Vacuum-Induced Saturation in Plasmonic Nanoparticles

TL;DR

This paper demonstrates that quantum vacuum fluctuations can cause saturation effects in colloidal plasmonic nanostructures without requiring strong coupling, revealing a new influence of vacuum energy on nanoscale optical properties.

Contribution

It introduces the concept of vacuum-induced saturation (VISA) in colloidal nano-assemblies, showing vacuum fluctuations affect optical absorption without strong coupling.

Findings

Vacuum fluctuations cause saturation in dye molecules on plasmonic nanoparticles.

VISA occurs without the need for strong plasmon-exciton coupling.

Experimental spectra align with quantum optics models and electromagnetic simulations.

Abstract

Vacuum fluctuations are a fundamental feature of quantized fields. It is usually assumed that observations connected to vacuum fluctuations require a system well isolated from other influences. In this work, we demonstrate that effects of the quantum vacuum can already occur in simple colloidal nano-assemblies prepared by wet chemistry. We claim that the electromagnetic field fluctuations at the zero-point level saturate the absorption of dye molecules self-assembled at the surface of plasmonic nano-resonators. For this effect to occur, reaching the strong coupling regime between the plasmons and excitons is not required. This intriguing effect of vacuum-induced saturation (VISA) is discussed within a simple quantum optics picture and demonstrated by comparing the optical spectra of hybrid gold-core dye-shell nanorods to electromagnetic simulations.