Entanglement at an O(3) Critical Point with a Numerical Linked-Cluster Expansion

Using the Numerical Linked-Cluster Expansion technique on rectangular clusters, we study the scaling of Renyi entanglement entropies at an O(3) quantum critical point, realized through the spin-1/2 Heisenberg bi-layer. There is a subleading logarithmic contribution to the entanglement due to the presence of a vertex in the entanglement boundary, with a coefficient that is known to be universal. We compute this ``corner coefficient'' and compare our value to that from both a non-interacting field theory, and the Ising fixed point in 2+1 dimensions. The corner coefficient has the potential to distinguish between these and other universality classes, through a variety of numerical calculations of strongly interacting quantum critical points.