June 7th-11th, 2021 in Gdańsk, Poland

18th International Conference on
Quantum Physics and Logic

Quantum Physics and Logic

is an annual conference that brings together researchers working on mathematical foundations of quantum physics, quantum computing, and related areas, with a focus on structural perspectives and the use of logical tools, ordered algebraic and category-theoretic structures, formal languages, semantical methods, and other computer science techniques applied to the study of physical behaviour in general. Work that applies structures and methods inspired by quantum theory to other fields (including computer science) is also welcome.

Previous QPL events were held in Paris (2020 - online), Orange (2019), Halifax (2018), Nijmegen (2017), Glasgow (2016), Oxford (2015), Kyoto (2014), Barcelona (2013), Brussels (2012), Nijmegen (2011), Oxford (2010), Oxford (2009), Reykjavik (2008), Oxford (2006), Chicago (2005), Turku (2004), and Ottawa (2003).

Paper submission deadline

March 12th, 2021

Author notification

May 7th, 2021

Final papers ready

May 28th, 2021

Registration deadline

June 2nd, 2021


June 7th to 11th, 2021

Note that the paper submission and author notification deadlines are both one month later than initially advertised.

All deadline times are Anywhere on Earth (UTC-12).

REMARK: Due to the COVID-19 pandemic, the conference might be shifted to online-only closer to the date. We will keep you posted!

Please make this conference a welcoming space for everyone. We ask you to use your real name when logging into any of our systems. Our conference is dedicated to providing a harassment-free conference experience for everyone, regardless of gender, gender identity and expression, age, sexual orientation, disability, physical appearance, body size, race, ethnicity, religion (or lack thereof), or scientific opinion. We do not tolerate harassment of community members in any form.

All communication should be appropriate for a professional audience including people of many different backgrounds. Sexual language and imagery is not appropriate for any venue this conference will be held in, whether physical or virtual. If you are being harassed, notice that someone else is being harassed, or have any other concerns, please contact a member of conference staff immediately. If a participant engages in harassing behaviour, the conference organisers may take any action they deem appropriate, including warning the offender or expulsion from the conference.

The dedicated safety and inclusion team will oversee reports of Code of Conduct violation. The team can be contacted at qpl.safety.inclusion@gmail.com , and its members are:

  • Dominic Horsman (University of Oxford)
  • Shane Mansfield (Quandela)
  • Ana Belén Sainz (ICTQT, University of Gdańsk)

Harassment may include but is not limited to:

  • Offensive comments related to gender, gender identity and expression, sexual orientation, disability, physical appearance, body size, race, age, religion, or technology choices;
  • Sexual language and images in any workshop platform;
  • Deliberate intimidation, stalking, or following;
  • Harassing photography or recording;
  • Sustained disruption of talks or other events;
  • Inappropriate sexual attention;
  • Advocating for, or encouraging, any of the above behaviour.



Scientific sessions

5 day event, 5 invited talks, 40 contributed talks, 20 posters, 100 participants.

Industry session

The industry session will consist of an evening event starting with a presentation session shared by selected companies. These presentations will be followed by an industry fair, hosted together with the poster session.

Virtual participation

QPL 2021 will also feature a virtual component, following the success of QPL 2020. Virtual participation will be enabled, talks will be streamed, and a virtual platform for scientific discussions will be implemented.

Abstracts and Recordings

The abstracts of the talks presented at QPL 2021 have been compiled into a single Book Of Abstracts (pdf).

Recorded talks are available at the QPL 2021 Gdańsk Youtube Channel.

Event Calendar

This calendar reflects the (local) time at which the talks took place, adjusted to the nearest quarter hour.

Anna Jencova

Part II of the earlier talk

Pub Quiz!

