Building small, fast and hot hole spin qubits in Si and Ge

Quantum computers hold the potential to solve tasks exponentially faster than classical computers.

Hole spins in Ge/Si core/shell nanowires offer exceptionally strong yet electrically tunable spin-orbit interaction (SOI), the direct-Rashba SOI. This allows unprecedented control and facilitates scaling. The Rabi frequency can be tuned with gate voltages, going from fast manipulation to idle modes, demonstrating a “spin-orbit switch”. Spin-flip times as short as ~1 ns are obtained, approaching the strong driving regime, due to a SOI length down to a few nm. This qubit can also operate up to temperatures of 2 K. We are also implementing an exchange based CROT gate and dispersive qubit readout approaching the single shot regime.



The leading transistor for classical scaling is the silicon fin field-effect transistor (FinFET), integrating billions of FinFETs on a chip. Here, we show that a Si FinFET can host a hole spin qubit and operate above 4 K, potentially allowing in-situ integration of the control electronics. We achieve all-electrical control and 1Q gate fidelities at the fault-tolerance threshold. Further, we demonstrate a CROT gate with spin-orbit induced anisotropic exchange interaction, opening the door to high fidelity and fast 2Q gates, thus taking an important step towards quantum information processing.