News

Marie Sklodowska-Curie Actions: award for physicist Daniel Barragan

  • Faculté des Sciences, des Technologies et de Médecine (FSTM)
    30 mars 2020
  • Catégorie
    Recherche
  • Thème
    Physique & sciences des matériaux

Daniel Barragan-Yani, postdoctoral researcher within the Department of Physics and Materials Science at the University of Luxembourg, has recently been awarded a Marie Curie Individual Fellowship from the European Commission. With a budget of 178.320 euros for two years, Daniel will work on defect-based quantum technology.

The charm of defects

Since January 2019, Dr. Daniel Barragan-Yani has been part of the Theoretical Solid State Physics group, where he continues to deepen his understanding of the physics of defects. When asked why he finds these systems so interesting, Dr. Barragan-Yani explains that defects break the symmetry of a crystal allowing new phenomena and applications. “A phrase often attributed to Sir Charles Frank ‘crystals are like people, it is the defects in them that makes them interesting’ reveals perfectly the origin of my attraction for defects”, says Daniel. He also remarks that before joining Prof. Ludger Wirtz’s research group, he obtained his PhD from the Technische Universität Darmstadt in Germany, where he studied the structural and electronic properties of dislocations, the most important line defects in a crystal near which the regular atomic arrangement is broken. It was during this time when he came to realize that the idea of beneficial defects, usually associated only with for zero-dimensional or point defects, could also be extended to dislocations. Furthermore, he became aware that defect-based quantum technologies, an exciting new area of defect physics, could strongly benefit from his idea.

Schematic of the central idea in Q-Line. To the left, a dislocation (red circle) seen here perpendicular to the page induces a strain field (gray area). To the right, relevant point defects (green circles) interact with the strain field of the dislocation (seen now in the plane of the page and depicted as a red line) and move towards their preferred atomic sites along the dislocation (white circles).

QLINE project

A quantum computer is a device that exploits the quantum behaviour of its constituents (“qubits”) to solve a computational problem. One of the proposed hardware options to build such a device are point defects in solids, which hold promise of scalability and integration with current semiconductor technology. However, it remains challenging to position the point defects in a deterministic array and to integrate them into large networks.

In order to address these two issues, Daniel proposes to use dislocations as a “quantum bus” able to both create a deterministic pattern of relevant point defects, see figure above, and to connect them by means of localized vibrational modes (phonons). This idea is at the center of the QLINE project and represents a technological leap that paves the way for a quantum computer implementation that is fully defect-based, from its construction to its functioning. In order to carry out the project, it is necessary to combine the theoretical study of the stability and geometry of point and line defects with advanced electronic structure calculations of their spectroscopic properties.

“This is the basic strength of our proposal, it brings together the two complementary research profiles needed to carry the project. On the one hand, I’m an expert on the physics of dislocations and their interactions with point defects and, on the other hand, Prof Wirtz is an expert on many-body perturbation theory”, says Daniel.

The strength of this collaboration convinced the European commission to grant the Marie Skłodowska-Curie Actions –Individual Fellowship (MSCA-IF) for the project QLINE, set to start in April 2021, which opens a completely new area of research and will help in putting Luxembourg at the forefront of the development of quantum technologies.