  The Free Energy Principle (FEP) states that under suitable conditions of weak
coupling, random dynamical systems with sufficient degrees of freedom will
behave so as to minimize an upper bound, formalized as a variational free
energy, on surprisal (a.k.a., self-information). This upper bound can be read
as a Bayesian prediction error. Equivalently, its negative is a lower bound on
Bayesian model evidence (a.k.a., marginal likelihood). In short, certain random
dynamical systems evince a kind of self-evidencing. Here, we reformulate the
FEP in the formal setting of spacetime-background free, scale-free quantum
information theory. We show how generic quantum systems can be regarded as
observers, which with the standard freedom of choice assumption become agents
capable of assigning semantics to observational outcomes. We show how such
agents minimize Bayesian prediction error in environments characterized by
uncertainty, insufficient learning, and quantum contextuality. We show that in
its quantum-theoretic formulation, the FEP is asymptotically equivalent to the
Principle of Unitarity. Based on these results, we suggest that biological
systems employ quantum coherence as a computational resource and - implicitly -
as a communication resource. We summarize a number of problems for future
research, particularly involving the resources required for classical
communication and for detecting and responding to quantum context switches.
