Work

L Entropy: A New Genuine Multipartite Entanglement Measure

Year: 2026

Type: article

Abstract: We advance "latent entropy" (L entropy) as a novel measure to characterize genuine multipartite entanglement in pure states, applicable to quantum systems with both finite and infinite degrees of freedom. This measure, derived from an upper bound on reflected entropy, attains its maximum for three-party Greenberger-Horne-Zeilinger states and n=4, 5-party 2-uniform states. We establish that it satisfies all essential properties of a genuine multipartite entanglement measure, including being a pure-state entanglement monotone. We further obtain an analog of the Page curve by analyzing the behavior of L entropy in multiboundary wormholes, emphasizing their connection to multipartite entanglement in random states. Specifically, for n=5, we show that random states approximate 2-uniform states, exhibiting maximal multipartite entanglement. Extending these ideas to finite temperatures, we introduce the multipartite thermal pure quantum state, a generalization of the thermal pure quantum state to multipartite systems, and demonstrate that the entanglement structure in states of the multicopy Sachdev-Ye-Kitaev model exhibits finite-temperature 2-uniform behavior.

Source: Physical Review Letters

DOI: 10.1103/kmpl-mdbx

Authors: Jaydeep Kumar Basak, Vinay Malvimat, Junggi Yoon

Institutions: Gwangju Institute of Science and Technology, Kyung Hee 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: hybrid

Estimated APC paid: $3,750

Funders: National Research Foundation of Korea, Ministry of Science and ICT, South Korea