Year: 2026
Type: preprint
Abstract: Entanglement entropy at one-dimensional criticality typically follows the Calabrese--Cardy scaling. In the non-Hermitian critical free-fermion systems studied here, however, we find an additional interval-independent contribution $S_{\rm res}=\log(ΔL)$, which allows the entropy to remain sensitive to energy gaps below the finite-size scale, $Δ<1/L$. We refer to this term as the residual entropy. To understand its infrared origin, we examine finite-depth non-unitary continuous multiscale entanglement renormalization on a ring. Terminating the critical RG circuit before its singular final layer leaves a two-site infrared state. We calculate the entropy of this state directly from its correlation matrix and recover the same \(\log(ΔL)\) dependence. The emergent de Sitter geometry provides a complementary geometric interpretation: extremal curves associated with different boundary intervals extend to a common infrared endpoint, suggesting how the entanglement retained there can contribute equally to their entropies.
Source: arXiv (Cornell University)
Author: Chou, Kuang-Hung
Institution: National Tsing Hua University
Language: English
Topic: Quantum many-body systems
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7170909953