Tabuchi Yutaka, Ishino Seiichiro, Ishikawa Toyofumi, Yamazaki Rekishu, Usami Koji, Nakamura Yasunobu
Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan.
Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan and Center for Emergent Matter Science (CEMS), RIKEN, Wako, Saitama 351-0198, Japan.
Phys Rev Lett. 2014 Aug 22;113(8):083603. doi: 10.1103/PhysRevLett.113.083603.
We demonstrate large normal-mode splitting between a magnetostatic mode (the Kittel mode) in a ferromagnetic sphere of yttrium iron garnet and a microwave cavity mode. Strong coupling is achieved in the quantum regime where the average number of thermally or externally excited magnons and photons is less than one. We also confirm that the coupling strength is proportional to the square root of the number of spins. A nonmonotonic temperature dependence of the Kittel-mode linewidth is observed below 1 K and is attributed to the dissipation due to the coupling with a bath of two-level systems.
我们展示了钇铁石榴石铁磁球体中的静磁模式（基特尔模式）与微波腔模式之间的大正常模式分裂。在热激发或外部激发的磁振子和光子的平均数量小于1的量子区域中实现了强耦合。我们还证实，耦合强度与自旋数的平方根成正比。在1K以下观察到基特尔模式线宽的非单调温度依赖性，这归因于与两能级系统库耦合导致的耗散。
