Optimisation of electron spin qubits in electrically driven multi-donor quantum dots

Abstract

Abstract Multi-donor quantum dots have been at the forefront of recent progress in Si-based quantum computation. Among them, 2 P : 1 P spin qubits have a built-in dipole moment, making them ideal for electron dipole spin resonance (EDSR) using the donor hyperfine interaction, and thus all-electrical spin operation. We report fast EDSR, with T π ~ 10 − 50 ns and a Rabi ratio ( T 1 / T π ) ~ 10 6 . The fastest EDSR time T π occurs when the 2 P : 1 P axis is ∥ [111], while the best Rabi ratio occurs when it is ∥ [100]. Sensitivity to random telegraph noise due to nearby charge defects depends strongly on the location of the nearby defects. The qubit is robust against 1/ f noise provided it is operated away from the charge anti-crossing. Entanglement via exchange is several orders of magnitude faster than dipole-dipole coupling. These findings pave the way towards fast, low-power, coherent and scalable donor dot-based quantum computing.