Real-Time Quantum Dynamics of Long-Range Electronic Excitation Transfer in Plasmonic Nanoantennas

TL;DR

This paper uses real-time quantum dynamics calculations to analyze electronic excitation transfer in plasmonic nanoantennas, revealing long-range couplings beyond traditional models and emphasizing the importance of quantum effects in designing light-harvesting systems.

Contribution

It introduces a quantum-mechanical, real-time approach to characterize EET in plasmonic systems, showing long-range couplings and limitations of classical FRET models.

Findings

Long-range electronic couplings exceed FRET cutoff limits.

Coherent oscillations of conduction electrons cause extended EET range.

Nearest-neighbor FRET models are inadequate for plasmonic systems.

Abstract

Using large-scale, real-time quantum dynamics calculations, we present a detailed analysis of electronic excitation transfer (EET) mechanisms in a multi-particle plasmonic nanoantenna system. Specifically, we utilize real-time, time-dependent, density functional tight binding (RT-TDDFTB) to provide a quantum-mechanical description (at an electronic/atomistic level of detail) for characterizing and analyzing these systems, without recourse to classical approximations. We also demonstrate highly long-range electronic couplings in these complex systems and find that the range of these couplings is more than twice the conventional cutoff limit considered by FRET based approaches. Furthermore, we attribute these unusually long-ranged electronic couplings to the coherent oscillations of conduction electrons in plasmonic nanoparticles. This long-range nature of plasmonic interactions has important ramifications for EET - in particular, we show that the commonly used "nearest-neighbor" FRET model is inadequate for accurately characterizing EET even in simple plasmonic antenna systems. These findings provide a real-time, quantum-mechanical perspective for understanding EET mechanisms and provide guidance in enhancing plasmonic properties in artificial light-harvesting systems.