Poilblanc, Didier and Schuch, Norbert and Pérez-García, David and Cirac, J. Ignacio (2012) Topological and Entanglement Properties of Resonating Valence Bond wavefunctions. Physical Review B, 85 (23). Art. No. 235151. ISSN 1098-0121 http://resolver.caltech.edu/CaltechAUTHORS:20120713-133343155
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We examine in details the connections between topological and entanglement properties of short-range resonating valence bond (RVB) wave functions using projected entangled pair states (PEPS) on kagome and square lattices on (quasi)infinite cylinders with generalized boundary conditions (and perimeters with up to 20 lattice spacings). By making use of disconnected topological sectors in the space of dimer lattice coverings, we explicitly derive (orthogonal) “minimally entangled” PEPS RVB states. For the kagome lattice, using the quantum Heisenberg antiferromagnet as a reference model, we obtain the finite-size scaling with increasing cylinder perimeter of the vanishing energy separations between these states. In particular, we extract two separate (vanishing) energy scales corresponding (i) to insert a vison line between the two ends of the cylinder and (ii) to pull out and freeze a spin at either end. We also investigate the relations between bulk and boundary properties and show that, for a bipartition of the cylinder, the boundary Hamiltonian defined on the edge can be written as a product of a highly nonlocal projector, which fundamentally depends upon boundary conditions, with an emergent (local) SU(2)-invariant one-dimensional (superfluid) t-J Hamiltonian, which arises due to the symmetry properties of the auxiliary spins at the edge. This multiplicative structure, a consequence of the disconnected topological sectors in the space of dimer lattice coverings, is characteristic of the topological nature of the states. For minimally entangled RVB states, it is shown that the entanglement spectrum, which reflects the properties of the (gapless or gapped) edge modes, is a subset of the spectrum of the local Hamiltonian, e.g., half of it for the kagome RVB state, providing a simple argument on the origin of the topological entanglement entropy S_0=−ln2 of the Z_2 spin liquid. We propose to use these features to probe topological phases in microscopic Hamiltonians, and some results are compared to existing density matrix renormalization group data.
|Additional Information:||© 2012 American Physical Society. Received 9 February 2012; published 6 July 2012. D.P. acknowledges support by the "Agence Nationale de la Recherche" under grant No. ANR 2010 BLANC 0406-0. This work was granted access to the HPC resources of CALMIP under the allocation 2012-P1231. D.P. also thanks Steve R. White for sharing DMRG results and Steve A. Kivelson for useful correspondence. N.S. acknowledges helpful discussions with Frank Verstraete and support by the Alexander von Humboldt foundation, the Institute for Quantum Information and Matter (an NSF Physics Frontiers Center with support of the Gordon and Betty Moore Foundation) and the NSF Grant No. PHY-0803371. D.P.-G. acknowledges QUEVADIS and Spanish grants QUITEMAD and MTM2011-26912. J.I.C. acknowledges the EC project Quevadis, the DFG Forschergruppe 635, and Caixa Manresa. This work was initiated at Centro de Ciencias Pedro Pascual (Benasque, Spain).|
|Group:||IQIM, Institute for Quantum Information and Matter|
|Classification Code:||PACS: 75.10.Kt, 03.65.Ud, 03.67.-a, 71.10.-w|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||19 Jul 2012 21:50|
|Last Modified:||26 Dec 2012 15:32|
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