  In this note, we present a simple derivation, from time-reversal symmetry, of
fluctuation relations for steady-state large deviation functions in
non-equilibrium quantum systems. We further show that a condition of pure
transmission implies extended fluctuation relations, connecting large deviation
functions to mean currents at shifted temperatures and chemical potentials. We
illustrate these concepts in various examples, including the interacting
resonant level model and conformal or integrable models.
