  We predict a generic manifestation of quantum interference in many-body
bosonic systems resulting in a coherent enhancement of the average return
probability in Fock space. This enhancement is both robust with respect to
variations of external parameters and genuinely quantum insofar as it cannot be
described within mean-field approaches. As a direct manifestation of the
superposition principle in Fock space, it arises when many-body equilibration
due to interactions sets in. Using a semiclassical approach based on
interfering paths in Fock space, we calculate the magnitude of the
backscattering peak and its dependence on gauge fields that break time-reversal
invariance. We confirm our predictions by comparing them to exact quantum
evolution probabilities in Bose-Hubbard models, and discuss the relevance of
our findings in the context of many-body thermalization.
