Quantum foundations concerns the conceptual and mathematical underpinnings of quantum theory. In particular, we search for novel quantum effects, consider how to interpret the formalism, ask where the formalism comes from, and how we might modify it. Research at Perimeter Institute is particularly concerned with reconstructing quantum theory from more natural postulates and reformulating the theory in ways that elucidate its conceptual structure. Research in the foundations of quantum theory naturally interfaces with research in quantum information and quantum gravity.
Format results

26 talksCollection Number C19049
Talk


TBA
Fabio Costa University of Queensland

Causality in Qbism
Jacques Pienaar University of Massachusetts Boston


TBA
Linqing Chen Université Libre de Bruxelles

Indefinite causal order without postselection
Katja Ried TNG Technology Consulting

TBA
Robert Mann University of Waterloo

Time reference frames and gravitating quantum clocks
Esteban Castro Ruiz Université Libre de Bruxelles (ULB)


PSI 2019/2020  Quantum Theory (Branczyk/Dupuis)
14 talksCollection Number C19038Talk

PSI 2019/2020  Quantum Theory (Dupuis)  Lecture 14
Maïté Dupuis Perimeter Institute for Theoretical Physics

PSI 2019/2020  Quantum Theory (Dupuis)  Lecture 13
Maïté Dupuis Perimeter Institute for Theoretical Physics

PSI 2019/2020  Quantum Theory (Dupuis)  Lecture 12
Maïté Dupuis Perimeter Institute for Theoretical Physics

PSI 2019/2020  Quantum Theory (Dupuis)  Lecture 11
Maïté Dupuis Perimeter Institute for Theoretical Physics

PSI 2019/2020  Quantum Theory (Dupuis)  Lecture 10
Maïté Dupuis Perimeter Institute for Theoretical Physics

PSI 2019/2020  Quantum Theory (Dupuis)  Lecture 9
Maïté Dupuis Perimeter Institute for Theoretical Physics

PSI 2019/2020  Quantum Theory (Dupuis)  Lecture 8
Maïté Dupuis Perimeter Institute for Theoretical Physics



Foundations of Quantum Mechanics
17 talksCollection Number C18020Talk


Counterfactual communication protocols
Lev Vaidman Tel Aviv University


Models and Tests of Quantum Theory and Gravity
Adrian Kent University of Cambridge



Measures of Preparation Contextuality
Matthew Leifer Chapman University

Observables and (no) time in quantum gravity
Bianca Dittrich Perimeter Institute for Theoretical Physics


Algorithmic Information, Induction and Observers in Physics
17 talksCollection Number C18007Talk


Argumentation, Conditionals, and the Use of Information Theoretic Concepts in Bayesianism
Stephan Hartmann LudwigMaximiliansUniversitiät München (LMU)

Being vs. Happening: information from the intrinsic perspective of the system itself
Larissa Albantakis University of Wisconsin–Madison

Causal inference rules for algorithmic dependences and why they reproduce the arrow of time
Dominik Janzing Max Planck Institute for Biological Cybernetics

From observers to physics via algorithmic information theory
Markus Müller Institute for Quantum Optics and Quantum Information (IQOQI)  Vienna

Observer Localization in Multiverse Theories
Marcus Hutter Australian National University

Can quantum states be understood as Bayesian states of belief?
Wayne Myrvold Western University

Introduction to Algorithmic Information Theory and Tutorial
Marcus Hutter Australian National University


Observers in Quantum and Foil Theories
11 talksCollection Number C18006Talk

Microcanonical thermodynamics in general physical theories
Carlo Maria Scandolo University of Oxford
PIRSA:18040091 
Agents, Subsystems, and the Conservation of Information
Giulio Chiribella The University of Hong Kong (HKU)
PIRSA:18040089 

Inadequacy of modal logic in quantum settings
Lidia del Rio ETH Zurich  Institut für Theoretische Physik
PIRSA:18040087 
Quantum theory cannot consistently describe the use of itself
Renato Renner ETH Zurich  Institut für Theoretische Physik
PIRSA:18040085 

