Volume-law entanglement fragmentation of quasiparticles

TL;DR

This paper reveals a universal volume-law entanglement fragmentation in quantum states with repeated momentum-space excitations, applicable to free and interacting models, and verified numerically in fermionic and bosonic chains.

Contribution

It introduces a universal decomposition of entanglement entropy into pattern-specific components, applicable across free and interacting quantum systems.

Findings

Universal volume-law entanglement fragmentation observed

Analytical expressions for many-body entanglement derived

Numerical verification in fermionic and bosonic chains

Abstract

We investigate the entanglement entropy in quantum states featuring repeated sequential excitations of unit patterns in momentum space. In the scaling limit, each unit pattern contributes independently and universally to the entanglement entropy, leading to a characteristic volume-law scaling. Crucially, this universal contribution remains identical for both free and interacting models, enabling decomposition of the total entanglement into pattern-specific components. Numerical verification in fermionic and bosonic chains confirms this volume-law fragmentation phenomenon. For fermionic systems, we derive analytical expressions where many-body entanglement becomes expressible through few-body entanglement components. Notably, this analytical framework extends to spin-1/2 XXZ chains through appropriate identifications.