Pooja Sudha | Searcharxiv

arXiv2025

Quantum Coulomb Blockade in Orbital Resolved Phosphorus Triple-Donor Molecule

Multi-donor architecture in silicon offers a promising direction towards scalable solid-state qubits and quantum technologies operating at practical conditions. However, the overlap of multiple donor wave-functions develops a complex internal electronic configuration with several discrete energy levels. Probing these discrete-correlated states is essential for understanding inter-donor coupling and exchange interactions towards their practical implementations in quantum-technologies. We have experimentally demonstrated quantum Coulomb blockade mediated systematic filling of several electrons into orbital-resolved molecular states within multi-phosphorous-donor molecules accompanied by a correlated decrement in charging energies for higher hybridized orbitals due to expanded Bohr radii and electron delocalization. Corresponding, first-principle density functional theory calculations offer microscopic insight into the orbital configurations, while the rate equation simulations of quantum Coulomb blockade faithfully reproduce the experimental stability diagrams. This comprehensive characterization advances and discusses the role of donor-molecules in silicon in scalable building blocks for quantum technologies operable at elevated temperatures.

cond-mat.mes-hall↗

arXiv2024

Large-Scale Cost-Effective Mid-Infrared Resonant Silicon Microstructures for Surface-Enhanced Infrared Absorption Spectroscopy

The mid-infrared region is crucial for elucidating the unique biochemical signatures of microorganisms. The MIR resonant structures turned out to facilitate exceptional performance owing to the enhance electric field confinement in the nano-sized aperture. However, the extension of such technique in bacteria-sensing remains limited, primarily due to its micrometre size. This work is the first demonstration of a MIR resonant structure, the gold-coated micro-structured inverted pyramid array of silicon exhibiting light-trapping capabilities, for the bacteria detection in entire MIR range. The electric-field localization within the micro-sized cavity of inverted pyramid amplifies the light-matter interaction by harnessing surface plasmon polaritons, leading to improved detection sensitivity. The confinement of electric field is further corroborated by electric-field simulations based on finite element method. In particular, we observed notable enhancement in both the quantitative and qualitative detection of Escherichia coli and Staphylococcus aureus for the bacteria cell with very low concentration, reflecting the efficacy of our detection method. Furthermore, the cost-effective micro structured silicon is fabricated using metal-assisted chemical etching method with the lithography-free method, along with the capabilities of wafer-scale fabrication. Moreover, our device configuration even demonstrates the characteristics of reusability and reproducibility offers substantial benefits over conventional detection schemes. Consequently, this CMOS technology-compatible biosensor signifies promising ways for the integration of this technology with forthcoming bio-applications.

cond-mat.mes-hall↗