An apparatus for in-vacuum loading of nanoparticles into an optical trap

TL;DR

This paper presents a novel in-vacuum nanoparticle loading apparatus using a piezoelectric transducer, enabling efficient loading of various-sized particles into optical traps for advanced levitated optomechanics and sensing applications.

Contribution

The authors introduce a dry aerosol loading method that overcomes limitations of nebulizer-based techniques, allowing for rapid, high-vacuum compatible loading of diverse nanoparticle sizes into optical traps.

Findings

Successfully loaded particles from 170 nm to 10 μm into optical traps.

Generated accelerations of 10^7 g to overcome stiction forces.

Demonstrated potential for ultra-high-vacuum loading with laser feedback cooling.

Abstract

We describe the design, construction, and operation of an apparatus utilizing a piezoelectric transducer for in-vacuum loading of nanoparticles into an optical trap for use in levitated optomechanics experiments. In contrast to commonly used nebulizer-based trap-loading methods which generate aerosolized liquid droplets containing nanoparticles, the method produces dry aerosols of both spherical and high-aspect ratio particles ranging in size by approximately two orders of mangitude. The device has been shown to generate accelerations of order $10^7$ $g$, which is sufficient to overcome stiction forces between glass nanoparticles and a glass substrate for particles as small as $170$ nm diameter. Particles with sizes ranging from $170$ nm to $\sim 10$ $\mu$m have been successfully loaded into optical traps at pressures ranging from $1$ bar to $0.6$ mbar. We report the velocity distribution of the particles launched from the substrate and our results indicate promise for direct loading into ultra-high-vacuum with sufficient laser feedback cooling. This loading technique could be useful for the development of compact fieldable sensors based on optically levitated nanoparticles as well as matter-wave interference experiments with ultra-cold nano-objects which rely on multiple repeated free-fall measurements and thus require rapid trap re-loading in high vacuum conditions.