  We show that every finite-dimensional quantum system with Markovian (i.e.,
GKLS-generated) time evolution has an autonomous unitary dilation which can be
dynamically decoupled. Since there is also always an autonomous unitary
dilation which cannot be dynamically decoupled, this highlights the role of
dilations in the control of quantum noise. We construct our dilation via a
time-dependent version of Stinespring in combination with Howland's clock
Hamiltonian and certain point-localised states, which may be regarded as a
C*-algebraic analogue of improper bra-ket position eigenstates and which are
hence of independent mathematical and physical interest.
