Preface

This volume contains the proceedings of the 21st International Conference on Quantum Physics and Logic (QPL 2024). The conference was held from 15 to 19 July 2024, at Instituto de Ciencias de la Computación in Buenos Aires, Argentina, co-organized by Universidad Nacional de Quilmes and Universidad de Buenos Aires.

Quantum Physics and Logic is a series of conferences that brings together academic and industry researchers working on the mathematical foundations of quantum computation, quantum physics, and related areas. The main focus is on the use of algebraic and categorical structures, formal languages, type systems, semantic methods, and other mathematical and computer science techniques applicable to the study of physical systems, physical processes, and their composition. Work applying quantum-inspired techniques and structures to other fields (such as linguistics, artificial intelligence, and causality) is also welcome.

The QPL 2024 conference solicited four kinds of submissions: proceedings submissions, non-proceedings submissions, poster submissions, and programming tool submissions.

Proceedings submissions were papers required to provide sufficient evidence of results of genuine interest. Authors of accepted proceedings submissions were given the opportunity to present their work during a talk at the conference, and these papers were included in the proceedings of QPL 2024. No other types of submissions were considered for inclusion in the proceedings. Non-proceedings submissions consisted of a three-page summary, together with a link to a separate published paper or preprint. Authors of accepted non-proceedings submissions were invited to present their work in the form of a talk during the conference. Poster submissions consisted of a three-page abstract of (partial) results or work in progress, and authors of accepted poster submissions were invited to present their work during the poster session. Programming tool submissions consisted of three-page descriptions of programming tools or frameworks. Authors of accepted programming tool submissions were given the opportunity to present their software during a dedicated "Tool Session".

These proceedings contain 9 contributed papers selected for publication by the Program Committee. Papers submitted to QPL undergo a review process managed by members of the Program Committee (PC). The vast majority of submissions received at least three reviews. The selection of accepted papers was done through the EasyChair conference management system, following consideration of the submitted reviews and, where necessary, discussion among the PC members. The review process was single-blind: the identity of the authors was revealed to the reviewers, but not vice versa. PC members could invite external experts to serve as subreviewers and participate in discussions of the submissions they reviewed.

A total of 135 submissions (excluding withdrawals and retractions) were considered for review by the PC. QPL 2024 had 59 accepted submissions in the non-proceedings track and 9 accepted submissions in the proceedings track. Most of the talks were presented during parallel sessions, but a selection of talks was presented during plenary sessions in the mornings. The program also included a poster session with 30 accepted posters, and one session dedicated to showcasing the accepted programming tool submission. There was also an industry session where industrial sponsors of QPL 2024 were given the opportunity to present their companies. The industry session consisted of three talks—one by Quantinuum, one by the Technology Innovation Institute, and one by Quandela, all of them platinum sponsors.

The QPL 2024 conference featured an award for Best Student Paper. Papers eligible for the award were those in which all the authors were students at the time of submission. The PC decided to award the Best Student Paper award for QPL 2024 to Nicolas Heurtel (Quandela, Université Paris-Saclay, CNRS, ENS Paris-Saclay, Inria, Laboratoire Méthodes Formelles) for his paper "A complete graphical language for linear optical circuits with finite-photon-number sources and detectors".

The official website of the conference is https://qpl2024.dc.uba.ar, and it contains a lot of relevant information about QPL 2024.

The Program Committee consisted of 50 members: Barbara Amaral, Pablo Arrighi, Miriam Backens, Rui Soares Barbosa, Alessandro Bisio, Titouan Carette, Ulysse Chabaud, Giulio Chiribella, Bob Coecke, Alejandro Díaz-Caro (co-chair), Ross Duncan, Pierre-Emmanuel Emeriau, Stefano Gogioso, Amar Hadzihasanovic, Chris Heunen, Matty Hoban, Federico Holik, Dominic Horsman, Emmanuel Jeandel, Martti Karvonen, Kohei Kishida, Aleks Kissinger, Ravi Kunjwal, Martha Lewis, Shane Mansfield, Simon Martiel, Mio Murao, Ognyan Oreshkov, Anna Pearson, Simon Perdrix, Robert Rand, Neil Ross, Mehrnoosh Sadrzadeh, Ana Belén Sainz, Carlo Maria Scandolo, John Selby, Peter Selinger, Sonja Smets, Pawel Sobocinski, Isar Stubbe, Benoît Valiron, John van de Wetering, Augustin Vanrietvelde, V. Vilasini, Renaud Vilmart, Juliana Kaizer Vizzotto, Quanlong Wang, Alexander Wilce, Vladimir Zamdzhiev (co-chair), and Margherita Zorzi.

The Organising Committee consisted of four members: Guido Bellomo, Alejandro Díaz-Caro (chair), Santiago Figueira, and Federico Holik.

The QPL Steering Committee consisted of Bob Coecke, Ana Belén Sainz, and Peter Selinger.

We wish to thank all the members of the PC for their work in selecting the program of QPL 2024. We also thank all external subreviewers for their help and the authors for their submissions to QPL 2024. Thanks are also due to Ana Belén Sainz for making a few decisions on papers for which the PC co-chairs were not available. We are grateful to the EPTCS team for their help in preparing the proceedings of the conference. We also thank the members of the Organising Committee for their help in setting up the conference and the collaborators Martín Bosyk and Octavio Malherbe. We thank the student helpers who volunteered to assist us: Carlos Miguel Soto, Malena Ivnisky, Marcos Lammers, Nicolás Ciancaglini, Nicolás Alberto Monzón, Rafael Romero, and Santiago Cifuentes. Finally, we thank the QPL Steering Committee for their support and all the people who have contributed to the success of QPL 2024.

QPL 2024 received financial support from Quantinuum, the Technology Innovation Institute, and Quandela, as well as grants RD315 from CONICET and UBACyT-RC-12-2024 from Universidad de Buenos Aires.

July 2024,
Alejandro Díaz-Caro and Vladimir Zamdzhiev