The valley degree of freedom presents challenges and opportunities for silicon spin qubits. An important consideration for singlet-triplet states is the presence of two distinct triplets, composed of valley vs orbital excitations. Here, we show that both of these triplets are present in the typical operating regime, but that only the valley-excited triplet offers intrinsic protection against charge noise. We further show that this protection arises naturally in dots with stronger confinement. These results reveal an inherent advantage for silicon-based multielectron qubits.

中文翻译：

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Si/SiGe异质结构中双电子量子点的电荷噪声弹性

谷自由度为硅自旋量子比特带来了挑战和机遇。单重三重态的一个重要考虑因素是存在两个不同的三重态，由谷与轨道激发组成。在这里，我们展示了这两个三重态都存在于典型的工作状态中，但只有谷激发三重态才能提供对电荷噪声的内在保护。我们进一步表明，这种保护自然地出现在具有更强限制的点中。这些结果揭示了硅基多电子量子比特的固有优势。