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

TL;DR

This paper proposes a bichromatic control scheme for Ge hole spin qubits that cancels second order frequency shifts, reduces charge noise sensitivity, and improves gate fidelity without complex engineering.

Contribution

It introduces a novel bichromatic driving method that cancels second order frequency shifts and enhances qubit stability without additional hardware modifications.

Findings

Bichromatic control cancels second order frequency shifts.

The method creates a wider operating window for qubits.

It improves single qubit gate fidelity by reducing charge noise sensitivity.

Abstract

Germanium quantum dot hole spin qubits are compatible with fully electrical control and are progressing toward multi-qubit operations. However, their coherence is limited by charge noise and driving field induced frequency shifts, and the resulting ensemble $1/f$ dephasing. 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 (EDSR) 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 reduces sensitivity to quasi-static charge noise and thus enhances single qubit gate fidelity. 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.