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Random surface plasmon eigenmodes revealed

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Surface Plasmon (SP) eigenmodes of single metallic nanoparticles have spatial and spectral features which depend on the shape of the nanoparticle. For simple shapes, these properties follow clear trends with the size, constitutive material and dielectric environment of the nanoparticle which are now well-known. However, the situation is far more complex in disordered, or random metal-dielectric systems. A simple example of disordered medium is a semicontinuous metal film, obtained naturally when depositing some metal onto a dielectric substrate. Very broadband strong absorption features have been reported in semicontinuous metal films around the percolation threshold. Simple theoretical models related them to light induced randomly dispersed very intense electric fields named Hot Spots (HS). These HS were predicted to show peculiar properties, namely, a strong confinement, a random position over the substrate, and a strongly broadband character. Read more »

Spatially Resolved Quantum Nano-Optics of Single Photons Using an Electron Microscope

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We report on the experimental demonstration of single-photon state generation and characterization in an electron microscope. In this aim we have used low intensity relativistic (energy between 60 and 100 keV) electrons beams focused in a ca. 1 nm probe to excite diamond nanoparticles. This triggered individual neutral nitrogen-vacancy centers to emit photons which could be gathered and sent to a Hanbury Brown-Twiss intensity interferometer. The detection of a dip in the correlation function at small time delays clearly demonstrates antibunching and thus the creation of nonclassical light states. Specifically, we have also demonstrated single-photon states detection. We unveil the mechanism behind quantum states generation in an electron microscope, and show that it clearly makes cathodoluminescence the nanometer scale analog of photoluminescence. By using an extremely small electron probe size and the ability to monitor its position with subnanometer resolution, we also show the possibility of measuring the quantum character of the emitted beam with deep subwavelength resolution. Read more »

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