Quantum limited particle sensing in optical tweezers

TL;DR

This paper demonstrates that spatial homodyne detection significantly enhances particle sensing sensitivity in optical tweezers compared to traditional quadrant detection, offering an order of magnitude improvement.

Contribution

It introduces an optimal particle sensing scheme based on spatial homodyne detection and develops a formalism for transverse spatial mode analysis.

Findings

Spatial homodyne detection outperforms quadrant detection in sensitivity.

Numerical simulations show an order of magnitude improvement.

The formalism enables better understanding of transverse spatial modes.

Abstract

Particle sensing in optical tweezers systems provides information on the position, velocity and force of the specimen particles. The conventional quadrant detection scheme is applied ubiquitously in optical tweezers experiments to quantify these parameters. In this paper we show that quadrant detection is non-optimal for particle sensing in optical tweezers and propose an alternative optimal particle sensing scheme based on spatial homodyne detection. A formalism for particle sensing in terms of transverse spatial modes is developed and numerical simulations of the efficacy of both quadrant and spatial homodyne detection are shown. We demonstrate that an order of magnitude improvement in particle sensing sensitivity can be achieved using spatial homodyne over quadrant detection.