Marcin Wierzbinski

Genuinely quantum SudoQ and its cardinality

Kuntal Sengupta

Quantum Bell Nonlocality is Entanglement

Roberto Dobal Baldijão

Quantum Darwinism and the spreading of classical information in non-classical theories

Christophe Chareton

A Deductive Verification Framework for Circuit-building Quantum

Konstantinos Meichanetzidis

Compositional Models of Meaning on a Quantum Computer

Carlo Maria Scandolo

Dynamical entanglement

Martin Plávala

Jordan products of quantum channels and their compatibility

Matty Hoban

Invited Talk: Quantum networks and composition self-test all entangled states

Marek Żukowski and John Selby

Welcome to QPL2021 Gdansk

Martha Lewis

Invited Tutorial: Natural Language Processing and Quantum Theory

Xiaoning Bian and Sarah Li

Generators and Relations for On(ℤ[1/2]) and Uₙ(ℤ[1/2, i])

Nitica Sakharwade

Hierarchy of Theories with Indefinite Causal Structures: A Second Look at the Causaloid Framework

Guillaume Aubrun

Entangleability of cones

Robin Kaarsgaard

Bennett and Stinespring, Together at Last

David Schmid

The Stabilizer Subtheory Has a Unique Noncontextual Model

Robert Booth

F-flow: determinism in measurement-based quantum computation with qudits

Arthur Parzygnat

Conditional distributions for quantum systems

Titouan Carette

Graphical Language with Delayed Trace: Picturing Quantum Computing with Finite Memory

Alastair Abbott & Victoria Wright

Characterising and bounding the set of quantum behaviours in contextuality scenarios/Bounding and simulating contextual correlations in quantum theory

John van de Wetering

Constructing quantum circuits with global gates

Máté Farkas

Mutually unbiased bases and symetric informationally complete measurements in Bell experiments

David Schmid

The interplay of entanglement and nonlocality demystified: developing a new branch of entanglement theory

Alexis Toumi

Diagrammatic Differentiation for Quantum Machine Learning

Samuel Kuypers

On non-commuting qubits, with an application to the closed time-like curve problem.

Wataru Yokojima

Consequences of preserving reversibility in quantum superchannels

Paweł Mazurek

Thermodynamics of Minimal Coupling Quantum Heat Engines

Mariami Gachechiladze

Quantifying causal influences in the presence of a quantum common cause

Titouan Carette

Quantum Algorithms and Oracles with the Scalable ZX-calculus

Flaminia Giacomini

Invited Talk: A no-go theorem on the nature of the gravitational field beyond quantum theory

Alexandre Clément

Coherent control and distinguishability of quantum channels via PBS-diagrams

Hippolyte Dourdent

Semi-Device-Independent Certification of Causal Nonseparability with Trusted Quantum Intputs

Ariel Bendersky

Invited Tutorial: Descriptive complexity as a tool for quantum correlations

Anna Jencova

Invited Talk: Incompatibility in general probabilistic theories, generalized spectrahedra, and tensor norms

Leevi Leppäjärvi

Measurement simulability: overview and applications

Frank Fu, Kohei Kishida and Peter Selinger

Linear Dependent Type Theory for Quantum Programming Languages

Poster session and industry showcase

Matt Wilson

Causality in Higher Order Physics

Matthew Graydon

Composites and Categories of Euclidean Jordan Algebras with Superselection Sectors

Will Simmons

Relating measurement patterns to circuits via Pauli flow and Pauli Dependency DAGs

Industry Showcase featuring CQC, Google, Topos Institute, & Unitary Fund

Marco Túlio Quintino

Success-or-draw: A strategy allowing repeat-until-success in quantum computation

Giannicola Scarpa

Agreement between observers: a physical principle?

John van de Wetering

The ZH-calculus: completeness and extensions

Hlér Kristjánsson

Invited Talk: A second-quantised Shannon theory

Paulo Cavalcanti

A generalised probabilistic theory featuring post-quantum steering

Invited Speakers

Invited academic talks

Matty Hoban (Cambridge Quantum Computing & Goldsmiths, University of London): Quantum networks and composition self-test all entangled states

Self-testing is a method for certifying the production of quantum states with making minimal assumptions about the devices. In recent years a plethora of quantum states have been shown to be amenable to self-testing, but the question of whether an arbitrary quantum state can be self-tested, and up to which transformations, is an open question. I will show a method for self-testing an arbitrary (pure) quantum state, up to local transformations and global complex conjugation. The method is compositional in nature, utilising simple quantum networks with EPR pairs distributed throughout. I will also indicate how the global complex conjugation symmetry can be removed if the sources of EPR pairs are assumed to be independent. This is from joint work with Ivan Šupić, Joe Bowles, Marc-Olivier Renou and Antonio Acín.

