Multipartite Entanglement in Quantum Many-Body Systems

by Prof. Shinsei Ryu (Department of Physics, Princeton University)

Wednesday 8 Apr 2026, 13:30 → 15:30 Asia/Taipei

L124, Physics Building (NTHU)

Quantum entanglement has long served as a central diagnostic in quantum many-body physics. It has played a key role in identifying quantum criticality, characterizing topological order, and probing quantum chaos. Despite its success, most studies have focused on bipartite entanglement, where the system is divided into two parts. More recently, it has become clear that quantum correlations in many-body systems extend beyond this bipartite framework, and that genuinely multipartite entanglement carries essential physical information. To access these richer structures, I will discuss a family of quantities formulated as multi-entropy measures, including examples such as reflected entropy and the modular commutator. Unlike conventional bipartite measures, these quantities are defined for tripartite partitions of the Hilbert space and are sensitive to correlations shared among three or more subsystems. In the context of topologically ordered states, I will explain how these measures encode additional universal data that are not captured by the standard bipartite topological entanglement entropy.