Probing the Hierarchy of Genuine Multipartite Entanglement with Generalized Latent Entropy

TL;DR

This paper introduces a generalized Latent Entropy measure to quantify and analyze the hierarchical structure of genuine multipartite entanglement in pure quantum states, with applications to random states and SYK models.

Contribution

It proposes a new generalized L-entropy measure that satisfies axioms for GME, captures entanglement hierarchy, and applies it to complex quantum systems like SYK models.

Findings

Maximal L-entropy saturates upper bounds for odd n in large local-dimension limit.

For even n, L-entropy approaches the bound asymptotically.

L-entropy effectively probes entanglement variations in SYK model variants.

Abstract

We introduce generalization of the recently proposed Latent Entropy (L-entropy) [1] as a refined measure of genuine multipartite entanglement (GME) in pure states of $n$-party quantum systems. Generalized L-entropy satisfies the axioms required for a valid GME measure and provides a natural ordering among $k$-uniform states maximizing for absolutely maximally entangled states (AME), effectively capturing the hierarchical structure of multipartite entanglement. We analyze the behavior of this measure for $n$-party Haar-random states and demonstrate that, in the large local-dimension limit, the maximal L-entropy saturates its upper bound for odd $n$, while for even $n$ it approaches the bound asymptotically. Furthermore, we apply this framework to examine multipartite entanglement properties of quantum states in several variants of the Sachdev--Ye--Kitaev (SYK) model, including SYK$_4$, SYK$_2$, mass-deformed SYK, sparse SYK, and $\mathcal{N}=2$ supersymmetric SYK. The results demonstrate that the generalized L-entropy serves as a sensitive probe of multipartite entanglement, revealing how deformations influence quantum entanglement structure in such strongly interacting systems.