Light-driven nanodrones based on optical spin-orbit locking

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Can we devise multi-functional nano-objects with typical dimensions of a few wavelengths of visible light that can be propelled and steered in liquids in 3D with nanometer precision just by illuminating them with unfocused light beams of circular polarization? In the present project we will develop such capability by making use of tailor-made plasmonic nano-structures, so-called plasmonic nanomotors. Plasmonic nanomotors are designed to exhibit directional resonant scattering that depends strongly on the incident photon spin, similar as in optical spin-orbit locking. We will employ a whole set of such plasmonic nanomotors positioned on microscopic transparent solid supports. By means of their arrangement and actuation pattern it will be possible to implement all necessary degrees of freedom, like forward-backward, left-right, up-down, yaw, pitch, and eventually also roll, which shall be fully controlled and feedback-stabilized – much similar as in the versatile macroscopic multirotor drones. Feedback stabilization will provide the possibility to largely counter-act Brownian motion and thereby will enable nanometer-precise actuation. Our approach will provide a general method to control the movement of wavelength-sized vehicles in liquid environments – so-called nanodrones - that may combine different functionalities, such as a probing section in addition to a section responsible for propulsion and steering. This provides the basis for novel types of experiments, e.g. in the life sciences for investigations and manipulations at the surface or within living cells, or for the transport and processing of functional cargo attached to such nanodrones. In particular, nanometer-precise control of all degrees of freedom will finally provide a platform to perform scanning-probe-type experiments, e.g. tip-enhanced spectroscopy of liquid-solid interfaces or to exert controlled local forces.