Landau-Zener interferometry of valley-orbit states in Si/SiGe double quantum dots

Electrons confined in Si quantum dots possess orbital, spin, and valley degrees of freedom (DOF). We perform Landau-Zener-Stückelberg-Majorana (LZSM) interferometry on a Si double quantum dot that is strongly coupled to a microwave cavity to probe the valley DOF. The resulting LZSM interference pattern is asymmetric as a function of level detuning and persists for drive periods that are much longer than typical charge decoherence times. By correlating the LZSM interference pattern with charge-noise measurements, we show that valley-orbit hybridization provides some protection from the deleterious effects of charge noise. Our work opens the possibility of harnessing the valley DOF to engineer charge-noise-insensitive qubits in Si.