February 2021
Abstracts of the QSIT/Quantum Center, ETH Zurich Lunch Seminar, Thursday, February 4, 2021
Escape dynamics of active particles in multistable potentials
Andrei Militaru - Photnics Laboratory (Novotny group), ETH Zurich
Brownian particles transitioning across potential barriers represent an idealized description of a great variety of complex phenomena, notable ones being chemical reactions and protein folding. The mathematical framework pioneered by Kramers marks an outstanding milestone that enables us to accurately predict the transition rates of systems subject to conservative forces [1]. In this talk, we will go one step beyond Kramers’ theory and study the transition rates of a levitated active particle, i.e. a self-propelled particle whose orientation follows brownian precession [2]. Active particles are an example of nonconservative, nongaussian and nonmarkovian evolution, leading to intriguing functional dependencies of their transition rates.
[1] L. Rondin et al., Nat. Nanotech., 12, 1130-1133 (2017)
[2] A. Militaru, M. Innerbichler et at., arXiv:2012.04478 (2020) (under review)
Modulation Doping of Template-Defined InGaAs Nanowires
Kristopher Cerveny - Quantum Coherence Lab (Zumbühl group), University of Basel
Templated semiconductor nanowires with strong spin-orbit interaction (SOI) are a scalable and versatile platform [1] to create and study novel quantum states of matter. Modulation doping is a very well established technique to enhance mobility and control carrier concentration. Here, we report recent results on InGaAs nanowires with remote doping in the GaAs nanomembrane template grown via molecular beam epitaxy in a selective area growth approach [2]. By confining dopants near the top of the GaAs membrane and increasing the indium content, the process gives major improvements in mean free path and SOI. With a wrap-around top gate, the density was tuned down to full depletion.
[1] M. Friedl, K. Cerveny et al., Nano Lett. 18, 2666-2671 (2018)
[2] M. Friedl, K. Cerveny et al., Nano Lett. 20, 3577-3584 (2020)