Effective temperature in a colloidal glass

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.

Keywords:

• effective temperature
• out of equilibrium systems
• colloids
• glasses
• optical trap
• Brownian motion
• passive and active rheology

Acknowledgements

This work has been partially supported by ANR-05-BLAN-0105-01.