Felix Leditzky

Research

My research focuses on quantum information theory, in particular the mathematical and computational aspects of quantum Shannon theory. Below is a list of topics that I am particularly interested in, together with some selected papers. See the next section for a more detailed list of my recent papers.

• Information theory: Quantum channel capacities, superadditivity in quantum information science, stabilizer formalism, quantum source coding, data processing inequalities, strong converse theorems, second order asymptotics, classical network information theory.
  Selected papers:
  • On the Duality of Teleportation and Dense Coding (2023)
  • The platypus of the quantum channel zoo (2022)
  • Generic nonadditivity of quantum capacity in simple channels (2022)
  • Playing Games with Multiple Access Channels (2019)
• Mathematical methods: Group theory, representation theory, matrix analysis, trace and operator inequalities.
  Selected papers:
  • Optimality of the pretty good measurement for port-based teleportation (2020)
  • Error Thresholds for Arbitrary Pauli Noise (2019)
  • Asymptotic performance of port-based teleportation (2018)
  • Data processing for the sandwiched Rényi divergence: a condition for equality (2016)
• Physics: Many-body quantum systems, tensor networks, multipartite entanglement.
  Selected papers:
  • Probing multipartite entanglement through persistent homology (2023)
  • Adaptive estimation of quantum observables (2021)
  • Quantum Codes from Neural Networks (2018)
• Optimization: semidefinite programming, global optimization techniques, neural networks.
  Selected papers:
  • On the separation of correlation-assisted sum capacities of multiple access channels (2022)
  • Quantum Codes from Neural Networks (2018)
  • Useful states and entanglement distillation (2017)

Papers

Below is a list of my most recent papers, including both preprints and published articles. For a full list, see arXiv.org, Google Scholar, or my CV.

Recent preprints

• On the distinguishability of geometrically uniform quantum states
  Juntai Zhou, Stefano Chessa, Eric Chitambar, Felix Leditzky
  arXiv preprint, 2025.
• Capacities of Entanglement Distribution From a Central Source
  Xinan Chen, Stefano Chessa, Ian George, Felix Leditzky, Eric Chitambar
  arXiv preprint, 2024.
• Localizing multipartite entanglement with local and global measurements
  Christopher Vairogs, Samihr Hermes, Felix Leditzky
  arXiv preprint, 2024.
• Multivariate Fidelities
  Theshani Nuradha, Hemant K. Mishra, Felix Leditzky, Mark M. Wilde
  arXiv preprint, 2024.
• Operational Nonclassicality in Quantum Communication Networks
  Brian Doolittle, Felix Leditzky, Eric Chitambar
  arXiv preprint, 2024.

Recently published papers

• Approximate Unitary k-Designs from Shallow, Low-Communication Circuits
  Nicholas LaRacuente, Felix Leditzky
  Published in the 16th Innovations in Theoretical Computer Science (ITCS) proceedings, 2025 (arXiv preprint).
  Presented as a long plenary talk at QIP 2025.
• Probing multipartite entanglement through persistent homology
  Greg Hamilton, Felix Leditzky
  Published in Communications in Mathematical Physics, 2024 (arXiv preprint).
  Presented as a contributed talk at Beyond IID 11.
• On the Duality of Teleportation and Dense Coding
  Eric Chitambar, Felix Leditzky
  Published in IEEE Transactions on Information Theory, 2024 (arXiv preprint).
  Presented as a contributed talk at TQC 2023.
• On the separation of correlation-assisted sum capacities of multiple access channels
  Akshay Seshadri, Felix Leditzky, Vikesh Siddhu, Graeme Smith
  Published in IEEE Transactions on Information Theory, 2023 (arXiv preprint).
  Presented as a contributed talk at ISIT 2022.
• Generic nonadditivity of quantum capacity in simple channels
  Felix Leditzky, Debbie Leung, Vikesh Siddhu, Graeme Smith, John A. Smolin
  Published in Physical Review Letters, 2023 (arXiv preprint).
  Presented as a contributed talk at QIP 2022.
• The platypus of the quantum channel zoo
  Felix Leditzky, Debbie Leung, Vikesh Siddhu, Graeme Smith, John A. Smolin
  Published in IEEE Transactions on Information Theory, 2023 (arXiv preprint).
  Presented as a contributed talk at QIP 2022.

