LAUSR

Arrays of optically trapped nanoparticles have emerged as a platform for the study of complex nonequilibrium phenomena. Analogous to atomic many-body systems, one of the crucial ingredients is the ability to precisely control the interactions between particles. However, the optical interactions studied thus far only provide conservative optical binding forces of limited tunability. In this work, we exploit the phase coherence between the optical fields that drive the light-induced dipole-dipole interaction to couple two nanoparticles. In addition, we effectively switch off the optical interaction and observe electrostatic coupling between charged particles. Our results provide a route to developing fully programmable many-body systems of interacting nanoparticles with tunable nonreciprocal interactions, which are instrumental for exploring entanglement and topological phases in arrays of levitated nanoparticles. Description Levitated interactions The ability to trap macroscopic objects in vacuum, levitating them with optical fields and cooling them to their motional ground state provides access to highly sensitive sensors for applications in metrology. Rieser et al. demonstrate the trapping of two silica nanoparticles and explore the light-induced dipole-dipole interactions between them (see the Perspective by Pedernales). The results provide a route to developing a fully tunable and scalable platform to study entanglement and topological quantum matter with nanoscale objects. —ISO Optical trapping was used to explore the light-induced interactions between two silica nanoparticles.