Hole spin qubits in Si and Ge quantum dots: Ultrafastgates and noise resilient qubits

Hole spin qubits in Si and Ge quantum dots are frontrunner platforms for scalable quantum computers. In these systems, the spin-orbit interactions permit efficient and ultrafast all-electric qubit control, but, at the same time, enhance the susceptibility of the qubit to charge noise. We show that in planar Ge/SiGe heterostructures and in Si fin field-effect transistors (FinFETs), these interactions can be fully tuned by the design of the quantum dot and by external electric fields [1], enabling sweet spots where the charge noise can be completely removed [2]. Remarkably, in Si FInFETs, also the noise caused by hyperfine interactions with nuclear spins -another leading source of decoherence in spin qubits- can be suppressed at these sweet spots [3], greatly enhancing the coherence of these qubits, and reducing the need for expensive isotopically purified materials.