Talks

Below you can find links to slides, videos and files for a selection of talks and posters I have presented at conferences and seminars. For a full list of conference and seminar talks and posters, see my full CV.

For the slides of my more recent presentations, I am explaining my workflow and what software I am using in this Twitter thread.

• Enhancing classical communication networks with quantum resources
  [slides] presented at 15th KCIK Symposium on Quantum Information, Sopot, Poland, May 2024.
• Probing multipartite entanglement through persistent homology
  [slides] presented at Beyond IID 2023, Tübingen, Germany, Jul 2023.
• On the duality of teleportation and dense coding
  [slides] presented (remotely) at TQC 2023, Aveiro, Portugal, Jul 2023.
• The platypus of the quantum channel zoo
  [slides] presented at the Weizmann Institute, Israel, Mar 2023.
• Symmetries and asymptotics of port-based teleportation
  [slides] presented at Quasar Seminar, University of Ottawa, Mar 2021.
  [slides] [video] presented at Tutte Colloquium, Department of Combinatorics and Optimization, University of Waterloo, Jul 2020.
• Playing games with multiple access channels
  [slides] [video] presented at TQC 2020, Riga, Latvia, Jun 2020 (conference held online).
  [slides] presented at ICTQT Seminar, University of Gdansk, Apr 2020.
  [video] presented at QuICS Seminar, University of Maryland, Nov 2019.
• Error thresholds for arbitrary Pauli noise
  [slides] [video] long talk presented as an extended talk at Beyond IID 2020, Stanford, CA, Nov 2020.
  [slides] [video] short talk presented at QIP 2020, Shenzhen, China, Jan 2020.
• Quantum codes from neural networks
  [slides] presented at Beyond IID 2019, Sydney, Australia, Jul 2019.
  [slides] presented at IQC quantum innovators conference, University of Waterloo, Oct 2018.
• Asymptotic performance of port-based teleportation
  [slides] [video] presented at Banff meeting on resource theories, Jul 2019.
  [poster] presented at Beyond IID 2018, Cambridge, UK, Jul 2018.
• Dephrasure channel and superadditivity of coherent information
  [slides] presented at SquInT 2019, Albuquerque, USA, Feb 2019.
  [slides] presented at Beyond IID 2018, Cambridge, UK, Jul 2018.
• Quantum and private capacities of low-noise channels
  [slides] presented at IEEE ITW, Kaohsioung, Taiwan, Nov 2017.
  [poster] presented at QIP 2017, Delft, Netherlands, Jan 2018.
• Useful states and entanglement distillation
  [slides] presented at Beyond IID 2017, Singapore, Jul 2017.
• Strong converse theorems using Rényi entropies
  [poster] presented at QIP 2017, Seattle, USA, Jan 2017.
• Relative entropies and their use in quantum information theory
  [slides] presented at JILA group meeting, CU Boulder, Mar 2017.
• Equality condition in the data processing inequality for the quantum relative entropy
  [slides] presented at CAKE Seminar, University of Cambridge, Feb 2016.

Teaching

I have taught the following courses at the University of Illinois Urbana-Champaign.

• Spring term 2024: Math 257 Linear Algebra with Computational Applications
• Spring term 2023: Math 595 Quantum channels (course website)
• Fall term 2022: Math 595 Representation-theoretic methods in quantum information theory (course website)
• Fall term 2021: Math 416 Abstract Linear Algebra (course website)
• Spring term 2021: Math 595 Quantum channels I: Representations and properties (course website)
• Spring term 2021: Math 595 Quantum channels II: Data-processing, recovery channels, and quantum Markov chains (course website)

Misc

Useful resources

• Lists of references to topics in mathematics and quantum information science close to my own research. These lists are mainly intended for students who are either interested in working with me, or just want to learn more about these topics for their own research.
• List of some essential papers in quantum information theory, compiled from a survey among colleagues on Twitter.
• 2022 STAQ Summer School tutorial on Quantum Communication
• Recorded lectures of my graduate course Quantum channels I: Representations and Properties.
• Recorded lectures of my graduate course Quantum channels II: Data-processing, recovery channels, quantum Markov chains.
• Lecture notes for my graduate course Quantum channels (combines Quantum channels I and II above).
• Lecture notes for my graduate course Representation-theoretic methods in quantum information theory.
• Recorded lectures of my undergraduate course Abstract Linear Algebra.

