Graduate Program in Spintronics Seminar

Prof. Dr. Dominik Zumbühl
Department of Physics, University of BaselDirector, NCCR SPIN

Lecture Title"Spin-orbit coupling in 2D and0D semiconductors"
Date: Tuesday, November 7, 2023, 4:00 p.m.
Place: Materials Development Education and Research Bldg.
Lecture Room 2 (Room 102)

Contact：Makoto Kohda(makoto［at］material.tohoku.ac.jp)

Spin-orbit coupling in 2D and 0D semiconductors
Dominik Zumbühl, University of Basel and NCCR SPIN
The spin-orbit interaction (SOI) arises from the relativistic physics of semiconductor charges,creating magnetic out of electric fields when performing a Lorentz boost into the rest frame ofa charge. The SOI is at the heart of key phenomena in condensed matter physics andconveniently gives access to magnetic degrees of freedom via electric fields. This makes
possible all-electrical coherent spin manipulation while simultaneously opening the door fordephasing by charge noise. In this presentation, I will present aspects of the 2D physics of thequantum oscillations of resistivity, and then turn to the fully confined 0D structures of holespins qubits in Si and Ge quantum dots.
Shubnikov-de Haas (SdH) oscillations are the fingerprint of the Landau and Zeeman splitting
on the resistivity, serving as paradigmatic experimental probe. So far, no analytical description
could be found for the vast majority of parameter space with Rashba, Dresselhaus and Zeeman
terms all present. We bridge this gap by providing an analytical formulation [Candido et al.,arXiv:2304.14327], and derive a simple condition for beating-free SdH oscillations, notably
different from the persistent spin helix for materials with large g* m* such as InAs or InSb.
Semiconductor spins are leading contenders for highly scalable qubits. I will present recent
progress from the NCCR SPIN, the Swiss National Program on Quantum Computation.
Highlights incl. ultrafast qubits, taking only 1 ns to coherently rotate a spin from pointing up
to down; operation of spin qubits up to 5 K, where vast cooling power becomes available,making possible integration of the classical control electronics; operation of a 2-qubit gate withhighly anisotropic exchange, allowing for high fidelity gate operation while operating at highspeeds; and finally a sweet spot combining both qubit coherence and speed, thus opening new
avenues for ultrafast and highly coherent hole spin qubits
This work was supported by the NCCR SPIN, the Swiss NSF, the Swiss Nanoscience Institute(SNI), the Georg H. Endress Foundation, and the EU H2020 European Microkelvin Platform
EMP, FET open TOPSQUAD and QLSI programs.

Bio: Dominik received his PhD at Harvard University in 2004 on quantum coherence andspin in semiconductor quantum dots after receiving a diploma from ETH Zürich in 1998 anda MSc in 2000 from Stanford University. After a 2-year postdoc at MIT, Dominik started hisown group in 2006 at the University of Basel where he has been working since. In 2008, hereceived a starting grant in the first ERC call. He was promoted to associate professor in 2012
and to full professor in 2023. He served as Department Chair from 2015-2019 and since2021, he is the director of the NCCR SPIN, the Swiss National Program on Quantum
Computing with Si and Ge spins. He was elected as a fellow of the American Physical Society(APS) in 2023.
Dominiks research interests are in quantum transport experiments in semiconductor
nanostructures, focusing on quantum computation with spins, coherence, interactions,quantum condensed matter at ultralow temperatures and machine learning for quantum
devices.