International Journal of Physics

International Journal of Physics | Vol. 5, No. 6, June 2014 | pp. 41–48

DOI: 10.46882/2014/IJP/000050

Research Article

Title: Squeezed Vacuum State Transport and Decoupling Metrics in Periodic Optical Waveguide Networks

Names of Authors: A. M. Ross¹, F. Z. Al-Mansoori²

Authors’ Affiliations: ¹Department of Physics, University of Queensland, Brisbane, QLD 4072, Australia; ²Department of Physics, Faculty of Science, United Arab Emirates University, Al Ain, United Arab Emirates

Abstract: Processing non-classical states of light within integrated photonic architectures is essential for scalable quantum communication and computation networks. This study analyzes the transport properties and evaluates decoupling metrics of continuous-wave squeezed vacuum states propagating through a periodic array of coupled optical waveguides. We solved the spatial quantum stochastic Schrödinger equations using an algebraic operator framework that accounts for localized evanescent coupling and intrinsic propagation losses. Squeezed vacuum states at 1550.0 nm were injected into the central waveguide channel of a lithium niobate array. The calculations show that spatial discrete diffraction spreads quantum correlations across adjacent channels, which reduces the squeezing level in the primary channel from 6.0 dB to 1.8 dB over a 20.0 mm propagation path. To counteract this loss of squeezing, we simulated an array configuration with a linearly chirped coupling profile. This design establishes a quantum Bloch oscillation regime that successfully restores the squeezing level to 5.2 dB at the output facet. This restoration achieves a state fidelity calculation of 94.2% ± 0.4%. These results provide practical strategies for routing and protecting non-classical light within complex quantum photonic integrated circuits.

Keywords: Quantum optics; squeezed states; optical waveguides; discrete diffraction; Bloch oscillations; integrated photonics

Manuscript Timeline: Received: March 04, 2014; Revised: April 22, 2014; Accepted: May 12, 2014; Published: June 19, 2014

Citation: Ross, A. M., & Al-Mansoori, F. Z. (2014). Squeezed Vacuum State Transport and Decoupling Metrics in Periodic Optical Waveguide Networks. International Journal of Physics, 5(6), 41–48.

International Journal of Physics | Vol. 5, No. 5, May 2014 | pp. 33–40

DOI: 10.46882/2014/IJP/000049

Research Article

Title: Resonant Energy Transfer Dynamics between Colloidal Quantum Dots and Monolayer Transition Metal Dichalcogenides

Names of Authors: T. H. Nguyen¹, C. M. Brauer²

Authors’ Affiliations: ¹Department of Physics, Vietnam National University, Hanoi 100000, Vietnam; ²Institut für Physik, Humboldt-Universität zu Berlin, 12489 Berlin, Germany

Abstract: Hybrid semiconductor nanostructures combining zero-dimensional and two-dimensional materials provide new opportunities for developing advanced light-harvesting systems. This paper examines the non-radiative Förster resonant energy transfer (FRET) dynamics between colloidal cadmium selenide (CdSe) quantum dots and monolayer tungsten diselenide (WSe²). The hybrid interfaces were fabricated via sequential spin-coating routines onto quartz substrates. We performed steady-state photoluminescence and time-resolved single-photon counting measurements at 300 K. The experimental data reveal a strong 78.0% quenching of the quantum dot photoluminescence emission when coupled to the WSe² monolayer. Concurrently, the average fluorescence lifetime of the CdSe quantum dots decreased from 4.8 ns to 1.05 ns. This lifetime reduction yields a calculated FRET efficiency of 78.1% with a corresponding energy transfer rate of 0.74 ns⁻¹. The donor-acceptor separation distance was estimated to be 4.2 nm using the standard Förster mathematical model. Spectral overlap analysis confirms that energy transfer is mediated by the alignment between quantum dot emission and the WSe² exciton absorption bands. These rapid energy transfer dynamics show that quantum dot sensitization can significantly enhance light absorption in ultra-thin optoelectronic architectures.

Keywords: Quantum dots; transition metal dichalcogenides; resonant energy transfer; fluorescence lifetime; hybrid nanostructures; optoelectronics

Manuscript Timeline: Received: February 12, 2014; Revised: March 26, 2014; Accepted: April 15, 2014; Published: May 16, 2014

Citation: Nguyen, T. H., & Brauer, C. M. (2014). Resonant Energy Transfer Dynamics between Colloidal Quantum Dots and Monolayer Transition Metal Dichalcogenides. International Journal of Physics, 5(5), 33–40.

