## Upcoming Seminars

Date/Place | Dec. 05th (Tues.) 15:30-16:30 / H711 |
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Name | Keun-Young Kim(GIST) |

Title | Renormalized holographic complexity |

Abstract | Recently, quantum informational concepts such as entanglement entropy and complexity are playing important roles in quantum field theory and gravity. Roughly speaking, the complexity of a state is the minimum number of simple gates required to produce this state from a reference state. From the holographic perspective, there are two proposals to compute the complexity: CV(complexity =volume) conjecture and CA(complexity = action) conjecture. I will briefly review both conjectures. However, it turns out that both are UV divergent. To define a finite complexity, we propose a "renormalized complexity" by employing a similar method to the holographic renormalization. |

Date/Place | Dec. 12th (Tues.) 15:30-16:30 / H711 |
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Name | Naoto Yokoi (Tohoku University, Institute for Materials Research) |

Title | Stimulated Emission of Dark Matter Axion in Condensed Matter |

Abstract | Abstract: We discuss the stimulated emission process of dark matter axions from collective excitations in various condensed matter systems. If axions constitute a condensate in the halo of our galaxy, the stimulated emissions of the axions from a type of condensed matter excitations can be detectable. As a concrete example, an emission of dark matter axions from magnetic vortex strings in a type II superconductor is investigated along with possible experimental signatures. |

Date/Place | Dec. 19th (Tues.) 15:30-16:30 / H711 |
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Name | Shuichi Yokoyama (YITP, Kyoto University) |

Title | Flow equation, conformal symmetry, AdS geometries with general conformally flat boundary |

Abstract | Abstract: In this talk I will speak about my recent works with Sinya Aoki on the study of mechanism of emergence of AdS geometry from CFT via flow equation. A flow equation is a kind of operator renormalization which resolves UV singularity. While this was used to help numerical simulation in lattice QCD, there has recently been a proposal to construct a one higher dimensional geometry associated with the flow equation in a QFT. In our recent papers, I investigated aspects of an induced metric with the collaborator and our main results are the following. i) Generally an induced metric becomes a quantum information metric called the Bures or Helstrom metric. ii) For any CFT, induced metrics explicitly computed match (Poincare) AdS. iii) Conformal symmetry of CFT converts to the AdS isometry after quantum averaging. This guarantees the emergence of AdS without explicit calculation. iv) We generalize ii) and iii) in the case of any CFT defined on a general conformally flat manifold. |