250th RQC Seminar

• 講演者

  Prof. Hoi IoChun
  ( City University of Hong Kong )

• 日程

  2025年12月19日(金), 16:00 - 17:00 (4:00p.m.-5:00p.m)

• 開催場所

  ハイブリッド（Zoom,
  Seminar Room 345-347, 3F, Main Research Building, Wako Campus / 研究本館3階 セミナー室 345-347 (C01))

• 講演タイトル

  Waveguide Magnonics

• お問合せ

  norilab_rqc_assist[at]ml.riken.jp

講演概要
In this talk, I will explore recent advancements in waveguide magnonics, highlighting two sets of experiments. First, we investigate the use of photonic crystal waveguides as a novel platform for studying light-matter interactions manifested through emitter-photon bound states. While such physics has been well-explored with quantum dots, cold atoms, and superconducting qubits, its application in magnonic systems is largely uncharted. We present the first experimental demonstration of bound-state magnonics, coupling yttrium iron garnet spheres to a microwave photonic crystal waveguide. At room temperature, we achieve magnon-photon bound states characterized by tunable localization, power-dependent interaction modulation through microwave pumping, and long-range magnon-magnon interactions facilitated by overlapping bound states.
In the second part of the talk, we delve into many-body systems where periodic arrays of yttrium iron garnet spheres confine propagating microwave photons to form an open cavity. We observe strong coupling in two types of magnonic cavities by precisely positioning yttrium iron garnet spheres within a dual-waveguide system. In the magnonic Bragg cavity, spheres are arranged at half-wavelength intervals to act as partially reflecting mirrors, creating an efficient Bragg mirror. We document exchange interactions between a magnon mode in an ancillary sphere and the single-mode Bragg cavity, with tunable coupling strength achieved by varying the number of spheres. In the magnonic anti-Bragg cavity, spheres are positioned at three-quarters of a wavelength, revealing a multi-mode cavity with coherent and dissipative coupling mechanisms. Utilizing the unique mobility of the spheres, we map the coupling strength between the magnon mode and the Bragg and anti-Bragg cavities, maintaining strong coupling over a wide-range scan along the waveguide.