interactions of the two spatial solitons are generated under the <span>(mathcal{P}mathcal{T})</span>-symmetric potential for the spatially varying TOD. The power and the transverse power-flow density are further examined. Results indicate that the spatially varying TOD does not yield any instability in the self-focusing nonlinear medium with the chosen parameters values.</p><h3 data-test=\"abstract-sub-heading\">Graphical Abstract</h3>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"22 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141519177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An investigation of the structural and optical properties of modified barium magnesium fluoroborate glasses with hafnium oxide (HfO2)","authors":"A. M. Abdelghany, M. S. Abdel Aal, R. Seoudi","doi":"10.1007/s12648-024-03302-4","DOIUrl":"https://doi.org/10.1007/s12648-024-03302-4","url":null,"abstract":"<p>Glasses of nominal composition <i>x</i>HfO₂–(35-<i>x</i>)B₂O₃–15MgF₂–35BaO, where <i>x</i> ranged from 0 to 0.2 mol% were fabricated using a melt-quenching technique. Structural characterization techniques, including X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and Raman spectroscopy, were employed to elucidate the glass network structure. The XRD patterns confirmed the amorphous nature of the studied glasses, while the FTIR and Raman spectra revealed that the incorporation of HfO₂ may led to a transformation of trigonal BO₃ units to tetrahedral BO₄ units in the borate glass network. Deconvolution analysis of the FTIR and Raman bands provided quantitative insights into the extent of this structural rearrangement as a function of HfO₂ content. UV–Vis absorption studies demonstrated that the optical bandgap of the glasses was widened with increasing HfO₂ additions. This blue shift in the absorption edge was attributed to the increased formation of bridging oxygen bonds and reduced non-bridging oxygen content in the glass network. The results indicate that the studied glasses exhibit excellent compositional tunability through the incorporation of HfO₂. The structural modifications and concomitant optical property enhancements suggest the potential of this glass system for various integrated photonic applications where low phonon energy and tailored transparency are highly desirable. The present work introduces a comprehensive investigation of the structural and optical property modifications in barium magnesium fluoroborate glasses induced by the addition of hafnium oxide (HfO₂).</p>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"13 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141519179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of thermo-optic and thermo-polarizability coefficients of ions in congruent LiNbO3 open-type optical waveguide using point dipole approximation","authors":"Velagapudi Suhasini,&nbsp;I. V. Subbareddy,&nbsp;Pasunooti Manoher","doi":"10.1007/s12648-024-03072-z","DOIUrl":"10.1007/s12648-024-03072-z","url":null,"abstract":"<div><p>The thermo-optic coefficients (TOCs), thermo-polarization coefficients (TPCs) and dn/dT, d<i>α</i>/d<i>T</i> of congruent lithium niobate LiNbO₃ / LN (mole ratio Li/Nb = 0.946) are tested within the temperature range of 293–773 K at <i>λ</i> = 0.4358 µm, <i>λ</i> = 0.6328 µm and <i>λ</i> = 1.15232 µm employing the point dipole approximation. The refractive indices, <i>n</i>_<i>o</i> and <i>n</i>_<i>e</i>, were first determined at these temperatures and wavelength ranges, by iterating the electronic polarizabilities of Nb⁵⁺ and O²⁺ ions. It has been found that the polarizability of Nb⁵⁺ ions drops and that of O²⁻ ions increases when temperature rises for a particular wavelength. Both Nb⁵⁺ and O²⁻ lose polarizability with increasing wavelength for a given temperature. TOCs for n_o and n_e rise as the temperature rises. The TOC rises as wavelength for <i>n</i>_<i>o</i> and <i>n</i>_<i>e</i> decreases. TPCs of O²⁻ rise in ions and temperature causes Nb⁵⁺ ions to decrease. At a particular temperature, TPCs of O²⁻ions become less while Nb⁵⁺ ions grow as wavelengths rise. Generally, it is used in potential electronic polarizabilities and thermal refraction applications.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"98 10","pages":"3681 - 3688"},"PeriodicalIF":1.6,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141519173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Condensation of ideal Dunkl–Bose gas in power-law traps","authors":"A. Hocine, F. Merabtine, B. Hamil, B. C. Lütfüoğlu, M. Benarous","doi":"10.1007/s12648-024-03311-3","DOIUrl":"https://doi.org/10.1007/s12648-024-03311-3","url":null,"abstract":"<p>We study the phenomenon of Bose–Einstein condensation in two- and one-dimensional Dunkl–Boson gases confined within a power-law potential, employing the framework of Dunkl-deformed boson theory. Our investigation involves the calculation of particle numbers and phase transition temperatures using the Dunkl formalism. To assess the validity of our findings, we compare them with the corresponding results obtained from the standard approach. We find that the impact of the Dunkl formalism on the condensate fractions is similar in one- and two-dimensional cases. However, we see that this conclusion is not fully valid for the phase transition temperature.</p>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"37 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141531326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design prospect of CdTe solar cell using NW-CdS window layer and 3D graphene as back electrode from numerical approach","authors":"Laxmi Vandana, Shrabani Guhathakurata, Gufran Ahmad, Sandipan Mallik","doi":"10.1007/s12648-024-03293-2","DOIUrl":"https://doi.org/10.1007/s12648-024-03293-2","url":null,"abstract":"<p>In this work, a new cadmium telluride (CdTe) photovoltaic structure has been developed to achieve a high-power conversion efficiency (η) at low cost for thin film photovoltaic. The blue spectrum is surprisingly restricted by the cadmium sulfide (CdS) window layer in the CdTe solar cell. Thus, to improve the shorter wavelength collections, we have replaced the planar CdS layer with nanowire CdS (NW-CdS) window layer. With this change, the quantum efficiency has significantly improved in a shorter wavelength range and the photocurrent has increased by more than 27% compared to the planar CdS device structure. Furthermore, a good back contact material with lower contact resistivity is also important to achieve maximum power conversion efficiency. To obtain an Ohmic, low-resistance contact, a 3D graphene layer has been used as a back contact. Using the SCAPS-1D simulation software, the newly proposed CdTe solar cell’s photovoltaic characteristics were thoroughly investigated. Our calibrated simulation results show that the suggested NW-CdS with graphene solar cell structure produce higher photocurrent density (J_SC) and fill factor (FF). The power conversion efficiency (η) was found to be 14.58%, comparatively higher than the baseline CdTe solar cell efficiency (η = 9.04%).</p>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"20 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141532644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}