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Seminars

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  • Title:Signature of quantum chaos in operator entanglement in 2d CFTs
  • Start Date/Time:2019-12-20 / 10:00
  • End Date/Time :2019-12-20 / 11:00
    • Speaker:Prof. Shinsei Ryu (University of Chicago)
    • Place:Lecture Room A of NCTS, 4F, 3rd General Building, Nat'l Tsing Hua Univ.
    • Host:Prof. Po-Yao Chang (NTHU)
    • Abstract:We study operator entanglement measures of the unitary evolution operators of (1+1)-dimensional conformal field theories (CFTs), aiming to uncover their scrambling and chaotic behaviors. In particular, we compute the bi-partite and tri-partite mutual information for various configurations of input and output subsystems, and as a function of time. We contrast three different CFTs: the free fermion theory, compactified free boson theory at various radii, and CFTs with holographic dual. We found that the bi-partite mutual information exhibits distinct behaviors for these different CFTs, reflecting the different information scrambling capabilities of these unitary operators; while a quasi-particle picture can describe well the case the free fermion and free boson CFTs, it completely fails for the case of holographic CFTs. Similarly, the tri-partite mutual information also distinguishes the unitary evolution operators of different CFTs. In particular, its late-time behaviors, when the output subsystems are semi-infinite, are quite distinct for these theories. We speculate that for holographic theories the late-time saturation value of the tri-partite mutual information takes the largest possible negative value and saturates the lower bound among quantum field theories.
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