Atomic-Scale Quantum Coherent Science with Spins on Surfaces
The desire to probe and control individual quantum systems has driven significant scientific and engineering advances in quantum coherent nanoscience. Single atoms and molecules on surfaces, on the other hand, have been extensively studied in search of novel electronic and magnetic functionalities. These two paths came together in 2015 when it was clearly demonstrated that individual spins on surfaces can be coherently controlled and read out in an all-electrical fashion [1]. The enabling technique is scanning tunneling microscopy (STM) combined with electron spin resonance (ESR) [2], which provides unprecedented coherent controllability at the Angstrom length scale.
In this talk, a new approach to coherently control multiple electron spins in artificially built spin structures on surfaces will be presented [3]. We found remote spins, which are outside the tunnel junction, can be controlled by the local oscillating magnetic fields created by a single-atom magnet placed next to them in oscillating electric fields. The read-out of multiple spins is achieved by a sensor atom weakly coupled to them. While traditional STM studies have focused on spins located at the STM junction, our new approach paves the way for extending STM's capability to harness multiple spins in coherent manner. Furthermore, we recently succeeded in functionalizing the STM tip with spin-polarized magnetic atoms and an ESR-active spin center, which allows us to use this STM tip as a mobile ESR sensor and facilitate the precise detection of the electric and magnetic fields at the atomic level. Our work widens the approaches for tailoring spin structures on surfaces with atomic precision in the realm of the quantum information science and the quantum sensing.
