Hyejin Ju, Ann B. Kallin, Paul Fendley, Matthew B. Hastings, Roger G. Melko
We numerically determine subleading scaling terms in the ground-state entanglement entropy of several two dimensional (2D) gapless systems, including a Heisenberg model with Neel order, a free Dirac fermion in the \pi-flux phase, and the nearest-neighbor resonating-valence bond wavefunction. For these models, we show that the entanglement entropy between cylindrical regions of length x and L-x, extending around a torus of length L, depends upon the dimensionless ratio x/L. This can be well-approximated on finite-size lattices by a function \ln(sin(\pi x/L)) akin to the familiar chord-length dependence in one dimension. We provide evidence, however, that the precise form of this bulk-dependent contribution is a more general function in the 2D thermodynamic limit.
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http://arxiv.org/abs/1112.4474
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