  The so-called entanglement with vacuum is not a property of the Fock space,
but of some rather pathological representations of CCR/CAR algebras. In some
other Fock space representations the notion simply does not exist. We have
checked all the main Gedanken experiments where the notion of entanglement with
vacuum was used, and found that all the calculations could be performed at a
representation-independent level. In particular any such experiment can be
formulated in a Fock-space representation where the notion of entanglement with
vacuum is meaningless. So, for the moment there is no single experiment where
the notion is needed, and probably it is simply unphysical.
