paper

Rényi entanglement entropies in quantum dimer models : from criticality to topological order

arXiv:1108.1699 · doi:10.1088/1742-5468/2012/02/P02003

Abstract

Thanks to Pfaffian techniques, we study the Rényi entanglement entropies and the entanglement spectrum of large subsystems for two-dimensional Rokhsar-Kivelson wave functions constructed from a dimer model on the triangular lattice. By including a fugacity on some suitable bonds, one interpolates between the triangular lattice (t=1) and the square lattice (t=0). The wave function is known to be a massive topological liquid for whereas it is a gapless critical state at t=0. We mainly consider two geometries for the subsystem: that of a semi-infinite cylinder, and the disk-like setup proposed by Kitaev and Preskill [Phys. Rev. Lett. 96, 110404 (2006)]. In the cylinder case, the entropies contain an extensive term -- proportional to the length of the boundary -- and a universal sub-leading constant . Fitting these cylinder data (up to a perimeter of L=32 sites) provides with a very high numerical accuracy ( at t=1 and at ). In the topological liquid phase we find , independent of the fugacity and the Rényi parameter . At t=0 we recover a previously known result, for and for . In the disk-like geometry -- designed to get rid of the boundary contributions -- we find an entropy in the whole massive phase whatever , in agreement with the result of Flammia {\it et al.} [Phys. Rev. Lett. 103, 261601 (2009)]. Some results for the gapless limit are discussed.

33 pages, 17 figures, minor corrections

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