Charge-Noise Resilience of Two-Electron Quantum Dots in Si=SiGe Heterostructures

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.

Automated summary

The valley degree of freedom in silicon spin qubits presents both challenges and opportunities. It has been shown that there are two distinct triplets, composed of valley and orbital excitations, in the typical operating regime. However, only the valley-excited triplet offers intrinsic protection against charge noise. This protection naturally arises in dots with stronger confinement. These results reveal an inherent advantage for silicon-based multielectron qubits.