On-demand electrical control of spin qubits

Abstract

High-performance all-electrical control is a prerequisite for scalable silicon quantum computing. The switchable interaction between spins and orbital motion of electrons in silicon quantum dots now enables the electrical control of a spin qubit with high fidelity and speed, without the need for integrating a micromagnet. Once called a ‘classically non-describable two-valuedness’ by Pauli, the electron spin forms a qubit that is naturally robust to electric fluctuations. Paradoxically, a common control strategy is the integration of micromagnets to enhance the coupling between spins and electric fields, which, in turn, hampers noise immunity and adds architectural complexity. Here we exploit a switchable interaction between spins and orbital motion of electrons in silicon quantum dots, without a micromagnet. The weak effects of relativistic spin–orbit interaction in silicon are enhanced, leading to a speed up in Rabi frequency by a factor of up to 650 by controlling the energy quantization of electrons in the nanostructure. Fast electrical control is demonstrated in multiple devices and electronic configurations. Using the electrical drive, we achieve a coherence time T _2,Hahn ≈ 50 μs, fast single-qubit gates with T _π/2 = 3 ns and gate fidelities of 99.93%, probed by randomized benchmarking. High-performance all-electrical control improves the prospects for scalable silicon quantum computing.