Coupling of hole double quantum dot in planar germanium to a microwave cavity

Yuan Kang, Zong-Hu Li, Zhen-Zhen Kong, Fang-Ge Li, Tian-Yue Hao, Ze-Cheng Wei, Song-Yan Deng, Bao-Chuan Wang, Hai-Ou Li, Gui-Lei Wang, Guang-Can Guo, Gang Cao, Guo-Ping Guo

Published 2023-10-12Version 1

In recent years, notable progress has been made in the study of hole qubits in planar germanium, and circuit quantum electrodynamics (circuit QED) has emerged as a promising approach for achieving long-range coupling and scaling up of qubits. Here, we demonstrate the coupling between holes in a planar germanium double quantum dot (DQD) and photons in a microwave cavity. Specifically, a real-time calibrated virtual gate method is developed to characterize this hybrid system, which in turn allows us to determine the typical parameters sequentially through single-parameter fitting instead of conventional multi-parameter fitting with additional uncertainty, and gives the hole-photon coupling rate of $g_0/2\pi$ = 21.7 MHz. This work is a step toward further research on hole-photon interactions and long-range qubit coupling in planar germanium. The experimental method developed in this work contributes to the more accurate and efficient characterization of hybrid cavity-QED systems.