Symmetry Breaking in Non-Hermitian Plasmonic Lattices

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The Nobel Prize in Physics in 2016 was awarded to David J. Thouless, F. Duncan M. Haldane, and J. Michael Kosterlitz for theoretical discoveries of topological phase transitions and topological phases of matter. The term topology here refers to a property that remains intact when an object is stretched, twisted, or deformed. Topological materials that have previously been developed include topological insulators and topological photonic materials; such materials have potential to transform next-generation electronics and computers. The proposed experimental and theoretical work will focus on realizing topological plasmonic materials involving arrays of metal particles that may offer unprecedented functionality in a range of optoelectronic devices. Outreach efforts will integrate nanophotonics research advances into the classroom for freshman students and working with national organizations to promote science based on personal stories and public writing pieces.Topological photonics is an emerging area for realizing symmetry-protected properties at infrared and microwave wavelengths based on dielectric and magnetic materials but has had little connection to plasmonic materials. Hence, the effects of losses on properties such as topologically protected edges states are unknown. Moreover, recent advances in photonics theory suggest that such technologically interesting optical modes could be possible, and a major focus of this project is to determine whether topological edge states can be predicted using non-Hermitian models and realized experimentally in hybrid plasmonic lattices at visible wavelengths. The objectives include: (1) fabricating topological lattices based on deformed honeycomb lattices and investigating optical modes using non-Hermitian models and electrodynamics calculations that include higher multipoles; (2) realizing mechanically tunable topological lattices and establishing effects of distortions on switchable properties between trivial and topological states; (3) testing whether nanoparticle clusters that exhibit magnetic plasmon responses can support topological states; and (4) investigating whether plasmonic lattices with patterned regions of gain and tunable coupling strength can break parity-time symmetry.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.