  New exact results about the nonequilibrium thermodynamics of open quantum
systems at arbitrary timescales are obtained by considering all possible
variations of initial conditions of a system, its environment, and correlations
between them. First we obtain a new quantum-information theoretic equality for
entropy production, valid for an arbitrary initial joint state of system and
environment. For any finite-time process with a fixed initial environment, we
then show that the contraction of the system's distinction -- relative to the
minimally dissipative state -- exactly quantifies its thermodynamic
dissipation. The quantum component of this dissipation is the change in
coherence relative to the minimally dissipative state. Implications for quantum
state preparation and local control are explored. For nonunitary processes --
like the preparation of any particular quantum state -- we find that mismatched
expectations lead to divergent dissipation as the actual initial state becomes
orthogonal to the anticipated one.
