  Recent progress on micro- and nanometer scale manipulation has opened the
possibility to probe systems small enough that thermal fluctuations of energy
and coordinate variables can be significant compared with their mean behavior.
We present an experimental study of nonequilibrium thermodynamics in a
classical two-state system, namely a metallic single-electron box. We have
measured with high statistical accuracy the distribution of dissipated energy
as single electrons are transferred between the box electrodes. The obtained
distributions obey Jarzynski and Crooks fluctuation relations. A comprehensive
microscopic theory exists for the system, enabling the experimental
distributions to be reproduced without fitting parameters.
