  The continuous Multiscale Entanglement Renormalization Ansatz (cMERA)
[Haegeman et al., Phys. Rev. Lett. 110, 100402 (2013)] gives a variational
wavefunctional for ground states of quantum field theoretic Hamiltonians. A
cMERA is defined as the result of applying to a reference unentangled state a
unitary evolution generated by a quasilocal operator, the entangler. This makes
the extension of the formalism to the case where boundaries and defects are
present nontrivial. Here we show how this generalization works, using the 1+1d
free boson cMERA as a proof-of-principle example, and restricting ourselves to
conformal boundaries and defects. In our prescription, the presence of a
boundary or defect induces a modification of the entangler localized only to
its vicinity, in analogy with the so-called principle of minimal updates for
the lattice tensor network MERA.
