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Proceedings Paper

Quantum interference of highly-dispersive surface plasmons (Conference Presentation)
Author(s): Yury S. Tokpanov; James S. Fakonas; Harry A. Atwater

Paper Abstract

Previous experiments have shown that surface plasmon polaritons (SPPs) preserve their entangled state and do not cause measurable decoherence. However, essentially all of them were done using SPPs whose dispersion was in the linear “photon-like” regime. We report in this presentation on experiments showing how transition to “true-plasmon” non-linear dispersion regime, which occurs near SPP resonance frequency, will affect quantum coherent properties of light. To generate a polarization-entangled state we utilize type-I parametric down-conversion, occurring in a pair of non-linear crystals (BiBO), glued together and rotated by 90 degrees with respect to each other. For state projection measurements, we use a pair of polarizers and single-photon avalanche diode coincidence count detectors. We interpose a plasmonic hole array in the path of down-converted light before the polarizer. Without the hole array, we measure visibility V=99-100% and Bell’s number S=2.81±0.03. To study geometrical effects we fabricated plasmonic hole arrays (gold on optically polished glass) with elliptical holes (axes are 190nm and 240nm) using focused ion beam. When we put this sample in our system we measured the reduction of visibility V=86±5% using entangled light. However, measurement using classical light gave exactly the same visibility; hence, this reduction is caused only by the difference in transmission coefficients of different polarizations. As samples with non-linear dispersion we fabricated two-layer (a-Si - Au) and three-layer (a-Si – Au – a-Si) structures on optically polished glass with different pitches and circular holes. The results of measurements with these samples will be discussed along with the theoretical investigations.

Paper Details

Date Published: 9 November 2016
PDF: 1 pages
Proc. SPIE 9921, Plasmonics: Design, Materials, Fabrication, Characterization, and Applications XIV, 99211P (9 November 2016); doi: 10.1117/12.2238282
Show Author Affiliations
Yury S. Tokpanov, California Institute of Technology (United States)
James S. Fakonas, California Institute of Technology (United States)
Harry A. Atwater, California Institute of Technology (United States)

Published in SPIE Proceedings Vol. 9921:
Plasmonics: Design, Materials, Fabrication, Characterization, and Applications XIV
Satoshi Kawata; Din Ping Tsai, Editor(s)

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