Who: Deung-Jang Choi, DIPC
Place: Donostia International Physics Center
Date: Thursday, 26 May 2022, 12:00
DIPC Community Seminars
I will talk about our studies of the properties of magnetic adsorbates as quantum sensors and as building blocks for quantum information. For my talk, I have chosen three topics to show our research activities:
1. Molecules as building blocks for quantum information. Building arrays of spins is of great interest because of their inherent quantum properties. Manipulation and transportation of information have been suggested for these low-dimensional systems . Molecules have unique properties that make them very interesting for creating low- dimensional systems. In our studies, we have focused on molecules which have an enormous conductance change. The bias where the conductance change takes place is determined by the magnetic anisotropy of the molecule. By following the variations of bias, we can obtained pertinent information on how the molecules arrange on the surface. We have shown that using a superconducting STM tip, we can have unprecedented insight in the molecular array .
2. Electron spin resonance (ESR) with the STM. We have been working in unravelling the physics under atomic anisotropic gyromagnetic factors . This is of fundamental interest for understanding entanglement between adsorbed atoms and the possibility of producing quantum operations.
3. Topological quantum computation (TQC) with the STM. TQC can be studied using dynamical manipulation of Majoranas with an STM . This is certainly a very controversial topic despite the large investments made by the information giants (Microsoft, Google, etc). A candidate for Majoranas is the edge state produced at the border of spin chains on an s-wave superconductor. In this context, we have achieved recent evidence that Majoranas may indeed be found .
These three topics are examples of the quantum properties of adsorbates and how they can be revealed and acted upon. Indeed, in the group of quantum phenomena on surfaces (https://www.quantumsurface.tk), we are devoted to showing the extraordinary advantages of the STM as a unique tool that can explore and give access to quantum technologies.
 Colloquium: Atomic spin chains on surfaces. Review of Modern Physics 91, 041001 (2019).
 Superconducting scanning tunneling microscope tip to reveal sub-millielectronvolt magnetic energy variations on surfaces. J. Phys. Chem. Letters 12, 2983 (2021).
 Spin resonance amplitude and frequency of a single atom on a surface in a vector magnetic field. Phys. Rev. B 104, 174408 (2021).
 Atomic manipulation of in-gap states in the Bi2Pd superconductor. Phys. Rev. B 104, 045406 (2021).