The Birth of a Plasmonic Topological Quasiparticle on the Nanofemto Scale

TL;DR

This paper reports the creation and imaging of a new plasmonic topological quasiparticle with spin angular momentum texture on the nanofemto scale, revealing ultrafast topological phenomena at the interface of classical and quantum physics.

Contribution

It introduces a novel topological quasiparticle formed by optical field-electron interactions, characterized by a unique spin texture and ultrafast dynamics, created in a nanostructured silver film.

Findings

Identification of a plasmonic vortex with a meron-like spin texture

Ultrafast imaging of electromagnetic wave propagation at 255 nm/fs

The quasiparticle exhibits topological and symmetry-breaking properties

Abstract

At interface of the classical and quantum physics Maxwell and Schr\"odinger equations describe how optical fields drive and control electronic phenomena at THz or PHz frequencies and on ultra-small scales to enable lightwave electronics. Light striking a metal surface triggers electric field-electron particle/wave interactions to coherently imprint and transfer its attributes on the attosecond time scale. Here we create and image by ultrafast photoemission electron microscopy a new quasiparticle of optical field-collective electron interaction where the design of geometrical phase creates a plasmonic topological spin angular momentum texture. The spin texture resembles that of magnetic meron quasiparticle, is localized within 1/2 wavelength of light, and exists on ~20 fs (2^10-14 s) time scale of the plasmonic field. The quasiparticle is created in a nanostructured silver film, which converts coherent linearly polarized light pulse into an evanescent surface plasmon polariton light-electron wave with a tailored geometric phase to form a plasmonic vortex. Ultrafast coherent microscopy imaging of electromagnetic waves propagating at the local speed of light of 255 nm/fs, electromagnetic simulations, and analytic theory find a new quasiparticle within the vortex core, with topological spin properties of a meron that are defined by the optical field and sample geometry. The new quasiparticle is an ultrafast topological defect whose chiral field breaks the time-inversion symmetry on the nanoscale; its creation, symmetry breaking topology, and dynamics pertain to contexts ranging from the cosmological structure creation to topological phase transitions in quantum liquids and gases, and may act as a transducer for quantum information on the nanofemto scale.