Motility of the internalexternal cut as a foundational principle
Robert Spekkens Perimeter Institute for Theoretical Physics
PIRSA:18040073 
From observers to physics via algorithmic information theory II
Markus Müller Institute for Quantum Optics and Quantum Information (IQOQI)  Vienna
PIRSA:18040080


Talk

From 3D TQFTs to 4D models with defects
Bianca Dittrich Perimeter Institute for Theoretical Physics

Hopf algebras and parafermionic lattice models
Joost Slingerland National University of Ireland

Frobenius algebras, Hopf algebras and 3categories
David Reutter Universität Hamburg




Interacting Hopf monoids and Graphical Linear Algebra
Pawel Sobocinski University of Southampton

Introduction to CQM
Ross Duncan University of Oxford


Contextuality: Conceptual Issues, Operational Signatures, and Applications
23 talksCollection Number C17027Talk

How to go from the KS theorem to experimentally testable noncontextuality inequalities
Ravi Kunjwal Funds for Scientific Research  FNRS


Contextuality and Temporal Correlations in Quantum Mechanics
Otfried Guhne University of Siegen


Contextuality as a resource for quantum computation: the trouble with qubits
Juan BermejoVega Freie Universität Berlin

Contextuality and noncontextuality in (qudit) quantum computation
Dan Browne University College London (UCL)  Department of Physics & Astronomy


Contextuality and quantum simulation
Stephen Bartlett University of Sydney


Experimental Quantum Foundations
5 talksCollection Number C16034Talk

Experimental implementation of quantumcoherent mixtures of causal relations
Robert Spekkens Perimeter Institute for Theoretical Physics



Singlephoton test of HyperComplex Quantum Theories
Lorenzo Procopio Universität Wien

Direct experimental reconstruction of the Bloch sphere

Michael Mazurek Institute for Quantum Computing (IQC)

Matthew Pusey University of York



Concepts and Paradoxes
11 talksCollection Number C16008Talk





Protective Measurement and Ergodicity
Yakir Aharonov Chapman University

Sudden Sharp Forces and Nonlocal Interactions
Yakir Aharonov Chapman University




Indefinite Causal Structure
26 talksCollection Number C19049There has been a surge of interest in indefinite causal structure the idea that cause and effect can no longer be sharply distinguished. Motivated both by experimentation with quantum switches and quantum gravity there can be situations in which there is no matterofthefact as to what the causal structure of spacetime is. This meeting will bring together workers in Quantum Foundations and Quantum Gravity in both theoretical experimental physics to discuss the state of the art of current research and set new directions for this emerging subdiscipline.

PSI 2019/2020  Quantum Theory (Branczyk/Dupuis)
14 talksCollection Number C19038PSI 2019/2020  Quantum Theory (Branczyk/Dupuis) 
Foundations of Quantum Mechanics
17 talksCollection Number C18020The foundations of quantum mechanics have been revitalized in the past few decades by three developments: (i) the influence of quantum computation and quantum information theory (ii) studies of the interplay between quantum theory and relativity particularly the analysis of indefinite causal structure and (iii) proposals to reconstruct quantum theory from basic axioms. There have also been very interesting developments in understanding and classifying no=locality and contextuality using tools from sheaf theory and cohomology as well as operator algebras and category theory. The International Congress of Mathematical Physics is a natural forum for the discussion of these topics. In the past there have been satellite workshops on topics like Operator algebras and quantum statistical mechanics which also address fundamental issues. The modern study of quantum foundations is very much influenced and informed by mathematics: sheaf theory and cohomology category theory information theory convex analysis in addition to the continuing interest in operator algebras and functional analysis. The aim of the workshop is to bring together researchers who have made substantial contribution to the recent developments. The workshop will be held at Perimeter Institute over a five day period from July 30

