Spin qubits defined by valence band hole states are attractive for quantum information processing due to their inherent coupling to electric fields, enabling fast and scalable qubit control. Heavy holes in germanium are particularly promising, with recent demonstrations of fast and high-fidelity qubit operations. However, the mechanisms and anisotropies that underlie qubit driving and decoherence remain mostly unclear. Here we report the highly anisotropic heavy-hole g-tensor and its dependence on electric fields, revealing how qubit driving and decoherence originate from electric modulations of the g-tensor. Furthermore, we confirm the predicted Ising-type hyperfine interaction and show that qubit coherence is ultimately limited by 1/f charge noise, where f is the frequency. Finally, operating the qubit at low magnetic field, we measure a dephasing time of \({T}_{2}^{* }\) = 17.6 μs, maintaining single-qubit gate fidelities well above 99% even at elevated temperatures of T > 1 K. This understanding of qubit driving and decoherence mechanisms is key towards realizing scalable and highly coherent hole qubit arrays.

由价带空穴态定义的自旋量子位由于其与电场的固有耦合而对量子信息处理很有吸引力，从而实现快速且可扩展的量子位控制。锗中的重空穴特别有前途，最近展示了快速和高保真量子位操作。然而，量子位驱动和退相干背后的机制和各向异性仍不清楚。在这里，我们报告了高度各向异性重孔g张量及其对电场的依赖性，揭示了量子位驱动和退相干如何源自g张量的电调制。此外，我们证实了预测的伊辛型超精细相互作用，并表明量子位相干性最终受到 1/ f电荷噪声的限制，其中f是频率。最后，在低磁场下操作量子位，我们测量出相移时间\({T}_{2}^{* }\)  = 17.6 μs，即使在高温下，单量子位门保真度仍远高于 99% T  > 1 K。对量子位驱动和退相干机制的理解是实现可扩展和高度相干的空穴量子位阵列的关键。