Abstract:
The structure of entanglement underpins much of our understanding of modern condensed matter physics. The most basic quantifier, the entanglement entropy, displays universal properties that offer a unique characterization of quantum many-body systems. In this talk I will introduce a technique for computing entanglement entropy in quantum Monte Carlo simulations, based on the concept of nonequilibrium work to compute free energy differences, which allows for precise calculations of unprecedented size. As an application of this approach, I will present results on a 2D quantum spin model for deconfined criticality, where emergent symmetry is observed at the critical point between two disparate ordered phases. Finally, I will show how this methodology can be successfully adapted to study 2D models of interacting fermions. This is applied to the Hubbard model on the honeycomb lattice, which realizes a Dirac semi-metal phase separated by a Gross-Neveu transition from an antiferromagnetic Mott insulator. I will present results throughout the phase diagram and at the critical point of this model, where universal logarithmic terms of the entanglement entropy are observed for the first time.