  It is observed that the shifted Poisson structure (antibracket) on the
solution complex of Klein-Gordon and linear Yang-Mills theory on globally
hyperbolic Lorentzian manifolds admits retarded/advanced trivializations
(analogs of retarded/advanced Green's operators). Quantization of the
associated unshifted Poisson structure determines a unique (up to equivalence)
homotopy algebraic quantum field theory (AQFT), i.e. a functor that assigns
differential graded $\ast$-algebras of observables and fulfills homotopical
analogs of the AQFT axioms. For Klein-Gordon theory the construction is
equivalent to the standard one, while for linear Yang-Mills it is richer and
reproduces the BRST/BV field content (gauge fields, ghosts and antifields).
