15th International Conference on Quantum Physics and Logic
QPL 2018

Important dates

• April 1: abstract submission
• April 6: paper submission
• April 30: application for student support
• May 11: notification of authors
• May 15: early registration deadline
• May 25: final papers ready
• June 3–7: conference

Invited speakers and invited tutorials

Invited speakers

• Dominic Horsman (University of Grenoble): "Surface code error correction and the ZX calculus" [abstract]

  In this talk I will give a gentle introduction to quantum surface codes, and to how the ZX calculus may be used as a high-level design and compilation language for them. I will show how using the ZX calculus simplifies an understanding of how the codes work, and in particular gives immediate access to the connection between 2D and 3D codes. Looking particularly at the operations of lattice surgery, I show how they form a direct model for the generators of the calculus in terms of 'splitting' and 'merging' operations. Interpreting the calculus in this operational way means coming to grips with probabilistic procedures, and I look at ways we can deal with this within ZX. Finally I show how having the calculus as a graphial language for error correction pays off in the compilation problem for quantum processes, and show how we get new operational procedures for protocols, including magic state distillation, from equational rewriting of the ZX diagrams.

• Debbie Leung (University of Waterloo): "Embezzlement-based nonlocal game that cannot be played optimally with finite amount of entanglement" [abstract]

  We first summarize recently found nonlocal games (with finite number of classical questions and answers) whose optimal winning probability can only be attained as a limit of strategies using arbitrarily high dimensional entangled states.

  Then, we focus on one such game, an explicit three-player game with very few classical questions and answers. This game is based on the coherent state exchange game introduced in arXiv:0804.4118, which in turns is based on embezzlement of entanglement due to van Dam and Hayden. We discuss the main ideas behind each of these ingredients, and how they can be put together to obtain a quantitative tradeoff in the winning probability vs the dimension of the entangled state shared by the players.

  Joint work with Zhengfeng Ji and Thomas Vidick, arXiv:1802.04926.

• Neil J. Ross (Dalhousie University): "Proto-Quipper: a circuit description language for quantum computing" [abstract]

  Quipper is a functional programming language for quantum computation which has been used to implement various elaborate quantum algorithms. At the moment, Quipper is implemented as an embedded language, whose host language is Haskell. One of the disadvantages to Quipper being an embedded language is that the Haskell type system, while providing many type-safety properties, is not in general strong enough to ensure the full type-safety of quantum programs.

  The Proto-Quipper language provides a foundation for the development of a stand-alone (i.e., non-embedded) version of Quipper. Like Quipper, Proto-Quipper acts as a circuit description language and provides the ability to treat circuits as data in order to manipulate them as a whole. However, Proto-Quipper is also designed to “enforce the physics”, in the sense that its type system would detect, at compile-time, programming errors that could lead to ill-formed or undefined circuits.

  I will start my talk with a brief introduction to quantum computing and a discussion of the design principles behind Quipper. I will then present Proto-Quipper and discuss open problems.

• Robert Spekkens (Perimeter Institute): "Experimentally bounding deviations from quantum theory in the landscape of generalized probabilistic theories" [abstract]

  Many experiments in the field of quantum foundations seek to adjudicate between quantum theory and speculative alternatives to it. This requires one to analyze the experimental data in a manner that does not presume the correctness of the quantum formalism. The mathematical framework of generalized probabilistic theories (GPTs) provides a means of doing so. We present a scheme for determining what GPTs are consistent with a given set of experimental data. It proceeds by performing tomography on the preparations and measurements in a self-consistent manner, i.e., without presuming a prior characterization of either. We illustrate the scheme by analyzing experimental data for a large set of preparations and measurements on the polarization degree of freedom of a single photon. We find that the smallest and largest GPT state spaces consistent with our data are a pair of polytopes, each approximating the shape of the Bloch Sphere and having a volume ratio of 0.977 ± 0.001, which provides a quantitative bound on the scope for deviations from quantum theory. We also demonstrate how our scheme can be used to bound the extent to which nature might be more nonlocal than quantum theory predicts, as well as the extent to which it might be more or less contextual. Specifically, we find that the maximal violation of the CHSH inequality can be at most 1.3% ± 0.1 greater than the quantum prediction, and the maximal violation of a particular noncontextuality inequality cannot differ from the quantum prediction by more than this factor on either side.

Tutorials

• Teiko Heinosaari (University of Turku): "Compatibility of quantum measurements and channels"
• Ciáran Lee (University College London): "Computation in a general physical setting" [abstract]

  The advent of quantum computing has challenged classical conceptions of which problems are efficiently solvable in our physical world. This raises the general question of what broad relationships exist between physical principles and computation. This tutorial will explore this question in the the operationally-defined framework of generalised probabilistic theories. To begin, the limits on computational power imposed by simple physical principles will be explored. After this, we shall investigate whether post-quantum interference is a resource for post-quantum computation. The tutorial will end with a conjecture asking whether quantum theory is optimal for computation in the landscape of generalised probabilistic theories satisfying a single physical principle.

Conference program

Talks began at 9am on Sunday morning, June 3, and ended at 5:30pm on Thursday afternoon, June 7. The poster session was on Monday evening, and the conference dinner was on Wednesday evening.

Click here for the schedule of talks. A compact PDF version of the schedule is also available.

