Experimental Test of a New Equality: Measuring Heat Dissipation in an   Optically Driven Colloidal System
  Measurement of energy dissipation in small nonequilibrium systems is generally a difficult task. Recently, Harada and Sasa [Phys.Rev.Lett. 95, 130602(2005)] derived an equality relating the energy dissipation rate to experimentally accessible quantities in nonequilibrium steady states described by the Langevin equation. Here, we show the first experimental test of this new relation in an optically driven colloidal system. We find that this equality is validated to a fairly good extent, thus the irreversible work of a small system is estimated from readily obtainable quantities. 
Shoichi Toyabe, Hong-Ren Jiang, Takenobu Nakamura, Yoshihiro Murayama,   and Masaki Sano