Stephan Weis
Mathematician
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short profile
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I enjoy working on problems related to quantum information theory using mathematical methods, preferably geometry. I am familiar with methods of convex geometry, matrix theory, and topology. More recently, I am employing algebraic geometry and functional analysis. You can find further information in the section "research in mathematics" below.
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I obtained a PhD in mathematics from the University of Erlangen, Germany, in 2009
under the guidance of
Andreas Knauf and Nihat Ay. I had several post-doctoral research positions in Germany, Brazil, Belgium, and Portugal. More recently, I worked in secondary education.
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I am concerned about the human-caused destruction of nature,
especially about climate change.
And I am eager to learn what I can do about it as an individual.
I collected some links (in German) in the section
"Weblinks zum Thema Klimawandel" below.
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research in mathematics
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publications: articles, theses
Preprints
Arora, A. S.,
Roland, J.,
Vlachou, C., and Weis, S.,
Solutions to quantum weak coin flipping,
Cryptology ePrint Archive, paper 2022/1101, 2022.
https://ia.cr/2022/1101
Refereed journal papers
19) Weis, S. and
Gouveia, J.,
The face lattice of the set of reduced density matrices and its coatoms,
Information Geometry 6:1, 293-326 (2023).
arXiv
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Journal link
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Full-text
18) Plaumann, D.,
Sinn, R., and Weis, S.,
Kippenhahn's Theorem for joint numerical ranges and quantum states,
SIAM Journal on Applied Algebra and Geometry 5:1, 86-113 (2021).
arXiv
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Journal link
17) Weis, S. and Shirokov, M. E.,
The face generated by a point, generalized affine constraints, and quantum theory,
Journal of Convex Analysis 28:3, 847-870 (2021).
arXiv
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Journal link
16) Weis, S. and Shirokov, M. E.,
Extreme points of the set of quantum states with bounded energy,
Russian Mathematical Surveys 76:1, 190-192 (2021).
arXiv
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Journal link
15) Weis, S.,
A variational principle for ground spaces,
Reports on Mathematical Physics 82:3, 317-336 (2018).
arXiv
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Journal link
14) Spitkovsky, I. M.
and Weis, S.,
Signatures of quantum phase transitions from the numerical range,
Journal of Mathematical Physics 59:12, 121901 (2018).
arXiv
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Journal link
13) Szymański, K.,
Weis, S.,
and Życzkowski, K.,
Classification of joint numerical ranges of three hermitian matrices of size three,
Linear Algebra and its Applications 545, 148-173 (2018).
arXiv
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Journal link (open access)
12) Weis, S.,
Operator systems and convex sets with many normal cones,
Journal of Convex Analysis 25:1, 41–64 (2018).
arXiv
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Journal link
11) Spitkovsky, I. M.
and Weis, S.,
Pre-images of extreme points of the numerical range, and applications,
Operators and Matrices 10:4, 1043-1058 (2016).
Special issue in memory of Leiba Rodman
arXiv
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Journal link
10) Weis, S.,
Maximum-entropy inference and inverse continuity of the numerical range,
Reports on Mathematical Physics 77:2, 251-263 (2016).
arXiv
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Journal link
9) Rodman, L.,
Spitkovsky, I. M.,
Szkoła, A.,
and Weis, S.,
Continuity of the maximum-entropy inference: Convex geometry and numerical ranges approach,
Journal of Mathematical Physics 57:1, 015204 (2016).
arXiv
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Journal link
8) Weis, S.,
Knauf, A.,
Ay, N.,
and
Zhao, M.-J.,
Maximizing the divergence from a hierarchical model of quantum states,
Open Systems & Information Dynamics 22:1, 1550006 (2015).
arXiv
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SFI Working Paper
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Journal link
7) Weis, S.,
Continuity of the maximum-entropy inference,
Communications in Mathematical Physics 330:3, 1263-1292 (2014).
arXiv
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MPI MIS Preprint
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Journal link
6) Weis, S.,
Information topologies on non-commutative state spaces,
Journal of Convex Analysis 21:2, 339-399 (2014).
arXiv
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MPI MIS Preprint
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Journal link
5) Weis, S.,
and Knauf, A.,
Entropy distance: New quantum phenomena,
Journal of Mathematical Physics 53:10, 102206 (2012).
arXiv
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MPI MIS Preprint
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Journal link
4) Weis, S.,
Duality of non-exposed faces,
Journal of Convex Analysis 19:3, 815-835 (2012).
arXiv
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MPI MIS Preprint
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Journal link
3) Weis, S.,
A note on touching cones and faces,
Journal of Convex Analysis 19:2, 323-353 (2012).
arXiv
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Journal link
2) Weis, S.,
Quantum convex support,
Linear Algebra and its Applications 435:12, 3168-3188 (2011).
arXiv
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Journal link (open access)
1) Voigt, I.
and Weis, S.,
Polyhedral Voronoi cells,
Contributions to Algebra and Geometry 51:2, 587-598 (2010).
