22-32-201
Fabio Donati – enter for Quantum Nanoscience (QNS), Institute for Basic Science (IBS), Seoul 03760, Republic of Korea
Department of Physics, Ewha Womans University, Seoul 03760, Republic of Korea
Abstract
As the global demand for sustainable technologies rises, reducing the use of lanthanide elements in future devices becomes imperative to mitigate environmental impacts. A viable route toward this goal is the miniaturization of logic units down to the single-atom level. Lanthanide atoms on surfaces have been demonstrated as a promising platform for storing and manipulating classical binary information due to their exceptionally long magnetic lifetimes [Science 352, 318 (2016), Nat. Commun. 12, 4179 (2021)], representing the ultimate limit of downscaling for magnetic storage devices [Appl. Phys. Lett. 119, 160503 (2021)]. The current challenge is to exploit these elements to realize atomic-scale quantum logic units, or qubits.
In this talk, I will discuss the potential of lanthanide atoms on surfaces as a platform for quantum coherent operations. To this end, an atom must possess a suitable ground state that can efficiently couple to microwave fields. By combining X-ray magnetic circular dichroism and density functional theory, we identified erbium (Er) and thulium (Tm) atoms on MgO/Ag(100) as fulfilling these requirements [Phys. Rev. B 107, 045427 (2023)]. Using scanning tunneling microscopy, we demonstrated the all-electrical drive and detection of electron spin resonance, a key prerequisite for achieving quantum coherent control of their spin states [Nat. Commun. 15, 5289 (2024)]. Taking advantage of atomic-precision assembly of a Ti–Er dimer, we tailor the magnetic interaction and fine-tune the mixing between Er and Ti states to achieve coherent control of the Er 4f spin, yielding a tenfold enhancement in spin-driving efficiency compared with isolated Ti atoms. This enhancement originates from an unconventional driving mechanism arising from anisotropic modulation of the magnetic interaction tensor. These results establish a new atomic-scale platform for studying multiphoton transitions and unraveling the microscopic mechanisms enabling coherent spin manipulation in surface-based atomic qubits.
