Entanglement entropy of quantum many-body systems from unitary disentangling flows

The Ryu-Takayanagi conjecture [1] establishes a remarkable connection between quantum systems and geometry. Specifically, it relates the entanglement entropy to minimal surfaces within the setting of AdS/CFT correspondence. I show that a unitary disentangling flow in an emergent RG-like direction permits a generalization of these ideas to generic quantum many-body Hamiltonians without requiring conformal invariance [2]. The min-entanglement entropy can be obtained in a systematic expansion around a weak-link limit where the region whose entanglement properties one is interested in is weakly coupled to the rest of the system. This formalism also allows for the calculation of subdominant terms in the entanglement entropy and for studying the crossover to volume law behavior at nonzero temperature.

[1] S. Ryu and T. Takayanagi, Phys. Rev. Lett. 96, 181602 (2006)
[2] S. Kehrein, arXiv:1703.03925