Anna Jencova (Mathematical Institute, Slovak Academy of Sciences): Incompatibility in general probabilistic theories, generalized spectrahedra, and tensor norms

Incompatibility of quantum measurements is one of the fundamental non-classical features of quantum theory. As a crucial ingredient in many quantum information protocols, incompatibility has become an important resource for quantum information theory, similar to entanglement. It is therefore a natural question how much of this resource is available in a given situation, characterized by the dimension of the quantum system, number of measurements and their outcomes.

It is known that incompatibility is not restricted to quantum mechanics but is present in any non-classical theory, in the framework of general probabilistic theories (GPT). This broader setting allows us to study and characterize incompatibility of measurements from different perspectives and using different mathematical tools. In this talk, we first concentrate on two-outcome measurements (or effects) and characterize their incompatibility in terms of tensor norms on Banach spaces. For measurements with more outcomes this does not seem possible, so we use a characterization by a GPT generalization of free spectrahedra and their inclusion constants, and by extensibility and separability properties of certain positive maps. As an application we explore compatibility regions and degrees of several GPT's of interest, in particular, we find a tight lower bound on incompatibility of any number of qubit effects.

The talk is based on a joint work with Andreas Bluhm and Ion Nechita, arxiv:2011.06497.

Flaminia Giacomini (Perimeter Institute): A no-go theorem on the nature of the gravitational field beyond quantum theory

Recently, table-top experiments involving massive quantum systems have been proposed to test the interface of quantum theory and gravity. In particular, the crucial point of the debate is whether it is possible to conclude anything on the quantum nature of the gravitational field, provided that two quantum systems become entangled due to solely the gravitational interaction. Typically, this question has been addressed by assuming an underlying physical theory to describe the gravitational interaction, but no systematic approach to characterise the set of possible gravitational theories which are compatible with the observation of entanglement has been proposed. Here, we introduce the framework of Generalised Probabilistic Theories (GPTs) to the study of the nature of the gravitational field. This framework has the advantage that it only relies on the set of operationally accessible states, transformations, and measurements, without presupposing an underlying theory. Hence, it provides a framework to systematically study all theories compatible with the detection of entanglement generated via the gravitational interaction between two non-classical systems. Assuming that such gravitationally mediated entanglement is observed we prove a no-go theorem stating that gravity cannot simultaneously satisfy the following conditions i) it is a theory with no faster-than-light signalling; ii) it mediates the gravitational interaction via a physical degree of freedom; iii) it is classical. We further show what the violation of each condition implies, and in particular, when iii) is violated, we provide examples of non-classical and non-quantum theories which are logically consistent with the other conditions.

Hlér Kristjánsson (University of Oxford): A second-quantised Shannon theory

Traditionally, quantum Shannon theory has focused on scenarios where the internal state of the information carriers is quantum, while their trajectory is classical. However, as illustrated by the iconic double slit experiment, quantum particles can also propagate in a quantum superposition along multiple trajectories. In this talk, I shall discuss the recent extension of quantum Shannon theory to a second level of quantisation, where both the information and its propagation in spacetime is treated quantum mechanically.

First, I shall discuss our theoretical framework for formalising these scenarios, showing that when a single particle propagates through a superposition of multiple paths, the joint action of the independent noisy processes on each path is uniquely determined by their individual action on the vacuum state [G Chiribella & HK, Proc R Soc A 475.2225, 2019]. Secondly, I shall show how the same formalism can be extended further to describe the transmission of a quantum particle at a superposition of alternative moments in time [HK, W Mao, G Chiribella, arXiv:2004.06090, 2020]. When successive uses of a transmission line are correlated, we find that contrary to classical intuition, these correlations can be probed by a single quantum particle propagating at a superposition of times, and exploited to carry a larger amount of information per channel use.

