Canceling second-order frequency shifts in Ge hole spin qubits via bichromatic control

Abstract

Germanium quantum dot hole spin qubits are compatible with fully electrical control and are progressing toward multi-qubit operations. However, their coherence and calibration stability are limited by charge noise and drive-induced frequency shifts. Here, we theoretically demonstrate that a bichromatic driving scheme cancels the second-order frequency shift from the control field without sacrificing the electric dipole spin resonance rate, and without additional gate design or microwave engineering. Based on this property, we further demonstrate that bichromatic control creates a wide operating window that compensates static charge-induced resonance offsets during fixed-frequency operation. This method provides a low-power route to a stabler frequency operation in germanium hole spin qubits and is readily transferable to other semiconductor spin qubit platforms.