PIRSA:24020095

Weak measurement in conformal field theory and holography - VIRTUAL

Jian, S. (2024). Weak measurement in conformal field theory and holography - VIRTUAL. Perimeter Institute. https://pirsa.org/24020095

Jian, Shaokai. Weak measurement in conformal field theory and holography - VIRTUAL. Perimeter Institute, Feb. 27, 2024, https://pirsa.org/24020095 

          @misc{ pirsa_PIRSA:24020095,
            doi = {10.48660/24020095},
            url = {https://pirsa.org/24020095},
            author = {Jian, Shaokai},
            keywords = {Condensed Matter},
            language = {en},
            title = {Weak measurement in conformal field theory and holography -  VIRTUAL},
            publisher = {Perimeter Institute},
            year = {2024},
            month = {feb},
            note = {PIRSA:24020095 see, \url{https://pirsa.org}}
          }

Shaokai Jian Tulane University

DOI 10.48660/24020095
Collection
Talk Type Scientific Series
Subject

Abstract

Weak measurements can be viewed as a soft projection that interpolates between an identity operator and a projection operator, and can induce an effective central charge distinct from the unmeasured CFT. In the first part, I will discuss the effect of measurement and postselection on the critical ground state of a Luttinger liquid theory. Depending on the Luttinger parameter K, the effect of measurement is irrelevant, marginal, or relevant, respectively. When the measurement is marginal, and we find a critical state whose entanglement entropy exhibits a logarithmic behavior with a continuous effective central charge as a function of measurement strength. Inspired by this result, in the second part, I will discuss a holographic description of the weak measurement. The weak measurement is modeled by an interface brane, separating different geometries dual to the post-measurement state and the unmeasured CFT. In an infinite system, the weak measurement is related to ICFT via a spacetime rotation. We find that the holographic entanglement entropy with twist operators located on the defect is consistent in both calculations for ICFT and weak measurements. In a finite system, the weak measurement can lead to a rich phase diagram, in which the post-measurement geometry can realize a Python’s lunch.

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