Quantum Control of Artificially Built Spin Structures on Surfaces*

The last few decades have witnessed remarkable revolutions in quantum mechanics and information science, driven by the desire to employ quantum states for carrying and processing information. While various material platforms have been extensively studied for realizing quantum technologies, single atoms and molecules on surfaces have been recently explored to demonstrate quantum information processing and quantum sensing since the successful integration of electron spin resonance techniques with scanning tunneling microscopy (ESR-STM) [1,2].

In this talk, I will focus on recent advancements in quantum-coherent experiments performed using ESR-STM that enables coherent control of spins at the Angstrom length scale. Since the first demonstration of coherent manipulation of single spins on surfaces [3], one of the biggest challenges has been extending this study to multiple spins, as STM studies are typically localized to the spin located at the STM junction. Recently, we have developed a way to control and detect spins that are not positioned at the STM junction. Based on this new approach, we successfully demonstrated the coherent manipulation of multiple electron qubits built using titanium and iron atoms on a surface [4]. This work exhibits the enhanced coherent properties of remote spins as well as rapid controlled operations of multi-electrons in an all-electrical fashion. In addition, I will present our recent efforts to extend this work to the 4f electron systems [5], where we anticipate prolonged spin relaxation and coherence times due to the intrinsic isolation of 4f electrons. Lastly, I will discuss atomic-scale quantum sensing achieved using ESR-STM with a spin sensor attached to the STM tip, which enables the detection of magnetic and electrostatic fields at subnanometer precision. This series of recent advancements represents the versatile applications of ESR-STM in the realm of quantum technologies.

[1] S. Baumann et al., Science 350, 417 (2015).

[2] Y. Chen, Y. Bae, and A. Heinrich. Adv. Mater. 2107534 (2022)

[3] K. Yang et al., Science 366, 509 (2019)

[4] Y. Wang et al., Science 382, 87 (2023)

[5] S. Reale et al., arXiv:2309.02348 (2023)