Genuine Tripartite Strong Coupling in a Superconducting-Spin Hybrid Quantum System
Authors
Yingqiu Mao
Han-Yu Ren
Zi-Yi Liu
Yi-Zheng Zhen
Tao Rong
Tao Jiang
Zhuo Chen
Zhe-Heng Yuan
Wen-Hua Qin
Xiaoran Zhang
Xiaobing Liu
Ming Gong
Kae Nemoto
William J. Munro
Johannes Majer
Abstract
We demonstrate genuine tripartite strong coupling in a solid-state hybrid quantum system comprising a superconducting transmon qubit, a fixed-frequency coplanar-waveguide resonator, and an ensemble of NV$^-$ centers in diamond. Frequency-domain spectroscopy reveals a characteristic three-mode avoided crossing, indicating that single excitations are coherently shared across all three subsystems. At higher probe powers, we observe nonlinear features including multiphoton transitions and signatures of transmon-${}^{14}\mathrm{N}$ nuclear-spin interactions, highlighting the accessibility of higher-excitation manifolds in this architecture. These results establish a new regime of hybrid cavity QED that integrates superconducting and spin degrees of freedom, providing a platform for exploring complex multicomponent dynamics and developing hybrid quantum interfaces.