International Journal of Physics | Vol. 5, No. 4, April 2014 | pp. 25–32

DOI: 10.46882/2014/IJP/000048

Research Article

Title: Density Functional Theory Analysis of Catalytic Carbon Dioxide Reduction on Nitrogen-Doped Graphene Surfaces

Names of Authors: A. L. Silva¹, K. N. Gupta²

Authors’ Affiliations: ¹Institute of Physics, Federal University of Rio Grande do Sul, Porto Alegre 91501-970, Brazil; ²Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India

Abstract: Electrochemical reduction of carbon dioxide (CO²) into valuable chemical feedstocks offers a sustainable strategy for carbon recycling. This investigation uses density functional theory calculations to analyze the catalytic performance and reaction mechanisms of CO² reduction on nitrogen-doped graphene surfaces. We modeled three distinct configurations: pyridinic, pyrrolic, and quaternary nitrogen doping. Free energy profiles for intermediate steps leading to formic acid (HCOOH) and carbon monoxide (CO) were computed using the computational hydrogen electrode model. The calculations demonstrate that pyridinic nitrogen sites lower the activation barrier for the initial protonation step (*CO² + H⁺ + e⁻ -> *COOH) to 0.45 eV. This value is significantly lower than the 1.15 eV barrier calculated for pristine graphene surfaces. The overpotential required to trigger selective formic acid production on pyridinic sites was estimated at -0.38 V versus the standard hydrogen electrode. Charge density difference mappings show that nitrogen doping induces localized spin polarization and electron deficiency on adjacent carbon atoms. This electronic reconfiguration stabilizes the adsorbed intermediates. These quantum mechanical insights provide theoretical guidelines for developing metal-free, carbon-based catalysts for efficient greenhouse gas conversion.

Keywords: Carbon dioxide reduction; density functional theory; nitrogen-doped graphene; electrocatalysis; reaction mechanism; overpotential

Manuscript Timeline: Received: January 05, 2014; Revised: February 17, 2014; Accepted: March 04, 2014; Published: April 10, 2014

Citation: Silva, A. L., & Gupta, K. N. (2014). Density Functional Theory Analysis of Catalytic Carbon Dioxide Reduction on Nitrogen-Doped Graphene Surfaces. International Journal of Physics, 5(4), 25–32.

International Journal of Physics | Vol. 5, No. 3, March 2014 | pp. 17–24

DOI: 10.46882/2014/IJP/000047

Research Article

Title: Finite Element Modeling of Acoustic Wave Scattering in Saturated Porous Media with Viscoelastic Inclusions

Names of Authors: P. J. O’Connor¹, S. B. Mukherjee²

Authors’ Affiliations: ¹Department of Civil and Environmental Engineering, University College Cork, Cork, Ireland; ²Department of Physics, Indian Institute of Technology Kharagpur, West Bengal 721302, India

Abstract: Characterizing elastic wave propagation through fluid-saturated porous structures is crucial for geophysical exploration and modern acoustic dampening designs. This study presents a finite element modeling approach to simulate acoustic wave scattering within a saturated porous matrix containing distributed viscoelastic inclusions. The mathematical model integrates Biot's dynamic equations of poroelasticity with a generalized Maxwell constitutive framework to account for viscoelastic relaxation. Numerical simulations were executed across an ultrasonic frequency spectrum from 10.0 kHz to 500.0 kHz. The computational results demonstrate that the presence of viscoelastic inclusions induces a strong attenuation peak for the fast compressional wave mode at 150.0 kHz. This attenuation is primarily driven by local fluid flow mechanisms at the matrix-inclusion interfaces. The scattering cross-section displays a non-linear dependence on inclusion volume fractions, showing saturation behavior above a 15.0% threshold. Experimental validation was conducted using synthetic porous sandstone specimens filled with silicone rubber nodules. The measured transmission loss spectra matched the simulated profiles within a ±5.5% margin. These findings help optimize acoustic barriers and improve interpretations of seismic data collected from fluid-bearing geological formations.

Keywords: Porous media; acoustic scattering; finite element modeling; Biot's theory; viscoelasticity; wave attenuation

Manuscript Timeline: Received: December 10, 2013; Revised: January 20, 2014; Accepted: February 08, 2014; Published: March 12, 2014

Citation: O’Connor, P. J., & Mukherjee, S. B. (2014). Finite Element Modeling of Acoustic Wave Scattering in Saturated Porous Media with Viscoelastic Inclusions. International Journal of Physics, 5(3), 17–24.

