Universal quantum control of an atomic spin qubit on a surface

Abstract Scanning tunneling microscopy (STM) enables the bottom-up fabrication of tailored spin systems on a surface that are engineered with atomic precision. When combining STM electron resonance (ESR), these single and molecular spins can be controlled quantum-coherently utilized as electron-spin qubits. Here we demonstrate universal quantum control such qubit by employing coherent along two distinct directions, achieved consecutive radio-frequency (RF) pulses well-defined phase difference. We first show transformations each Cartesian component Bloch vector quantization axis, followed ESR-STM detection. Then ability to generate an arbitrary superposition state using two-axis schemes, in which experimental data excellent agreement simulations. Finally, present implementation dynamical decoupling. Our work extends scope STM-based pulsed ESR, highlighting potential this technique for gate operations qubits surface.