  A quantum fluctuation theorem for a driven quantum subsystem interacting with
its environment is derived based solely on the assumption that its reduced
density matrix obeys a closed evolution equation i.e. a quantum master equation
(QME). Quantum trajectories and their associated entropy, heat and work appear
naturally by transforming the QME to a time dependent Liouville space basis
that diagonalizes the instantaneous reduced density matrix of the subsystem. A
quantum integral fluctuation theorem, a steady state fluctuation theorem and
the Jarzynski relation are derived in a similar way as for classical stochastic
dynamics.
