  We validate experimentally a fluctuation relation known as generalized
Jarzynski equality (GJE) governing the work distribution in a
feedback-controlled system. The feedback control is performed on a single
electron box analogously to the original Szilard engine. In GJE, mutual
information is treated on an equal footing with the thermodynamic work. Our
results clarify the role of the mutual information in thermodynamics of
irreversible processes.
