Typical entanglement entropy with charge conservation

arXiv:2604.26141 · quant-ph, cond-mat.stat-mech, gr-qc · Submitted 2026-04-28 · Read on arXiv

quant-ph, cond-mat.stat-mech, gr-qc

Submitted: 2026-04-28

Updated: 2026-09-23

Comments: 36 pages, 9 figures; v2: matches published version

License: http://creativecommons.org/licenses/by/4.0/

The gist: We consider a many-body Hilbert space with a fixed global charge and show that the typical entanglement entropy of a subsystem, at the leading and subleading order in the thermodynamic limit, can be

Terminology

Abstract

We consider a many-body Hilbert space with a fixed global charge and show that the typical entanglement entropy of a subsystem, at the leading and subleading order in the thermodynamic limit, can be expressed in terms of a single quantity which represents the local thermal entropy at fixed charge density. We find a general formula which applies both to abelian U(1) symmetry and non-abelian SU(2) symmetry, including the case of a local Hilbert space which transforms under a general reducible representation of the symmetry group. We illustrate the general formula with model systems and discuss the relevance of the results as a probe of quantum chaos for physical Hamiltonians.

Sources

Related papers