Light-induced noise for tailoring temperature

We are interested in experimentally studying systems far from thermal equilibrium, in which the time scale of fluctuations is on the same order as that of the driving. To this end we realize a driven-dissipative model system, in which driving is done by tailored a-thermal random forces. Our system consists of an optically driven colloidal suspension. We treat the colloidal suspension as a second heat bath with an effective temperature (due to optical driving) that is coupled to an equilibrium heat bath (the suspending fluid). Here, we focus on quantifying the effective temperature of the colloidal bath as a function of the driving rate.

We find that depending on the sign of the optical forces and the frequency of their application we can tune the effective temperature from almost zero to four times the room temperature. We also show that the same effective temperature can be obtained for different dynamics.