Prof Arzhang Ardavan

Abstract:

Inside Front Cover
In article number 2300095, Hesjedal and co-workers demonstrate that the substitution of Co2+ ions into the halide perovskite imparts magnetic behavior to the material while maintaining photovoltaic performance. We utilize the Co2+ ions (shown as robots) themselves as probes to sense the local electronic environment of lead in the perovskite, thereby opening the substitution gateway for developing novel functional perovskite materials and devices for future technologies.

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