Nanoscale virtual potentials using optical tweezers

TL;DR

This paper demonstrates a method combining optical tweezers with feedback control to create customizable virtual potentials at nanoscale, enabling complex particle manipulations that surpass traditional optical trapping techniques.

Contribution

The authors introduce a feedback-based approach to generate arbitrary virtual potentials, including harmonic and double-well, at nanometer scales, enhancing control over colloidal particles beyond existing methods.

Findings

Successfully created virtual harmonic and double-well potentials.

Achieved virtual trapping at length scales down to 11 nm.

Enabled flexible manipulation of particle confinement and barrier heights.

Abstract

We combine optical tweezers with feedback to impose arbitrary potentials on a colloidal particle. The feedback trap detects a particle's position, calculates a force based on an imposed "virtual potential," and shifts the trap center to generate the desired force. We create virtual harmonic and double-well potentials to manipulate particles. The harmonic potentials can be chosen to be either weaker or stiffer than the underlying optical trap. Using this flexibility, we create an isotropic trap in three dimensions. Finally, we show that we can create a virtual double-well potential with fixed well separation and adjustable barrier height. These are accomplished at length scales down to 11 nm, a feat that is difficult or impossible to create with standard optical-tweezer techniques such as time sharing, dual beams, or spatial light modulators.