Abstract
In this talk, I will introduce a novel form of matter that consists of nanoparticles bound by light, referred to as “optical matter”. In optical matter systems, Newton’s third law can be violated because the system is open and the energy and momentum of the nanoparticles can be freely exchanged with the surrounding optical field. I will demonstrate that when optical matter is composed of two or more species of nanoparticles (different sizes or materials), the different species of particles interact with nonreciprocal interactions. This is realized in experiments as well as rigorous electrodynamic simulations, and a simple model for the nonreciprocal interactions is developed based on the phase relationship of induced dipoles.
In the thermodynamic limit (very large number of nanoparticles), optical matter can be expected to behave as a material that can undergo phase transitions. Using the theoretical model, I demonstrate that such phase transitions can be observed in two distinct ways: (1) by increasing the optical power density, thereby increasing the strength of the interactions, or (2) by increasing the strength of the nonreciprocal interactions using the phase of the induced dipoles.