2D quantum gravity from quantum entanglement

TL;DR

This paper explores how entanglement in quantum systems, analyzed via a modified replica method, leads to a dynamical description of subsystems that can be linked to 2D quantum gravity, supported by numerical evidence.

Contribution

It introduces a novel approach to studying entanglement that incorporates back-reaction, connecting quantum spin chains to 2D quantum gravity through a new fixed point.

Findings

Numerical experiments on the critical Ising model support the theoretical predictions.

The new fixed point exhibits critical exponents matching those of 2D quantum gravity.

The approach demonstrates a link between entanglement dynamics and gravitational theories.

Abstract

In quantum systems with many degrees of freedom the replica method is a useful tool to study the entanglement of arbitrary spatial regions. We apply it in a way which allows them to back-react. As a consequence, they become dynamical subsystems whose position, form and extension is determined by their interaction with the whole system. We analyze in particular quantum spin chains described at criticality by a conformal field theory (CFT). Its coupling to the Gibbs' ensemble of all possible subsystems is relevant and drives the system into a new fixed point which is argued to be that of the 2D quantum gravity coupled to this system. Numerical experiments on the critical Ising model show that the new critical exponents agree with those predicted by the formula of Knizhnik, Polyakov and Zamolodchikov.