# Radiative frequency shifts in nanoplasmonic dimers

## TL;DR

This paper investigates how electromagnetic environment-induced frequency shifts affect plasmonic resonances in nanoparticle dimers, revealing universal behavior and proposing experimental measurement methods.

## Contribution

It demonstrates that electromagnetic fluctuations cause significant shifts in nanoparticle dimer resonances, with a universal ratio dependent only on interparticle distance.

## Key findings

- Resonance frequency shifts are analogous to Lamb shifts in atomic physics.
- The ratio of level splitting for different modes is universal and depends only on distance.
- Proposes feasible experimental approaches using current nanoplasmonic technology.

## Abstract

We study the effect of the electromagnetic environment on the resonance frequency of plasmonic excitations in dimers of interacting metallic nanoparticles. The coupling between plasmons and vacuum electromagnetic fluctuations induces a shift in the resonance frequencies (analogous to the Lamb shift in atomic physics) which is usually not measurable in an isolated nanoparticle. In contrast, we show that this shift leads to sizable corrections to the level splitting induced by dipolar interactions in nanoparticle dimers. For the system parameters which we consider in this work, the ratio between the level splitting for the longitudinal and transverse hybridized modes takes a universal form dependent only on the interparticle distance and thus is highly insensitive to the precise fabrication details of the two nanoparticles. We discuss the possibility to successfully perform the proposed measurement using state-of-the-art nanoplasmonic architectures.