Klaus Ensslin – Bilayer graphene: rich in physics and good for devices
Prof. Klaus Ensslin
Professor of Physics at ETH Zürich, President of the Swiss Quantum Commission
Abstract
Electrons have a charge and a spin degree of freedom. The primitive unit cell in graphene honeycomb lattice has 2 atoms. As a consequence, there is an additional valley degree of freedom in graphene that can be tuned by gate voltages. For electrostatically-defined quantum dots in bilayer graphene this leads to a particular filling sequence, with the first 4 electrons in the s-shell and the next 8 electrons in the p-shell. The details of the level spectrum reveals many surprises, such as a singly-degenerate spin-triplet/valley-singlet states for the two carrier state. When building a qubit, one can utilize all available degrees of freedom: charge, spin and valley. For the so-called Kramers qubits, where spin and valley need to be flipped for relaxation from the excited to the ground state, lifetimes as long as 100 s have been experimentally observed. For graphene layer twisted at the magic angle one can fabricate superconducting devices such as Josephson junctions, SQUIDs and Cooper pairs boxes. In this talk I will present the prospects that graphene offers to investigate physics questions related to topology, superconductivity, spin-orbit interactions and spin-valley coupling as well as device concepts with unprecedented tuning opportunities.
Biography
| Education | |
| May 83 | Vordiplom (Bachelors), University of Munich, Germany |
| April 86 | Diploma in physics (Masters), Eidgenössische Technische Hochschule, ETH-Zürich, Switzerland |
| January 89 | Ph. D. in physics at Max-Planck Institute for solid state research, Stuttgart, Germany |
| January 1995 | Habilitation and Privatdozent at the Physics Department of the University of Munich, Germany |
| Employment | |
| June 86- Feb. 89 | Ph. D. student at Max-Planck-Institut for solid state research, Stuttgart, Germany |
| March 89 - March 91 | Postdoc at the University of California in Santa Barbara |
| April 91 -Sept. 95 | University Assistant at the Physics Department of the University of Munich, Germany |
| since October 1995 | Professor of Physics at ETH Zurich, Switzerland |
| 2011-2022 | Director of National Center for Competence in Research on “Quantum Science and Technology” |
| Since January 2026 | President of the Swiss Quantum Commission |
Location
Leuchs-Russell Auditorium, A.1.500, Staudtstr. 2
Location details
Zoom
https://eu02web.zoom-x.de/j/61245265377?pwd=xD5pyjvV6B80H2siVXoptd6juhH0Ez.1
Meeting-ID: 612 4526 5377
Kenncode: 431516