Joint session with MFPS

On Wednesday afternoon, there was a joint special session with MFPS 2018 on quantum programming languages. The speakers were Neil J. Ross (Dalhousie), Craig Gidney (Google), Vadym Kliuchnikov (Microsoft), Jennifer Paykin (U. Penn), and Benoît Valiron (U. Paris-Saclay).

Best student paper award

At each QPL conference, an award for the best student paper is given at the discretion of the program committee. Papers eligible for the award are those where all the authors are students at the time of submission.

This year's best student paper award went to Matthew Amy for the paper "Towards large-scale functional verification of universal quantum circuits".

Travel to Canada

Most foreign nationals now need an electronic travel authorization before flying to Canada. This applies to all visa-exempt foreign nationals (for example, European citizens). It only costs $7 and can be done efficiently at the eTA website. The eTA requirement does not apply to U.S. citizens, nor to visitors who need an actual visa to travel to Canada.

Registration and local information

Registration is now closed. The registration fees were as follows:

• Regular participants: $110 (QPL only) or $130 (MFPS and QPL).
• Students: $70 (QPL only) or $90 (MFPS and QPL).
• Before May 15, there was an early registration discount of $10.

There was a joint QPL/MFPS conference dinner on Wednesday, June 6. The dinner took place at the University Club, 6259 Alumni Crescent (building C440 on the campus map).

For a list of hotels and other accommodation choices, see the Accommodations Page.

For information on how to get to Halifax from the airport, see the Airport Transportation Page.

All QPL talks were held in room 1020 of the Kenneth C. Rowe Management building at 6100 University Avenue (building E260 on the campus map). Here is a map of the area:

For those arriving on or before Saturday, there was an informal gathering at the Henry House Pub, 1222 Barrington Street (in the pub in the basement, not the formal dining room upstairs) on Saturday, June 2, starting at 6pm.

Student support

Graduate student participation is encouraged at QPL. Students will pay a reduced registration fee. We were also able to provide limited support for travel and accommodations to some students. If you are interested in this, please send a request to selinger@mathstat.dal.ca by April 30. Please also arrange for a letter of reference from your supervisor, or appropriate other person, to the same email address, explaining whether the student has access to funding from local sources and how much.

Submissions

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

• Original contributions consist of a 5-12 page extended abstract that provides sufficient evidence of results of genuine interest and enough detail to allow the program committee to assess the merits of the work. Submissions of works in progress are encouraged but must be more substantial than a research proposal.
• Extended abstracts describing work submitted/published elsewhere will also be considered, provided the work is recent and relevant to the conference. These consist of a 3 page description and should include a link to a separate published paper or preprint.

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

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=qpl2018.

This information is also available in the official Call for Papers.

Committees

Program Committee

• Giulio Chiribella (University of Oxford, co-chair)
• Peter Selinger (Dalhousie University, co-chair)
• Samson Abramsky (University of Oxford)
• Antonio Acín (Institute of Photonic Sciences)
• Richard Blute (University of Ottawa)
• Anne Broadbent (University of Ottawa)
• Dan Browne (University College London)
• Bob Coecke (University of Oxford)
• Ross Duncan (University of Strathclyde)
• Teiko Heinosaari (University of Turku)
• Chris Heunen (University of Edinburgh)
• Matthew Hoban (University of Oxford)
• Dominic Horsman (University of Durham)
• Bart Jacobs (Radboud University)
• Kohei Kishida (Dalhousie University)
• Aleks Kissinger (Radboud University)
• Joachim Kock (Universitat Autònoma Barcelona)
• Ciáran Lee (University College London)
• Matt Leifer (Chapman University)
• Martha Lewis (University of Amsterdam)
• Paul-André Melliès (CNRS, Université Paris Diderot)
• Mio Murao (University of Tokyo)
• Daniel Oi (University of Strathclyde)
• Ognyan Oreshkov (Université Libre de Bruxelles)
• Prakash Panangaden (McGill University)
• Anna Pappa (University of Edinburgh)
• Dusko Pavlovic (University of Hawaii)
• Simon Perdrix (CNRS, University of Grenoble)
• Paolo Perinotti (Università di Pavia)
• Neil J. Ross (Dalhousie University)
• Ana Belén Sainz (Perimeter Institute)
• Pawel Sobocinski (University of Southampton)
• Robert Spekkens (Perimeter Institute)
• Isar Stubbe (Université du Littoral)
• Benoît Valiron (Université Paris-Saclay)
• Jamie Vicary (University of Oxford)
• Mingsheng Ying (University of Technology Sydney)
• Margherita Zorzi (Università di Verona)

Local Organizers

• Neil J. Ross (Dalhousie University)
• Peter Selinger (Dalhousie University)

Steering Committee

• Bob Coecke (University of Oxford)
• Prakash Panangaden (McGill University)
• Peter Selinger (Dalhousie University)

Sponsors

We gratefully acknowledge financial support from:

• Atlantic Association for Research in the Mathematical Sciences (AARMS)
• U.S. Office of Naval Research (ONR)
• Dalhousie University Faculty of Science
• University of Waterloo, Institute for Quantum Computing (IQC)
• Perimeter Institute for Theoretical Physics
• Dalhousie University Office of the President
• Pacific Institute for the Mathematical Sciences (PIMS)
• Xanadu

Contact

For further information about QPL 2018, please email qpl2018@easychair.org.