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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 20: Poster: Colloids and Complex Liquids

CPP 20.13: Poster

Dienstag, 12. März 2013, 18:15–20:15, Poster C

Noninvasive measurement of dissipation in colloidal systems — •Jakob Mehl¹, Boris Lander², Udo Seifert², and Clemens Bechinger^{1, 3} — ¹2. Physikalisches Institut, Universität Stuttgart, Germany — ²II. Institut für Theoretische Physik, Universität Stuttgart, Germany — ³Max-Planck-Institute for Intelligent Systems, Stuttgart, Germany

According to Harada and Sasa [Phys. Rev. Lett. 95, 130602 (2005)], heat production generated in a nonequilibrium steady state can be inferred from measuring response and correlation functions. In many colloidal systems, however, it is a nontrivial task to determine response functions, whereas details about spatial steady state trajectories are easily accessible. Using a simple conditional averaging procedure, we show how this fact can be exploited to reliably evaluate average heat production. By combining paramagnetic colloidal particles, rotating laser tweezers and digital video microscopy, we apply the new method to two nonequilibrium steady states, which can be coupled by an externally controlled magnetic field. We show, that the average heat production is nonmonotonic in the coupling strength and even for low statistics quite robust results are available [Phys. Rev. E. 86, 030401(R) (2012)].