Algorithmic Information, Induction and Observers in Physics
17 talksCollection Number C18007Our universe is of astonishing simplicity: almost all physical observations can in principle be described by a few theories that have short mathematical descriptions. But there is a field of computer science which quantifies simplicity namely algorithmic information theory (AIT). In this workshop we will discuss emerging connections between AIT and physics some of which have recently shown up in fields like quantum information theory and thermodynamics. In particular AIT and physics share one goal: namely to predict future observations given previous data. In fact there exists a gold standard of prediction in AIT called Solomonoff induction which is also applied in artificial intelligence. This motivates us to look at a broader question: what is the role of induction in physics? For example can quantum states be understood as Bayesian states of belief? Can physics be understood as a computation in some sense? What is the role of the observer i.e. the agent that is supposed to perform the predictions? These and related topics will be discussed by a diverse group of researchers from different disciplines.

Observers in Quantum and Foil Theories
11 talksCollection Number C18006Foil theories sometimes called mathematically rigorous science fiction describe ways the world could have been were it not quantum mechanical. Our understanding of quantum theory has been deepened by contrasting it with these alternatives. So far observers in foil theories have only been modeled implicitly for example via the recorded probabilities of observing events. Even when multiagent settings are considered these agents tend to be compatible in the classical sense that they could always compare their observations. Scenarios where agents and their memories are themselves modeled as physical systems within the theory (and could in particular measure each other as in Wigner's friend experiment) have not yet been considered. In this workshop we will investigate which foil theories allow for the existence of explicit observers and whether they allow for paradoxes in multiagent settings such as those found in quantum theory. We will also investigate which interpretations of quantum theory would equally well interpret the foil theories and which interpretations are truly quantum. We will gain a deeper understanding of how this can happen by discussing appropriate definitions observers in these theories and seeing how such observers learn about their environment.

Hopf Algebras in Kitaev's Quantum Double Models: Mathematical Connections from Gauge Theory to Topological Quantum Computing and Categorical Quantum Mechanics
18 talksCollection Number C17029The Kitaev quantum double models are a family of topologically ordered spin models originally proposed to exploit the novel condensed matter phenomenology of topological phases for faulttolerant quantum computation. Their physics is inherited from topological quantum field theories, while their underlying mathematical structure is based on a class of Hopf algebras. This structure is also seen across diverse fields of physics, and so allows connections to be made between the Kitaev models and topics as varied as quantum gauge theory and modified strong complementarity. This workshop will explore this shared mathematical structure and in so doing develop the connections between the fields of mathematical physics, quantum gravity, quantum information, condensed matter and quantum foundations.

Contextuality: Conceptual Issues, Operational Signatures, and Applications
23 talksCollection Number C170272017 marks 50 years since the seminal 1967 article of Kochen and Specker proving that quantum theory fails to admit of a noncontextual model. Despite the fact that the KochenSpecker theorem is one of the seminal results concerning the foundations of quantum theory, there has never been a large conference dedicated to the subject. The 50year anniversary of the theorem seems an opportune time to remedy this oversight. Furthermore, in the last decade, there have been tremendous advances in the field. New life has been breathed into the subject as old conceptual issues have been reexamined from a new informationtheoretic perspective. Importantly, there has been great progress in making the notion of noncontextuality robust to noise and therefore experimentally testable. Finally, there is mounting evidence that the resource that powers many quantum advantages for information processing is contextuality. In particular, it has been shown to underlie the possibility of universal quantum computation. Many groups worldwide are actively engaged in advancing our knowledge on each of these fronts and in deepening our understanding of the distinction between quantum and classical theories through the lens of contextuality. Through this conference, we aim to bring together leading researchers in the field in order to develop a broader perspective on the issues, draw connections between different approaches, foster a more cohesive community, and set objectives for future research.

Experimental Quantum Foundations
5 talksCollection Number C16034Experimental Quantum Foundations 