Electric dipole-induced spin resonance of holes in Ge/Si nanowires

Electric dipole-induced spin resonance (EDSR) forms a basic tool in quantum information processing with spin qubits. It enables electrically driven quantum gates and forms a way to accurately probe the energy spectrum of spin qubits. We demonstrate EDSR of hole spins confined in a double quantum dot in a Ge/Si nanowire. The spin-orbit interaction of hole spins in this system has a unique character, as it is predicted to be very strong, potentially enabling GHz Rabi oscillation frequencies, as well as electrically tunable. Recent experiments support this with a demonstration of a 30 nm spin-orbit length and Rabi frequencies exceeding 400 MHz.

Here we perform hole spin spectroscopy through the measurement of EDSR transitions between double dot spin states under various resonance conditions. In particular, we characterize the hole g-tensor as well as the direction of the effective spin-orbit magnetic field through an investigation of EDSR transitions as a function of the magnitude and orientation of an applied external magnetic field . Knowledge of these parameters allows tuning the system towards optimized Rabi oscillation frequencies and minimized decoherence.