# Direct Measurement of Kramers Turnover with a Levitated Nanoparticle

## TL;DR

This study provides the first direct experimental observation of the Kramers turnover phenomenon by measuring transition rates of a levitated nanoparticle in a bi-stable optical potential across different damping regimes.

## Contribution

The paper presents the first direct, quantitative experimental verification of the Kramers turnover using a levitated nanoparticle in a bi-stable optical trap.

## Key findings

- Measured transition rates across damping regimes
- Confirmed the theoretical Kramers turnover behavior
- Results agree with parameter-free analytical model

## Abstract

Understanding the thermally activated escape from a metastable state is at the heart of important phenomena such as the folding dynamics of proteins, the kinetics of chemical reactions or the stability of mechanical systems. In 1940 Kramers calculated escape rates both in the high damping and the low damping regime and suggested that the rate must have a maximum for intermediate damping. This phenomenon, today known as the Kramers turnover, has triggered important theoretical and numerical studies. However, to date there is no direct and quantitative experimental verification of this turnover. Using a nanoparticle trapped in a bi-stable optical potential we experimentally measure the nanoparticle's transition rates for variable damping and directly resolve the Kramers turnover. Our measurements are in agreement with an analytical model that is free of adjustable parameters.