Ultrafast and Electrically Tunable Rabi Frequency in a Germanium Hut Wire Hole Spin Qubit

Abstract

Hole spin qubits based on germanium (Ge) have strong tunable spin-orbit interaction (SOI) and ultrafast qubit operation speed. Here we report that the Rabi frequency (<i>f</i>_Rabi) of a hole spin qubit in a Ge hut wire (HW) double quantum dot (DQD) is electrically tuned through the detuning energy (ϵ) and middle gate voltage (<i>V</i>_M). <i>f</i>_Rabi gradually decreases with increasing ϵ; on the contrary, <i>f</i>_Rabi is positively correlated with <i>V</i>_M. We attribute our results to the change of electric field on SOI and the contribution of the excited state in quantum dots to <i>f</i>_Rabi. We further demonstrate an ultrafast <i>f</i>_Rabi exceeding 1.2 GHz, which indicates the strong SOI in our device. The discovery of an ultrafast and electrically tunable <i>f</i>_Rabi in a hole spin qubit has potential applications in semiconductor quantum computing.