Scalable all-optical cold damping of levitated nanoparticles

Motional control of levitated nanoparticles relies on either autonomous feedback via a cavity or measurement-based feedback via external forces. Recent demonstrations of the measurement-based ground-state cooling of a single nanoparticle employ linear velocity feedback, also called cold damping, and require the use of electrostatic forces on charged particles via external electrodes. Here we introduce an all-optical cold damping scheme based on the spatial modulation of trap position, which has the advantage of being scalable to multiple particles. The scheme relies on programmable optical tweezers to provide full independent control over the trap frequency and position of each tweezer. We show that the technique cools the centre-of-mass motion of particles along one axis down to 17 mK at a pressure of 2 x 10(-6) mbar and demonstrate its scalability by simultaneously cooling the motion of two particles. Our work paves the way towards studying quantum interactions between particles; achieving three-dimensional quantum control of particle motion without cavity-based cooling, electrodes or charged particles; and probing multipartite entanglement in levitated optomechanical systems. Optical traps equipped with a feedback system allow simultaneously cooling the motion of two particles.

Automated summary

This study introduces an all-optical cold damping scheme based on the spatial modulation of trap position, which allows for the cooling of levitated nanoparticles. The scheme is scalable and can cool multiple particles simultaneously. This work lays the foundation for studying quantum interactions between particles, achieving three-dimensional quantum control of particle motion, and probing multipartite entanglement.