# Model-free measurement of the pair potential in colloidal fluids using optical microscopy

## TL;DR

This paper introduces a simple, model-free method to measure pair potentials in colloidal fluids using optical microscopy, validated through simulations and experiments, facilitating better understanding of many-body interactions.

## Contribution

The paper presents a novel, model-free approach to determine pair potentials directly from particle-coordinate data, applicable to both simulations and experiments.

## Key findings

- Accurate measurement of pair potentials demonstrated in simulations.
- Successful application to experimental superparamagnetic colloids.
- Method enables investigation of many-body interactions.

## Abstract

We report a straightforward, model-free approach for measuring pair potentials from particle-coordinate data, based on enforcing consistency between the pair distribution function measured separately by the distance-histogram and test-particle insertion routes. We demonstrate the method's accuracy and versatility in simulations of simple fluids, before applying it to an experimental system composed of superparamagnetic colloidal particles. The method will enable experimental investigations into many-body interactions and allow for effective coarse-graining of interactions from simulations.