Edge theories in projected entangled pair state models.
We analyze the low energy excitations of spin lattice systems in two dimensions at zero temperature within the framework of projected entangled pair state models. Perturbations in the bulk give rise to physical excitations located at the edge. We identify the corresponding degrees of freedom, give a procedure to derive the edge Hamiltonian, and illustrate that it can exhibit a rich phase diagram. For topological models, the edge Hamiltonian is constrained by the topological order in the bulk, which gives rise to one-dimensional edge models with unconventional properties; for instance, a topologically ordered bulk can protect a ferromagnetic Ising chain at the edge against spontaneous symmetry breaking.
Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching, Germany.
S
S
Yang
Institut für Quanteninformation, RWTH Aachen University, D-52056 Aachen, Germany.
L
L
Lehman
Laboratoire de Physique Théorique, C.N.R.S. and Université de Toulouse, F-31062 Toulouse, France.
D
D
Poilblanc
Department of Physics and Astronomy, Ghent University, Krijgslaan 281, S9, 9000 Gent, Belgium.
K
K
Van Acoleyen
Department of Physics and Astronomy, Ghent University, Krijgslaan 281, S9, 9000 Gent, Belgium and Vienna Center for Quantum Science and Technology, Universität Wien, Boltzmanngasse 5, A-1090 Wien, Austria.
F
F
Verstraete
Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching, Germany.
J I
JI
Cirac
Institut für Quanteninformation, RWTH Aachen University, D-52056 Aachen, Germany.
N
N
Schuch