arXiv
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Journal link (open access)
Refereed conference papers
5) Weis, S.,
Kippenhahn’s construction revisited,
accepted for publication in the proceedings of IWOTA 2022.
arXiv:2301.05802 [math.FA]
4)
Arora, A. S.,
Roland, J.,
and Weis, S.,
Quantum Weak Coin Flipping,
STOC 2019: Proceedings of the 51st Annual ACM SIGACT Symposium on Theory of
Computing, 2019, 205-216.
arXiv
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Final version (open access)
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Journal link
3) Weis, S.,
The MaxEnt extension of a quantum Gibbs family, convex geometry and geodesics,
AIP Conference Proceedings 1641, 173-180 (2015).
arXiv
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Journal link
2) Weis, S.,
Discontinuities in the maximum-entropy inference,
AIP Conference Proceedings 1553, 192-199 (2013).
arXiv
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Journal link
1) Bengtsson, I.,
Weis, S.,
and Życzkowski, K.,
Geometry of the set of mixed quantum states: An apophatic approach,
in: Geometric Methods in Physics,
P. Kielanowski, S. T. Ali, A. Odzijewicz, M. Schlichenmaier, T. Voronov (eds.),
Basel: Birkhäuser, 2013, 175–197.
arXiv
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MPI MIS Preprint
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Journal link
Academic theses
3) Weis, S.,
Exponential families with incompatible statistics and their entropy distance,
Doctoral Thesis, Erlangen, Germany, 2010.
Electronic Library (open access)
2) Weis, S.,
Invariants for the ideal boundary of a tree,
Diploma Thesis, Erlangen, Germany, 2004.
PDF file (639kB)
1) Weis, S.,
Dynamics on graphs,
Master Thesis, Bristol, UK, 2004.
PDF file (955kB)
Unpublished manuscripts
2) Weis, S.,
Decomposition of symmetric separable states and ground state energy of bosonic systems.
arXiv
1) Weis, S.,
On a theorem by Kippenhahn.
arXiv
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presentations: slides, videos, posters
Slides and videos
6) Choquet’s Theorem for Constrained Sets of Quantum States,
talk at the special session "Generalized Numerical Ranges, Operator Theory, and Quantum Information" at the 33rd
IWOTA, Krakow, Poland, September 2022,
slides (PDF, 564kB)
Video from a similar, longer talk at the MIAN online seminar "Quantum Probability, Statistics, Information", Steklov Mathematical Institute, Moscow, Russia, March 2021
5) Analysis of Generalized Gibbs States, talk at the conference
Entropy 2021: The Scientific Tool of the 21st Century,
Porto, Portugal,
May 2021,
slides (PDF, 1.1MB)
4) Quantum Weak Coin Flipping, talk at the
SUMA 2019 - Reunión anual de la UMA junto a la SOMACHI,
Mendoza, Argentina,
September 2019,
slides (PDF, 147kB)
3) Classification of joint numerical ranges of three hermitian matrices of size three, talk at
The Fourteenth Workshop on Numerical Ranges and Numerical Radii,
Munich, Germany,
June 2018,
slides (PDF, 1.8MB)
2) A new signature of quantum phase transitions from the numerical range,
talk at the conference
Entropy 2018: From Physics to Information Sciences and Geometry,
University of Barcelona, Spain,
May 2018,
slides (PDF, 268kB)
1) Stability of the set of quantum states, talk at the Workshop «Probabilistic techniques and Quantum Information Theory» at the Trimester «Analysis in Quantum Information Theory», Institut Henri Poincaré, October 2017,
video
Slides (PDF, 2.1MB) from a similar talk at the Pure Mathematics Research Centre, Queen’s University Belfast, UK, November 2017
Posters
2) The rI-Closure of an Exponential Family and Ground Spaces, poster presented at the Conference «Quantum Information Theory» at the Trimester «Analysis in Quantum Information Theory», Institut Henri Poincaré, December 2017,
poster (PDF, 863kB)
1) Mysterious Discontinuity of Quantum Correlation,
poster presented at the
Joint IAS-ICTP School on Quantum Information Processing,
Nanyang Executive Centre,
Nanyang Technological University, Singapore,
January 2016,
poster (PDF, 535kB)
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web profiles
arXiv,
Google Scholar,
LinkedIn,
MathSciNet,
MGP,
ORCiD,
ResearchGate,
Scopus,
Web of Science,
XING,
zbMATH
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trivia: Erdős number = 3, Einstein number = 4
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Weblinks zum Thema Klimawandel (in German) |
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BLOG: KlimaLounge von Stefan Rahmstorf, Professor für Physik der Ozeane
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Volker Quaschning, Professor für Regenerative Energiesysteme
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ins Deutsche übersetzte
Blog-Artikel von Skeptical Science
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Cranky Uncle, Spiel zur Stärkung der Abwehrkräfte gegen Falschinformationen (auch auf Deutsch und im Browser spielbar)
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