  Jarzynski's equality is a well-known result in statistical mechanics,
relating free-energy differences between equilibrium ensembles with
fluctuations in the work performed during non-equilibrium transformations from
one ensemble to the other. In this work, an extension of this relation to
lattice gauge theory will be presented, along with numerical results for the
$\mathbb{Z}_2$ gauge model in three dimensions and for the equation of state in
$\mathrm{SU}(2)$ Yang-Mills theory in four dimensions. Then, further
applications will be discussed, in particular for the Schr\"odinger functional
and for the study of QCD in strong magnetic fields.
