Arrested rotation of plasmonic optical matter driven by chiral light

Abstract

Plasmonic optical matter (OM), composed of optically bound metallic nanoparticles, can be driven into stable rotation by harvesting the spin angular momentum (SAM) of chiral light. This study demonstrates a reversible rotational jamming transition in assemblies of 400nm gold nanoparticles confined within a focused, circularly polarized laser beam. While assemblies with well-defined hexagonal symmetry efficiently convert SAM into orbital motion, breaking symmetry leads to a loss of rotation. We corroborate our results with numerical simulations. These results establish structural symmetry as a primary control parameter for angular-momentum dissipation in driven micromechanical systems. Our findings offer a unique platform for studying universal kinetic arrest and provide a framework for developing reconfigurable light-driven micromachines and soft robotics.