Effective Temperature in a Colloidal Glass

TL;DR

This study investigates the effective temperature of particles in a colloidal glass during the sol-gel transition, finding it matches the heat bath temperature despite complex particle dynamics.

Contribution

It introduces two passive rheology methods to measure effective temperature in colloidal glasses, confirming it equals the heat bath temperature during the transition.

Findings

Effective temperature equals the heat bath temperature within experimental error.

Observed long time correlations in particle dynamics during the transition.

Identified statistical properties of particle fluctuations during sol-gel transition.

Abstract

We study the Brownian motion of particles trapped by optical tweezers inside a colloidal glass (Laponite) during the sol-gel transition. We use two methods based on passive rheology to extract the effective temperature from the fluctuations of the Brownian particles. All of them give a temperature that, within experimental errors, is equal to the heat bath temperature. Several interesting features concerning the statistical properties and the long time correlations of the particles are observed during the transition.