Seminar: “Quantum dots and quantum rings engineered by atom manipulation” (Lecture)
- Wednesday 5 June 2019Add to my calendar
- from 16:00
Dr. Stefan Fölsch (Paul-Drude-Institut für Festkörperelektronik, Berlin, Germany)
Atom manipulation with the scanning tunneling microscope makes it possible to create ultimately small structures at surfaces. We applied this technique to III-V semiconductor surfaces and found that their electrostatic potential landscape can be designed by the controlled positioning of charged adatoms. This approach enables one to construct quantum dots (often called "artificial atoms") with a perfectly defined level structure, as well as dot assemblies (artificial molecules) whose quantum coupling has no intrinsic variation but can nonetheless be tuned over a wide range. In a recent experiment, we constructed atomic rings which enable phase-coherent electron motion along a closed path. Our measurements reveal the generic level structure of a quantum ring including its single ground state and doubly-degenerate excited states. The states can be modified by deliberate incorporation of point defects. The results discussed in this talk illustrate that atom manipulation in combination with scanning tunneling spectroscopy provides detailed insight into the quantum-physical properties of artificial surface structures at the smallest size scales.