Imaging based feedback cooling of a levitated nanoparticle

Imaging-based detection of the motion of the levitated nanoparticles complements a widely-used interferometric detection method, providing a precise and robust way to estimate the position of the particle. Here, we show the camera-based feedback cooling of a charged nanoparticle levitated in a linear Paul trap. A charged nanoparticle levitated in a vacuum was observed by CMOS camera systems. The nanoparticle images were processed in realtime with a microcontroller integrated with a CMOS image sensor. The phase-delayed position signal was fed-back to one of the trap electrodes resulting in the velocity damping cooling. Our study provides a simple and versatile approach applicable for control of low-frequency mechanical oscillators.