Scalable all-optical cold damping of levitated nanoparticles

TL;DR

This paper introduces a scalable all-optical cold damping method for levitated nanoparticles using programmable optical tweezers, achieving effective cooling and enabling advanced quantum control without electrodes or charged particles.

Contribution

The authors develop a novel all-optical, scalable cold damping technique using spatial modulation of optical traps, allowing independent control and cooling of multiple levitated particles.

Findings

Achieved cooling of nanoparticle motion down to 17 mK at low pressure.

Demonstrated simultaneous cooling of two particles.

Paved the way for quantum interactions and multipartite entanglement studies.

Abstract

The field of levitodynamics has made significant progress towards controlling and studying the motion of a levitated nanoparticle. Motional control relies on either autonomous feedback via a cavity or measurement-based feedback via external forces. Recent demonstrations of 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 a novel all-optical cold damping scheme based on spatial modulation of the trap position that is scalable to multiple particles. The scheme relies on using programmable optical tweezers to provide full independent control over trap frequency and position of each tweezer. We show that the technique cools the center-of-mass motion of particles down to $17\,$mK at a pressure of $2 \times 10^{-6}\,$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 3D quantum control of particle motion without cavity-based cooling, electrodes or charged particles, and probing multipartite entanglement in levitated optomechanical systems.