Stephan Weis


I enjoy working on mathematical problems, mostly in geometry, matrix analysis, and functional analysis. Many of my past projects were inspired by problems of quantum information theory.
I got my PhD in mathematics in 2009 from the University of Erlangen-Nuremberg, Germany, where I wrote my thesis under the supervision of Andreas Knauf and Nihat Ay in the mathematical physics group. My thesis deals with the geometry of non-commutative exponential families (Gibbs states) with several parameters. I completed five post-doctoral research programs:
2010/2011, I worked on convex geometry at University Erlangen-Nuremberg.
2011/2014, I studied the continuity of inference maps with a grant from Arleta Szkoła, in her project on quantum statistics at Max Planck Institute for Mathematics in the Sciences in Leipzig, Germany.
2015/2016 at University of Campinas, São Paulo, Brazil, I began to study the algebraic geometry of joint numerical ranges (linear images of the convex set of density matrices), which led to a paper in the journal SIAGA in 2021.
2016/2018, Jérémie Roland, Atul S. Arora, and I developed quantum algorithms for weak coin flipping at Ecole Polytechnique de Bruxellles, Belgium (results published in a STOC paper in 2019).
2018-07/12, I resumed work on the algebraic geometry of joint numerical ranges at University of Coimbra, Portugal.
Thereafter, I completed a research project on the Choquet theory of energy-constrained density operators, which is motivated by problems of quantum communication. I also completed a project on reduced density matrices.
2020/2023, I taught in secondary schools (Gymnasium) in Berlin, Germany.
In addition to mathematics, I am very much concerned about human-caused environmental damage, and climate change, in particular. As an individual, whenever possible, I strive to minimize my carbon footprint. I've collected a few links (in German) in the section "Weblinks zum Thema Klimawandel" below.

research in mathematics
publications: articles, theses
presentations: slides, videos, posters
web profiles
trivia: Erdős number = 3, Einstein number = 4

Weblinks zum Thema Klimawandel (in German)
BLOG: KlimaLounge von Stefan Rahmstorf, Professor für Physik der Ozeane
Volker Quaschning, Professor für Regenerative Energiesysteme
ins Deutsche übersetzte Blog-Artikel von Skeptical Science
Cranky Uncle, Spiel zur Stärkung der Abwehrkräfte gegen Falschinformationen (auch auf Deutsch und im Browser spielbar)
website last modified on 27 February 2024
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