Duke Physics Colloquium: Norbert Scherer (University of Chicago)

"Symmetry, Forces and Torques in the Dynamics and Excitations of Optical Matter" - Optical matter, collections of material particles that are bound together with light (electromagnetic fields), is readily formed in focused beams of light. Scattering between the constituent particle elements lead to spatial structuring of the total field by interference thereby establishing a natural length scale to the mesoscopic system. Our earlier work using (plasmonic) nanoparticles in solution, addressed the formation of optical matter utilizing the general optical beam shape, intensity and phase gradients and polarization for control. We recently demonstrated (ACS Nano, 2018) that the visualization of driven nanoparticle systems allow detailed trajectory studies of barrier crossing phenomena. This talk, based on recent publications in Nature Communications, Light: Science and Applications and Nano Letters, will focus on the self-motility and negative torque of optical matter dimers and arrays that arise due to symmetry breaking of the scattered fields and the asymmetry of the resultant induced moments and collective modes... See website for the rest of the abstract. Faculty host: Harold Baranger. Refreshments will be available before the event in room 130.