paper

Entanglement spectra of non-chiral topological (2+1)-dimensional phases with strong time-reversal breaking, Li-Haldane state counting, and PEPS

arXiv:2207.03246 · doi:10.1103/PhysRevB.108.245150

Abstract

The Li-Haldane correspondence [PRL 101, 010504 (2008)] is often used to help identify wave functions of (2+1)-D chiral topological phases (i.e., with non-zero chiral central charge) by studying low-lying entanglement spectra (ES) on long cylinders of finite circumference. Here we consider such ES of states [in fact, certain Projected Entangled Pair States (PEPS)] that are not chiral (i.e., having zero chiral central charge), but which strongly break time-reversal as well as reflection symmetry, while preserving their product, the same symmetry as a chiral state. This leads to ES with branches of both right- and left-moving chiralities, but with vastly different velocities. For circumferences much smaller than the inverse entanglement gap scale, the low-lying ES appear chiral in some topological sectors, and precisely follow the Li-Haldane state counting of a truly chiral phase. This could lead one to misidentify the phase as chiral. However, considering the ES in all sectors, one can observe distinct differences from a chiral phase. We explore this in an spin liquid PEPS studied by Kurečić, et al. [PRB 99, 045116 (2019)], where the topologically trivial sector has the state counting of a chiral -level-one [] Conformal Field Theory (CFT). In fact, the PEPS has topological order, with 9 sectors. We compute the ES in minimally entangled states corresponding to these sectors, which map to the 9 anyon types of doubled Chern-Simons Topological Field Theory. The state countings of the ES coincide with our expectation: the ES contain irreps of global symmetry from the tensor products of the (lowest-lying) irrep of primary states of a "high-velocity" chiral CFT with the full content of a "low-velocity" chiral CFT sector, a non-chiral structure beyond that observable in the topologically trivial sector of the ES.

47 pages, 9 figures, 5 tables. As published

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