Visible quantum plasmonics from metallic nanodimers

TL;DR

This paper provides theoretical evidence that ultra-sub-wavelength metallic nanostructures can exhibit nonlinear quantum effects at the single plasmon level in the visible range, enabling nonclassical plasmonic behavior detectable with current technology.

Contribution

It demonstrates that weakly interacting nonlinear materials with localized plasmons can produce observable quantum nonlinear effects at the single plasmon level in visible frequencies.

Findings

Two-plasmon interaction energy is comparable to plasmon linewidths.

Localized surface plasmons can show sub-Poissonian correlations.

Proposed experimental configurations for detecting quantum effects.

Abstract

We report theoretical evidence that bulk nonlinear materials weakly interacting with highly localized plasmonic modes in ultra-sub-wavelength metallic nanostructures can lead to nonlinear effects at the single plasmon level in the visible range. In particular, the two-plasmon interaction energy in such systems is numerically estimated to be comparable with the typical plasmon linewidths. Localized surface plasmons are thus predicted to exhibit a purely nonclassical behavior, which can be clearly identified by a sub-Poissonian second-order correlation in the signal scattered from the quantized plasmonic field under coherent electromagnetic excitation. We explicitly show that systems sensitive to single-plasmon scattering can be experimentally realized by combining electromagnetic confinement in the interstitial region of gold nanodimers with local infiltration or deposition of ordinary nonlinear materials. We also propose configurations that could allow to realistically detect such an effect with state-of-the-art technology, overcoming the limitations imposed by the short plasmonic lifetime.