CSRN提案共同プロジェクトNo.26

作成者： Gerrit Bauer（東北大金研）

研究プロジェクト名： Cavity-optomagnonics with YIG

概要： Several groups in the world recently realized strong coherent coupling ofphotons to the ferrimagnet yttrium iron garnet (YIG) in microwave cavities. Thesestudies provide a bridge between the fields of quantum information and spintronics.
We will study the theory of the coupled dynamics of electromagnetic fields (visible andmicrowaves) and the magnetization in YIG spheres and structured thin films.
コアメンバー： Blanterグループ（TU Delft); 宇佐見グループ（東大）; Yanグループ(电子科技大学); Bauerグループ（東北大）.
期待される研究成果： Our study willlead to better understanding of theelectrodynamics of magnetic insulators
when strongly coupled to photons andphonons. We will assess the conditions
to reach the non-linear regime for highquality magnets, which would open
interesting consequences for quantum
manipulation. The electric readout of
the strongly coupled magnetization
dynamics will be addressed as well.

（図面）

Calculated spin wave resonances of a YIG filmwith thickness d in a planar microwave cavity.

2016年度 報告書 （Web公開用）

作成者： Bauer Gerrit （東北大金研）

研究プロジェクト名： Cavity optomagnonics with YIG
概要： Magnets are potential transducers of quantum information between
superconducting qbits and light. In the search for strong coupling we addressed thetheory of ferrimagnet yttrium iron garnet (YIG) spheres interacting with whispering
gallery modes (WGM) of light.
研究成果（実施状況）： We studied thespectra of light in optical fibers coupledmagnetic spheres. We predict that thechiral magnetic surface (Damon Eshbach)modes cause back‐reflection of light withperfect selectivity between Stokes andanti‐Stokes scattering. WGMs may be
used for an efficient optical cooling of themagnetic order.

（図面）
The input light I couples to the whispering
gallery modes (WGM) in a dielectric magnetic
sphere causes forward (T) and backward (R)inelastic scattering by magnons

主要発表論文等：S. Sharma, Y. M. Blanter, and G. E. W. Bauer, Light scattering bymagnons in whispering gallery mode cavities, arXiv:1706.04106v1.
K. Usami, G.E.W. Bauer, S. Sinova, SPICE International Workshop on Spin Cavitronics,
https://www.spice.uni‐mainz.de/spin‐cavitronics‐2018/.

2017年度 報告書 （Web公開用）

作成者： Bauer Gerrit （東北大金研）

研究プロジェクト名： Cavity‐optomagnonics with YIG
概要：Magnets are potential transducers of quantum information between superconducting
qbits and light. In the search for strong coupling we addressed the theory of ferrimagnet yttrium
iron garnet (YIG) spheres interacting with whispering gallery modes (WGM) of light.

研究成果（実施状況）： We model the cooling of a YIG sphereusing a monochromatic laser source. When the magnon lifetimes
are much larger than the optical ones, we can treat the latter as aMarkovian bath for magnons. The steady‐state magnons arecanonically distributed with a temperature that is controlled bythe light intensity. We predict that with state‐of‐the‐arttechnology such a cooling process can significantly reduce thetemperature of the magnetic order.
主要発表論文等：‐ S. Sharma, Y. M. Blanter, and G. E. W. Bauer, Light scattering by magnons in whispering gallery mode
cavities, Phys. Rev. B 96, 094412 (2017).
‐ S. Sharma, Y. M. Blanter, and G. E. W. Bauer, Optical cooling of magnons, arXiv:1804.02683.
‐ J. A. Haigh, N. J. Lambert, S. Sharma, Y. M. Blanter, G. E. W. Bauer, and A. J. Ramsay, Selection rules forcavity‐enhanced Brillouin light scattering from magnetostatic modes, arXiv:1804.00965.
‐ K. Usami, G.E.W. Bauer, S. Sinova, SPICE International Workshop on Spin Cavitronics,
https://www.spice.uni‐mainz.de/spin‐cavitronics‐2018