Editorial service

• Quantum: the open journal for quantum science
  I have recently joined the journal Quantum as an editor, handling submissions in quantum information theory, quantum Shannon theory, and papers focusing on mathematical methods in quantum information theory. Quantum is a so-called arXiv overlay journal, and grants complete open access to all its published papers. Please consider submitting your papers on the above topics to Quantum!
• Illinois Journal of Mathematics
  I'm also a member of the editorial board of the Illinois Journal of Mathematics (IJM). IJM is a peer-reviewed journal with a rich history covering all areas of mainstream mathematics. Please consider submitting your paper on mathematical topics in quantum information theory to IJM!

Conference & workshop organization

I have acted as an organizer for the following conferences and workshops:

• Bridging Quantum Information and Mathematical Physics, August 14-16, 2024, University of Cambridge.
  Organized together with Angela Capel, Nilanjana Datta and Mark M. Wilde.
• Beyond IID in Information Theory 12, July 29 to August 2, 2024, University of Illinois Urbana-Champaign.
  Organized together with Roy Araiza, Eric Chitambar, Marius Junge, and Amanda Young.
• QLA Meets QIT II, November 3-5, 2022, Illini Center, Chicago, IL.
  Organized together with Roy Araiza, Marius Junge, and Thomas Sinclair.
• TQC 2022, July 11-15, 2022, University of Illinois Urbana-Champaign.
  Organized together Eric Chitambar, Emily Edwards, Kelly C. Foster, Kim Gudeman.
• QIP 2019, January 14-18, 2019, University of Colorado Boulder.
  Organized together with Graeme Smith.
• Rocky Mountain Summit on Quantum Information, June 25-29, 2018, JILA, University of Colorado Boulder.
  Organized together with Mark M. Wilde and Graeme Smith.

About me

Short CV

Jan 2021 to present

Assistant Professor

Department of Mathematics, University of Illinois at Urbana-Champaign

Dec 2019 to Dec 2020

Postdoctoral Fellow

Institute for Quantum Computing, University of Waterloo & Perimeter Institute for Theoretical Physics

Nov 2016 to Nov 2019

Postdoctoral Research Associate

JILA, University of Colorado Boulder

Oct 2013 to Oct 2016

PhD (Mathematics)

DPMMS, University of Cambridge [thesis]

Oct 2006 to Apr 2013

Diploma^† (Physics)

University of Vienna [thesis]

Oct 2006 to Feb 2012

Diploma^† (Mathematics)

University of Vienna [thesis]

^† Roughly equivalent to BSc+MSc.

Before joining UIUC, I held postdoctoral positions at the Institute for Quantum Computing at the University of Waterloo and Perimeter Institute for Theoretical Physics from Dec 2019 to Dec 2020, and at JILA at the University of Colorado Boulder from Nov 2016 to Nov 2019. I obtained my PhD from the University of Cambridge in 2016 with a thesis on Relative entropies and their use in quantum information theory. My academic journey started in my hometown Vienna, Austria, where I obtained diploma degrees (≈ BSc + MSc) in Mathematics and Physics. Here is a link to my full academic CV.

Personal

I was born in Vienna, Austria. In my spare time I like to play the guitar, read, listen to music, play and watch (European) football, get better at cooking, and travel. Actually, I'm interested in pretty much everything.

Contact

Email: <lastname>@illinois.edu

Postal address:
Office 39, Computing Applications Building
605 E Springfield Ave
Champaign, IL 61820
USA