Spontaneous continuous orbital motion of nanoparticles levitated in air

摘要： We report on the discovery of a unidirectional continuous orbital motion of nanoparticles which occurs spontaneously in room-temperature air and can be manipulated by light. Trapped nanoparticles exhibit a transition between Brownian particles in two separate lattice sites and orbiting particles in a single lattice site. The orbital motion is sensitive to air pressure and is vanishing at low pressure, suggesting that the orbital motion is supported by air. Our results pave the way for manipulating nanoscale objects on the basis of their cooperative dynamics.