Electron spin resonance scanning tunneling microscopy beyond a single spin

Electron spin resonance scanning tunneling microscopy (ESR-STM) is a groundbreaking technique that combines atomic-scale spatial resolution with quantum coherent manipulation capability. Over the past decade, rapid advancements in this field have expanded its scope beyond the initial focus on control of single electron spins. This review summarizes the latest developments in this field that transcend the single-spin paradigm, highlighting three directions: tip-based ESR-STM for quantum sensing, multi-spin ESR-STM for quantum gate operations, and nuclear-spin ESR-STM for high-fidelity qubits. The versatility of ESR-STM lies in its ability to detect and coherently control various spin species while simultaneously providing atomic-scale information. This multifaceted capability, combined with recent paradigm-shifting advances, suggests that ESR-STM's full potential is yet to be realized.