Universal entanglement entropy in the ground state of biased bipartite systems

TL;DR

This paper demonstrates that the entanglement entropy in bipartite quantum systems follows a universal power-law at large occupancy ratios, with different exponents indicating conserved quantities, and shows how occupancy measurements can infer entanglement.

Contribution

It introduces a universal power-law behavior of entanglement entropy in bipartite systems and links conserved quantities to the power-law exponents, enabling entanglement inference from occupancy data.

Findings

Entanglement entropy follows a universal power-law at large R.

Different conserved quantities lead to distinct power-law exponents.

Occupancy measurements can infer bipartite entanglement entropy.

Abstract

The ground state entanglement entropy is studied in a many-body bipartite quantum system with either a single or multiple conserved quantities. It is shown that the entanglement entropy exhibits a universal power-law behaviour at large $R$ -- the occupancy ratio between the two subsystems. Single and multiple conserved quantities lead to different power-law exponents, suggesting the entanglement entropy can serve to detect hidden conserved quantities. Moreover, occupancy measurements allow to infer the bipartite entanglement entropy. All the above results are generalized for the R\'enyi entropy.