International Journal of Physics | Vol. 5, No. 2, February 2014 | pp. 9–16

DOI: 10.46882/2014/IJP/000046

Research Article

Title: Fluid Velocity Mapping and Magnetic Reconnection Rates in the Solar Corona via Extreme Ultraviolet Imaging

Names of Authors: G. R. Davies¹, M. T. Al-Saeed²

Authors’ Affiliations: ¹School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, United Kingdom; ²Department of Physics, Faculty of Science, Kuwait University, Safat 13060, Kuwait

Abstract: Magnetic reconnection drives explosive energy release events in the solar atmosphere, accelerating particles and heating plasma to millions of Kelvin. This paper analyzes fluid velocity mapping and quantifies local magnetic reconnection rates within a solar flare event observed in the solar corona. We utilized high-resolution data from space-based extreme ultraviolet (EUV) imaging channels tracking iron ion emission lines (Fe XIV and Fe XVI). Differential affine velocity estimator algorithms were deployed to construct two-dimensional velocity fields of plasma inflows and outflows near the reconnection site. The empirical measurements reveal systematic plasma inflows moving at 15.4 km/s, while directed outflows reach velocities of 245.0 km/s. Based on these transport metrics, the local dimensionless reconnection rate was calculated to range between 0.05 and 0.08. These values closely align with fast reconnection regimes predicted by the Petschek theoretical framework. Spectroscopic line-broadening analysis indicates localized turbulent temperatures peaking at 8.5 MK within the current sheet boundary. This high temperature confirms intense localized viscous dissipation. These imaging diagnostics provide direct observational constraints for refining magnetohydrodynamic models of coronal heating mechanisms.

Keywords: Solar corona; magnetic reconnection; extreme ultraviolet; plasma dynamics; solar flares; magnetohydrodynamics

Manuscript Timeline: Received: November 05, 2013; Revised: December 18, 2013; Accepted: January 10, 2014; Published: February 14, 2014

Citation: Davies, G. R., & Al-Saeed, M. T. (2014). Fluid Velocity Mapping and Magnetic Reconnection Rates in the Solar Corona via Extreme Ultraviolet Imaging. International Journal of Physics, 5(2), 9–16.

International Journal of Physics | Vol. 5, No. 1, January 2014 | pp. 1–8

DOI: 10.46882/2014/IJP/000045

Research Article

Title: Optical Properties and Exciton Dynamics of Monolayer Molybdenum Disulfide on Flexible Substrates

Names of Authors: Y. S. Kim¹, J. L. Vigneron²

Authors’ Affiliations: ¹Department of Physics and Astronomy, Seoul National University, Seoul 08826, South Korea; ²Laboratoire de Physique du Solide, Facultés Universitaires Notre-Dame de la Paix, B-5000 Namur, Belgium

Abstract: Monolayer transition metal dichalcogenides have gained significant attention due to their direct bandgap properties and potential for flexible optoelectronic applications. This study characterizes the optical properties and exciton dynamics of monolayer molybdenum disulfide (MoS²) transferred onto flexible polyethylene terephthalate substrates. The monolayer flakes were synthesized via chemical vapor deposition and verified using micro-Raman spectroscopy. Photoluminescence measurements were performed under mechanical tensile strains varying from 0.0% to 2.0% at room temperature. The unstrained monolayer exhibits a strong photoluminescence peak at 1.85 eV, corresponding to the direct A-exciton transition. Applying a 1.5% tensile strain induces a systematic redshift in the exciton peak to 1.76 eV, yielding a strain gauge factor of 60.0 meV/% strain. Time-resolved photoluminescence spectroscopy revealed a multi-exponential exciton decay profile. The fast decay component, associated with defect-mediated non-radiative recombination, decreased from 18.5 ps to 11.2 ps under maximum strain conditions. This change indicates a strain-induced increase in defect capture cross-sections. Our calculations show that mechanical strain effectively tunes the spin-orbit splitting at the valence band extrema. These experimental findings offer valuable insights for engineering tunable light-emitting devices and flexible optical sensors.

Keywords: Molybdenum disulfide; flexible substrates; photoluminescence; exciton dynamics; tensile strain; transition metal dichalcogenides

Manuscript Timeline: Received: October 14, 2013; Revised: November 25, 2013; Accepted: December 12, 2013; Published: January 15, 2014

Citation: Kim, Y. S., & Vigneron, J. L. (2014). Optical Properties and Exciton Dynamics of Monolayer Molybdenum Disulfide on Flexible Substrates. International Journal of Physics, 5(1), 1–8.