Title: Dynamic particle tracking reveals the aging temperature of a colloidal glass

Author (Talk): Chaoming Song, City College of New York

Abstract:

We investigate the autocorrelation function and the response function to external fields to monitor the aging of a highly concentrated colloidal glass. At equilibrium, all the observables are stationary while in the out-of-equilibrium glassy state they have an explicit dependence on the age of the system. Indeed, we find that the transport coe±cients scale with the aging time as a power law, a signature of the slow relaxation of the system. Nevertheless, our analysis reveals that the glassy system has thermalized at a constant temperature independent of the age of the system. This temperature is larger than the bath and it re°ects the slow structural rearrangements associ- ated with cage dynamics. A universal scaling law is found to describe not only the dynamics of the global quantities but also the local °uctuations of the observables. While our general results can be interpreted within the framework of unifying formulations of aging in spin-glasses, the observed scaling forms of the observables do not conform to the theoretical predictions.