arXiv subjects

Kelvin Dsouza

Publications and source records attributed to Kelvin Dsouza.

3 recordsLinked to original sources

arXiv2026

Magneto-optical characterization of GeSn and GeSn/SiGeSn heterostructures

Hole spin qubits in germanium (Ge)-based heterostructures have demonstrated their potential for scalable quantum information processing using all-electrical gate operations. Furthermore, the emerging material platform of germanium-tin (GeSn) can feature a direct bandgap, which makes it promising for establishing spin-photon interfaces for quantum networking. Here, we perform magneto-photoluminescence measurements of a Ge0.88Sn0.12/Si0.02Ge0.89Sn0.09 double quantum well using the double modulation Fourier transform infrared-based photoluminescence spectroscopy. Our measurements reveal theoretically expected diamagnetic shift at low magnetic fields as well as the linear trend of zeroth-level Landau quantization at higher fields and Zeeman-induced polarization-dependent energy shifts at +/- 12 T. We extract an effective g-factor of ~ 2 and an excitonic reduced mass of ~ 0.04 me consistent with previous estimations for heavy-hole Γ-valley excitons. The observation of sizable Zeeman splitting is consistent with strong spin-orbit interaction in Ge-based hole systems, which can enable electrically driven spin control. Our analysis can be adopted for studying and evaluating group-IV semiconductor heterostructures as hosts for hole spin qubits toward scalable quantum information processing.

quant-ph↗

arXiv2025

Heavy Hole vs. Light Hole Spin Qubits: A Strain-Driven Study of SiGe/Ge and GeSn/Ge

This work investigates and compares the impact of strain on heavy hole (HH) spin qubits in SiGe/Ge and light hole (LH) spin qubits in GeSn/Ge heterostructures, focusing on energy states, g-factor, Rabi frequency, spin relaxation, and dephasing times. By exploring the distinct properties of HH and LH spin qubits under strain, we demonstrate how strain serves as a tunable parameter to optimize qubit performance. The study highlights that LH spin qubits in Ge quantum dots exhibit lower relaxation rates and higher Rabi frequencies, offering significant advantages for addressing current challenges in gate-defined spin qubits. A significant difference is observed in the g-factor anisotropy, where for HHs the out-of-plane g-factor is larger than the in-plane g-factor, whereas for LHs, the in-plane g-factor dominates both in GeSn/Ge and SiGe/Ge quantum dots. This comparative analysis provides a deeper understanding of HH and LH spin dynamics, advancing the development of scalable quantum technologies based on strained Ge systems.

cond-mat.mes-hall↗

arXiv2022

EMReact: A Tool for Modelling Electromagnetic Field Induced Effects in Chemical Reactions by Solving the Discrete Stochastic Master Equation

The effects of electromagnetic fields (EMF) have been widely debated concerning their role in chemical reactions. Reactions usually took hours or days to complete, and have been shown to happen a thousand times faster using EMF radiations. This work develops a formalism and a computer program to evaluate and quantify the EMF effects in chemical reactions. The master equation employed in this program solves the internal energy of the reaction under EMFs while including collisional effects. Multiphoton absorption and emission are made possible with the transitioning energy close to the EMF and are influenced by the dielectric properties of the system. Dimethyl Sulfoxide and Benzyl Chloride are simulated under different EMF intensities. The results show that EMF absorption is closely related to the collisional redistribution of energy in molecules. The EMF effect can be interpreted as a shift of the thermodynamic equilibrium. Under such nonequilibrium energy distribution, the "temperature" is not a reliable quantity for defining the state of the system.

physics.chem-ph↗