Plasmonic Nanoantenna Array Metasurfaces and Colloidal Nanoparticles for Single-Photon Source Applications

Jerome Brone

Advised by Svetlana Lukishova

Background

Single-photon sources are important components in quantum communications systems. Although secure quantum communication can be achieved over short distances with classical sources, single-photon sources are essential for long-distance quantum communication due to losses in communication channels. Using single-photon sources, quantum repeaters can be used to transmit signals over long distances. For quantum repeater protocols, single photons must be indistinguishable. Photon indistinguishability is hard to achieve at room temperature. Many single-photon emitters are in the visible spectral range, and so narrow resonances must be achieved in that range as well.

Out of all the plasmonic nanostructures, the highest increase in emission rate and enhancement in fluorescence intensity were achieved using metal plasmonic patch nanoantennas, in which an emitter is placed in a nanoscale dielectric gap between a metal mirror and a metal nanoparticle. Plasmonic nanoantenna array metasurfaces which product narrow resonances may be used to make the linewidth of the photons narrow. Plasmonic patch nanoantennas as elements of such arrays can both enhance the emission rates of the photons and cause the linewidth to be narrow. The goal of my research is to model and investigate plasmonic nanoantenna array metasurfaces with narrow resonances in the visible range, as well as investigate plasmonic nanoparticles which can be used for nanopatch antennas.

Objective

Modeling and investigating plasmonic nanoantenna array metasurfaces and colloidal plasmonic nanoparticles towards creation of indistinguishable single photons.

Numerical modeling of plasmonic nanoantenna array metasurface with very narrow lattice resonance in visible spectral range.
Examination of colloidal plasmonic nanoparticles, nanoantenna array metasurfaces, and emitter nanocrystals with atomic force microscopy.
Fluorescent and spectral measurements of colloidal plasmonic nanoparticles, single emitters and emitters with plasmonic nanoantenna array metasurfaces.

Single Emitter Samples

Characterizing Plasmonic Nanostructures

Atomic force microscopy scan of the 100 nm silver nanocubes

Atomic force microscopy scans of the nanoantenna array

Fluorescence time trace of silver nanocubes displaying fluorescence spikes

Fluorescence time trace of silver nanocubes displaying stepwise photoluminescence

Image and graph of the spectrum of the silver nanocubes in PVP

Video of silver nanocube spectra changing in time (5 s exposure time)

Characterizing Single-Photon Emitters

Video of blinking NQD’s

Raster scan fluorescence image of 640 nm maximum fluorescence NQD

Raster scan fluorescence image of 800 nm maximum fluorescence NQD

Raster scan fluorescence image of 20 nm diameter NV-center nanodiamond

Spectrum of the 642 nm maximum fluorescence NQD

Numerical Modeling of Plasmonic Nanoantenna Array Metasurfaces

Simulation of array in glass, with resonance near fluorescence wavelength of NQD

Simulation of array in glass, with resonance near fluorescence wavelength of NV-center
nanodiamond

Transmission and reflection data using dipole source

Conclusion

Characterization of emitters and nanostructures through spectral imaging, fluorescence, and atomic force microscopy
Observation of unusual intensity spikes and stepwise change in photoluminescence
Change in time of photoluminescence spectra of silver nanocubes with Raman scattering
Simulated narrow resonance at NQD wavelength and wide resonance at nanodiamond wavelength
Observed independence of resonance position on array element material
Gathered electric field and Purcell factor data using simulated dipole source