Aleks Kissinger

Aleks Kissinger

Associate Professor

E: aleks.kissinger@cs.ox.ac.uk

Themes:

Foundations, Structures, and Quantum

Biography

I am an Associate Professor of Quantum Computation. My research is in quantum information, quantum foundations, automated reasoning, category theory, graphical calculi, and graph rewriting. In particular, I am interested in applications of graphical languages to quantum circuit optimisation and the development of quantum causal models.

Papers

Selected publications can be found at the bottom of this page.

Click here to see all of my papers

...including preprints and slides from some talks.

Research & Updates

Coen Borghans wrote a masters thesis last year giving efficient 2-way translations between stabilizer ZX-diagrams and stabilizer subgroups. Here it is:
- ZX-Calculus and Quantum Stabilizer Theory
PyZX, our library for manipulating quantum circuits with the ZX-calculus, is now installable via pip. As a consequence, it is now easy to "run" ZX-diagrams on a real quantum computer using the IBM Quantum Experience. Check it out:

Also, here are some download stats for PyZX. Join the party! -->
I'm now on Twitter, but not much of a Tweeter (yet). Follow me if you like: @AleksKissinger
Louis Lemonnier completed a summer project with me last year, connecting the powerful path-sum technique for circuit verification to the ZH-calculus. Louis showed that the HH rule from path-sum is equivalent to a new rule called the Fourier hyperpivot, which has the twin benefits of being very useful for circuit simplification and sounding like a move from DragonBallZ.

UPDATE: There's now a paper about hyper-pivoting. Check out the preprint:
- Hypergraph simplification: Linking the path-sum approach to the ZH-calculus. Louis Lemonnier, John van de Wetering, and AK.
(Louis' original report is still available here.)
My student Sander Uijlen has passed his Phd defense! You can read his thesis here:
- Categorical approaches to computations in contextuality and causality
...or check out related journal papers on contextuality and causality.
PyZX is an open-source Python library for compilation, optimisation, and simulation of quantum circuits using the ZX calculus. To get some idea of what it's about, check out this Youtube video:

PyZX is...
Read a book!

Picturing Quantum Processes: A First Course in Quantum Theory and Diagrammatic Reasoning. Bob Coecke and Aleks Kissinger, Cambridge University Press

...which teaches quantum theory from the ground up, taking diagrams as the most fundamental tool. Order now from CUP, Amazon, or many other purveyors of fine printed goods. It has been the basis of a masters-level Quantum Computing course running in Oxford for about 5 years and another course running in Nijmegen in 2018 and 2019. If you are interested in running a similar course, get in touch with me.

To get some flavour of the book, you can check out Categorical Quantum Mechanics, part 1 and part 2, which give approximately the first 8 chapters in a somewhat condensed package.
I moved to Oxford! I'm happy to (re-)join the Quantum Group in Oxford's Department of Computer Science in 2019.
TikZiT 2 is now available for Windows, Linux, and macOS.

TikZiT is a super simple GUI editor for graphs and string diagrams. Its native file format is a subset of PGF/TikZ, which means TikZiT files can be included directly in papers typeset using LaTeX.
Our causality paper is the topic of a recent blog post on the n-category cafe. It also formed the basis of one of the four research threads at the 2018 Adjoint School of Applied Category Theory in Leiden.
I wrote an ERCIM news article about some of the exciting new developments in graphical calculus for quantum computation, notably the new completeness results for Clifford+T and universal quantum computation.
I co-organised a workshop with Pawel Sobocinski on string diagrams called STRING on Sept 8-9, satellite to FSCD in Oxford.
We organised the 14th International Conference in Quantum Physics and Logic (QPL) at Radboud in 2017, co-located with a satellite workshop on quantum structures run by IQSA. With 109 registered attendees, 5 invited talks, 4 tutorials, and a total of 67 contributed talks across QPL and IQSA, it was a huge success!
I was a keynote speaker at IQSA 2016, July 10-16 in Leicester, UK.
I gave a tutorial on process theories and graphical languages at QPL 2016, June 6-10 in Glasgow, UK.
My student David Quick has passed his viva! His PhD thesis is called:
- !-Logic: First-Order Reasoning for Families of Non-Commutative String Diagrams
Check out Quantomatic, a tool for (semi)automated reasoning with diagrammatic languages.