Finally, I shall show that the mathematical structures arising in the physical scenarios of the second-quantised Shannon theory cannot be adequately described within the standard framework of quantum circuits. Consequently, I shall provide a brief introduction to our extended framework of routed quantum circuits [A Vanrietvelde, HK, J Barrett, arXiv:2011.08120, 2020], the details of which are left for another talk.

Invited tutorials

Ariel Bendersky (CS departments, FCEyN, Universidad de Buenos Aires, Argentina CONICET (National Scientific and Technical Research Council), Argentina): Descriptive complexity as a tool for quantum correlations

In this tutorial I will review some tools from theoretical computer science and descriptive complexity and show how can they be used to provide new insights into quantum foundations. In particular, I will show how Kolmogorov complexity and algorithmic randomness can be used in the context of quantum non-locality to analyse syntactic properties of sequences of experiments and provide a different notion of non-locality [1], new loopholes [2], new insight into the nature of quantum correlations [3] and open the doors into new informational principles for correlations.

  1. [1] Wolf, S. (2015). Nonlocality without counterfactual reasoning. Physical Review A, 92(5), 052102.
  2. [2] Bendersky, A., De La Torre, G., Senno, G., Figueira, S., & Acín, A. (2016). Algorithmic pseudorandomness in quantum setups. Physical review letters, 116(23), 230402.
  3. [3] Bendersky, A., Senno, G., De La Torre, G., Figueira, S., & Acin, A. (2017). Nonsignaling deterministic models for nonlocal correlations have to be uncomputable. Physical review letters, 118(13), 130401.
Martha Lewis (University of Bristol): Natural Language Processing and Quantum Theory

Natural language processing (NLP) is a field of artificial intelligence that looks at representing natural language in a way that computers can take in, process, and interpret. One branch of NLP has had astonishing success over the last decade or so by representing words as vectors in vector spaces. A natural question then arises: can the tools and techniques of quantum theory be usefully applied in the area of NLP? In this tutorial I will give an overview of the use of vector semantics in NLP and an outline of applications of quantum techniques within NLP. These will include a principled approach to word and phrase composition in NLP, use of quantum structures such as density matrices for text representation, and an overview of how to move towards implementing these techniques on quantum computers.

Invited industry talks

Call for papers

Prospective speakers are invited to submit one (or more) of the following:

Proceedings submissions consist of a 5-12 page extended abstract. Only proceedings-track submissions are eligible to be published in Electronic Proceedings in Theoretical Computer Science (EPTCS) after the conference.

Non-proceedings submissions consist of a 3 page extended abstract and a link to a separate published paper, pre-print, or an attached draft.

Poster submissions consist of a 1-3 page abstract and may contain a link to a separate published paper or pre-print. Submission of partial results of work in progress is encouraged.

Submissions should be prepared using LaTeX, and must be submitted in PDF format. Use of the EPTCS style is encouraged. Submission is done via EasyChair: https://www.easychair.org/conferences/?conf=qpl2021

The Conference proceedings will be published in Electronic Proceedings in Theoretical Computer Science (EPTCS) after the conference. Only "proceedings submissions" are eligible to be published in the proceedings.

The deadline was the end of March the 12th "Anywhere on Earth" (UTC -12), and has now passed.


Registration closed on the 2nd of June. Please email qpl2021@gmail.com if you would still like to participate.


Programme chairs

Programme committee

Inclusivity and safety team

Steering committee

Local organisers

Website managers

Venue & contact

The 18th edition of QPL will be hosted by the International Centre for Theory of Quantum Technologies (ICTQT), at the University of Gdańsk, Poland.

The conference will feature five days of scheduled talks by invited and contributed speakers, a poster session, and an industry session. QPL 2021 will also feature a virtual component, following the success of QPL 2020. Virtual participation will be enabled, talks will be streamed, and a virtual platform for scientific discussions will be implemented. More details comming soon.

We are available via email: QPL2021@gmail.com

If you are interested in more details about the event, want to know more about the sponsorship opportunities, please download the QPL2021 PDF Brochure.


Wita Stwosza 63

80-308 Gdańsk

Tel: + 48 585 235 180