Physica Scripta

Journal Information
ISSN / EISSN : 0031-8949 / 1402-4896
Published by: IOP Publishing (10.1088)
Total articles ≅ 21,199
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Latest articles in this journal

Published: 27 October 2021
Abstract:
In this paper, the performance of ridge-waveguide superluminescent light-emitting diodes (SLED) based on nitride quantum dots has been reported. For this purpose, the three-dimensional Schrodinger equation has been solved numerically by the finite volume method for truncated pyramidal quantum dots as active regions taking into account all spontaneous and piezoelectric effects. To calculate the modal gain in the active region, the traveling-wave rate equations model has been used. We solved the traveling-wave equations coupled with the carrier density rate equation to obtain the output power related to the bias current, numerically. The output power is one of the parameters that describe the performance of a superluminescent light-emitting diode. The output power is studied for the SLEDs with different waveguide structural parameters such as the cavity length and radius of curvature. The temperature-dependent of the SLED output power is also investigated. The maximum output power of the SLED increased up to 0.08 W for the cavity with the length of 1200 μm.
M R Hareeshkumar, Shankaramurthy G J, A Alhadhrami, M R Jagadeesh, B M Prasanna
Published: 25 October 2021
Abstract:
A single crystal of nonlinear optical (NLO) of L-Alanine Trisodium Citrate (LATSC), an optically transparent crystal with a dimension 38×27×7mm3,was grown by way of solvent evaporation technique. Through the result of crystal diffraction, it is confirmed that LATSC fit into the noncentrosymetric orthorhombic space group crystal system. The W-H method was used to find the crystallographic distortion, crystalline size and strain using the powder diffraction results. The FTIR study proves the presence of necessary functional groups through their respective diverse modes of vibrations. The melting point of 265.9°C was noticed from thermal studies. The second harmonic generation (SHG) efficiency of LATSC is half of the reference KDP. The optical absorption study and associated optical parameters of the crystal were calculated using UV visible spectroscopy. The extended transparency for the incident light and the direct band gap of 4.23 eV along with the optical susceptibility of 3.519 were perceived. The hardness test revealed the considerable mechanical strength, moderate stiffness constant and yield strength of the crystal.
, Muthuganesan Rajendran
Published: 22 October 2021
Abstract:
Quantum decoherence happens when the system interacts with the environment. Quantum correlation behaviours in the two-qubit spin squeezing model are studied under the influence of intrinsic decoherence. Quantitative results were determined, which depend on parameters of the physical system by checking different quantifiers of quantum correlation such as entanglement, local quantum uncertainty, trace distance discord and uncertainty-induced quantum nonlocality. We show that the entanglement suffers from intrinsic decoherence and exhibits sudden death, whereas the other measures are more robust against intrinsic decoherence. Further, we highlight the role of spin squeezing coupling constant and magnetic field.
Published: 21 October 2021
Abstract:
We report on the derivation of the heat transport equation for nonmetals using a quantum Markovian master equation in Lindblad form. We first establish the equations of motion describing the time variation of the on-site energy of atoms in a one dimensional periodic chain that is coupled to a heat reservoir. In the continuum limit, the Fourier law of heat conduction naturally emerges, and the heat conductivity is explicitly obtained. It is found that the effect of the heat reservoir on the lattice is described by a heat source density that depends on the diffusion coefficients of the atoms. We show that the Markovian dynamics is equivalent to the long wavelength approximation for phonons, which is typical for the case of elastic solids. The high temperature limit is shown to reproduce the classical heat conduction equation.
Yinhua Cui, Shao-Hui Zhang, Qingshan Shi, Shengcai Hao, , Xiaobao Xie,
Published: 18 October 2021
Abstract:
A self-driven all-oxide β-Ga2O3/α-MoO3 heterojunction solar-blind ultraviolet (UV) photodetector is introduced in this work. The photodetector shows photo responsivity (R) of 0.59 mA/W, specific detectivity (D*) of 1011 Jones and linear dynamic region (LDR) of 162.9 dB at 10 V, and R of 0.26 mA/W, D* of 4×1010 Jones and LDR of 89.44 dB at -10 V. In addition, it could also operate repeatably and stably at zero bias, illustrating that it is a self-driven photodetector. In one word, the fabricated β-Ga2O3/α-MoO3 heterojunction has a potential to work as a self-driven solar-blind UV sensing device.
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