Many-body states under measurements: from quantum entanglement to magic

4 Aug 2026, 17:30
1h
Lecture Hall (Kavli IPMU)

Lecture Hall

Kavli IPMU

Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8583, Japan

Speaker

Yuto Ashida

Description

Recent advances in programmable quantum systems have made it possible to monitor and control many-body states at the single-quantum level. In this talk, I shall discuss how quantum measurements open new frontiers at the interface of many-body physics and quantum information. I will first introduce how measurement backaction leads to intriguing many-body phenomena in open systems, such as measurement-induced entanglement transitions and criticality. I will then turn to many-body quantum resources, focusing on quantum magic, as a resource for universal quantum computation. By formulating stabilizer Rényi entropy as a participation entropy in a doubled Hilbert space, I will explain how many-body magic can be viewed as a property of quantum states under Bell measurements. This perspective enables a boundary conformal field theory analysis of universal magic scaling in one-dimensional critical states, including systems with periodic boundaries, open boundaries, and topological defects. I will also highlight how universal subleading terms are governed by boundary entropies, scaling dimensions, and defect fusion rules.

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