Talk given by

Dr. Philip Willke
Center for Quantum Nanoscience, Institute for Basic Science, Seoul 03760, Korea
Department of Physics, Ewha Womans University, Seoul 03760, Korea
IBM Almaden Research Center, San Jose, CA 95120, USA

Abstract:

Scanning tunneling microscopy (STM) has proven to be an excellent tool to access and manipulate 
the nanoworld. Nevertheless, up to now it did not allow for coherent manipulation of spin systems 
as it is common in other architectures. In this talk I will introduce how we establish a new 
framework for magnetic sensing and quantum coherent control of single atoms by combining electron spin 
resonance and STM [1]. For instance, this technique can be used to sense the magnetic coupling 
between atomic spin centers on the surface [2] and on the STM tip [3]. It also allows us to detect 
the hyperfine interaction between the electron and nuclear spin of different atomic species [4]. 
I will point out how we can extend this technique to a universal atomic-scale sensor to study 
magnetism in molecules and condensed matter systems and how to improve the coherent properties 
of these atomic spin systems.

In addition, STM can be used to map the electron transport in a sample with ultimate spatial 
resolution [5]. In this way, it can reveal the voltage drop, or change in the electrochemical potential 
at localized defects such as grain boundaries. Here, I will discuss how to enhance this technique to 
access quantum transport phenomena on the atomic scale and probe the influence of single adatoms 
and defect centers.

[1] Baumann et al., Science 350, 6259 (2015) 
[2] Choi, …, PW et al., Nature Nanotechnology 12, 420-424 (2017)
[3] Willke, et al., arXiv:1807.08944 (2018)
[4] Willke et al., Science 362, 336–339 (2018). [5] Willke*, Druga* et al., 
Nat. Commun. 6:6399 (2015)