Dispersively Probed Microwave Spectroscopy of a Silicon Hole Double Quantum Dot

Hole spin qubits are appealing for quantum information processing, because they can be coherently manipulated with radio-frequency electric fields. The underlying physical mechanism relies on spin-orbit coupling (SOC) in the semiconductor's valence band, and operating a hole spin qubit requires accurate knowledge of SOC parameters that can vary from one qubit to another. To this end, the authors employ a two-tone spectroscopy technique that exploits the same tools used for qubit control and readout: microwave gate-voltage excitation and dispersive gate reflectometry. Their approach will facilitate accurate quantum control of hole spin qubits in scaled semiconductor structures.