arXiv subjects

Hemant Kumar Sharma

Publications and source records attributed to Hemant Kumar Sharma.

3 recordsLinked to original sources

arXiv2026

Geometry Induced Localization and Multifractality in Spiral quasiperiodic chain

We study a quasiperiodic Aubry Andre lattice arranged along a spiral curve. In this setup, the changing angle of the spiral naturally stretches and compresses the distances between neighboring sites, which in turn modulates the hopping amplitudes. The onsite potential itself remains the familiar AA form, but this geometry induced variation in the hopping dramatically changes how the system behaves both in its energy spectrum and in how its states localize.Using inverse participation ratios together with a full multifractal analysis, we find that curvature makes the system localize much more easily, even at relatively small quasiperiodic strengths. It also produces clear windows where the eigenstates become strongly multifractal. This shows that quasiperiodicity and geometry do not act independently rather, they reinforce one another in shaping the wavefunctions. Overall, we observe a smooth evolution of the states from extended, to multifractal, and finally to strongly localized. Our results pave the way for creating tunable quasiperiodic and geometry-driven localization effects in photonic waveguide arrays, ultracold atoms, mechanical metamaterials, and nanoscale platforms.

cond-mat.quant-gas↗

arXiv2025

Interplay of Electron Phonon Coupling Dissipative Phonon Bath and Electron Electron Interaction in a Triangular Quantum-Dot Trimer

Nonequilibrium charge transport through a trimer molecular transistor composed of three quantum dots arranged in a triangular geometry, which is placed on a substrate, has been studied in the presence of electron electron and electron phonon interactions. The entire system is described by an extended Anderson Holstein Caldeira Leggett Hamiltonian, in which the Caldeira Leggett term accounts for phonon damping arising from the coupling between the molecular vibrations and the substrate phonon bath. The electron phonon interaction is treated nonperturbatively using the Lang Firsov canonical transformation, while the electron electron interaction is incorporated at the mean field level. Keldysh nonequilibrium Greens function framework is used to study the transport properties, allowing us to calculate the spectral function, tunneling current, ad differential conductance of the trimer molecular transistor. The formalism enables systematic evaluation of the effects of Coulomb interaction, electron phonon coupling, and dissipation on the devices electronic transport characteristics.

cond-mat.mes-hall↗

arXiv2024

Emergent topological phases in an extended Su-Schrieffer-Heeger model with Rashba spin-orbit interaction, higher order hopping and domain wall

We theoretically investigate emergent topological phases in an extended spin-full Su-Schrieffer-Heeger (SSH) model considering Rashba spin-orbit interaction, all possible complex next to next nearest neighbor (NNNN) hopping preserving Chiral symmetry. Our analysis finds exact condition for which the topological phases of both the spin sectors could be independently varied. We show that it necessarily depends on complex NNNN only. We elaborate in detail the emergent topological phases, its criteria through analytic determination of non-trivial gap-closing condition due to the presence of $\cos 2k$ term. We also find that the profile of topological edge modes for finite winding numbers depend non-monotonously on the value of NNNN hopping elucidating competing effect of model parameters. We extend our study to few coupled chains and show explicitly that depending on the parameters all possible winding number ranging from zero to $2N$ could be obtained, where $N$ is the number of chains considered. Finally we incorporate the study of domain wall and remarkably we find that the location of mid-gap zero energy state by changing the values of model parameters. Our study could be of immensely useful for future applications in quantum technology.

cond-mat.mes-hall↗