Double resonance of two-coupled s = 1/2 electron spins on a surface using STM*

Atomic-scale control of multiple spins with individual addressability enables the bottom-up design of functional quantum devices. Tailored nanostructures can be built with atomic precision using scanning tunneling microscopes [1]. However, quantum-coherent driving was limited to a spin in the tunnel junction [2]. Here we show the ability to drive and detect the spin resonance of a remote spin using the electric field from the tip and a single-atom magnet placed nearby. The remote spin was weakly coupled to a second spin that was read out by the tunnel current and acted as a quantum sensor. We simultaneously and independently drove the sensor and remote spins by two radio frequency voltages in double resonance experiments, showing promise for multi-spin manipulation in customized spin structures on surfaces. [1] K. Yang et al. Nat. Commun. (2021); [2] K. Yang et al. Science (2019)