Quantum gravity is concerned with unifying Einstein's general theory of relativity with quantum theory into a single theoretical framework. At Perimeter Institute, researchers are actively pursuing a number of approaches to this problem including loop quantum gravity, spin foam models, asymptotic safety, emergent gravity, string theory, and causal set theory. We are also particularly interested in experimental implications of these different proposals. As the aim is a unification of the laws of physics into a single theory, the search for quantum gravity overlaps with other areas such as cosmology, particle physics and the foundations of quantum theory.
Format results

15 talksCollection Number C19039
Talk

PSI 2017/2018  Quantum Gravity (Dupuis)
15 talksCollection Number C17052Talk

PSI 2017/2018  Quantum Gravity  Lecture 15
Laurent Freidel Perimeter Institute for Theoretical Physics

PSI 2017/2018  Quantum Gravity  Lecture 14
Maïté Dupuis Perimeter Institute for Theoretical Physics

PSI 2017/2018  Quantum Gravity  Lecture 13
Maïté Dupuis Perimeter Institute for Theoretical Physics

PSI 2017/2018  Quantum Gravity  Lecture 12
Maïté Dupuis Perimeter Institute for Theoretical Physics

PSI 2017/2018  Quantum Gravity  Lecture 11
Maïté Dupuis Perimeter Institute for Theoretical Physics
PIRSA:18040093 
PSI 2017/2018  Quantum Gravity  Lecture 10
Maïté Dupuis Perimeter Institute for Theoretical Physics

PSI 2017/2018  Quantum Gravity  Lecture 9
Maïté Dupuis Perimeter Institute for Theoretical Physics

PSI 2017/2018  Quantum Gravity  Lecture 8
Maïté Dupuis Perimeter Institute for Theoretical Physics


The Path Integral for Gravity
18 talksCollection Number C17057Talk

Covariant observables and (quantum) extension theorems
Sumati Surya Raman Research Institute


Intrinsic and extrinsic points of view
Lucien Hardy Perimeter Institute for Theoretical Physics

The Path Integral of Unmodular Gravity
Roberto Percacci SISSA International School for Advanced Studies

QuantumMechanical Aspects of Quantum Cosmology
Jonathan Halliwell Imperial College London

Why should (and why can) the path integral serve as the basis for quantum theory?
Rafael Sorkin Perimeter Institute for Theoretical Physics

Consistency of a quantum cosmological bounce
Steffen Gielen University of Sheffield

The NoBoundary Proposal: Alive and Well
Thomas Hertog Katholieke Universiteit Leuven


Quantum Black Holes in the Sky?
34 talksCollection Number C17055Talk


What does a quantum black hole look like to the Event Horizon Telescope?
Avery Broderick University of Waterloo


LongLived Inverse Chirp Signals from CoreCollapse in Massive ScalarTensor Gravity
Ulrich Sperhake California Institute of Technology

Growing BlackHole Hair in Extensions of General Relativity
Helvi Witek University of Cambridge

Remarks on cosmic censorship and its possible violations
Roberto Emparan Institucio Catalana de Recerca I Estudis Avancats (ICREA)  Universitat de Barcelona


Qubit Model for Black Hole Evaporation without Firewalls
Don Page University of Alberta


Lights, Sounds, Action in Strong Field Gravity.
Collection Number C17062 
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


It from Qubit Summer School
62 talksCollection Number C16003Talk

Toy Holography
Daniel Harlow Massachusetts Institute of Technology (MIT)

Quantum Gravity and Quantum Chaos
Stephen Shenker Stanford University

Eigenstate Thermalization Hypothesis
Markus Müller Institute for Quantum Optics and Quantum Information (IQOQI)  Vienna

Modular hamiltonians in 2d CFT
John Cardy University of California System

Why physicists should care about the complexity zoo
Adam Buland Massachusetts Institute of Technology

Tensor Network Holography

Vijay Balasubramanian University of Pennsylvania

Xiaoliang Qi Stanford University

Brian Swingle University of Maryland, College Park


Black Hole Information Paradox  2
Daniel Harlow Massachusetts Institute of Technology (MIT)

Quantum NP and the Complexity of Ground States
Dorit Aharonov Hebrew University of Jerusalem


Quantum Information in Quantum Gravity II
30 talksCollection Number C15041Talk

The Complexity and (Un)Computability of Quantum Phase Transitions
James Watson University of Maryland, College Park

Introduction to Quantinuum and TKET
Mark Jackson Leiden University

Quantum simulation of Z2 lattice gauge theory with dynamical matter
Fabian Grusdt LudwigMaximiliansUniversitiät München (LMU)

NLTS Hamiltonians from good quantum codes
Anurag Anshu Harvard University

Positivity, negativity, entanglement, and holography
Mukund Rangamani University of California System

3D Holography: from discretum to continuum
Bianca Dittrich Perimeter Institute for Theoretical Physics

Quantum Fisher metric in field theory and gravity
Nima Lashkari McGill University

Wormholes and Complexity
Adam Brown Stanford University


PSI 2019/2020  Relativity (Kubiznak)
15 talksCollection Number C19039PSI 2019/2020  Relativity (Kubiznak) 
PSI 2017/2018  Quantum Gravity (Dupuis)
15 talksCollection Number C17052PSI 2017/2018  Quantum Gravity (Dupuis) 
The Path Integral for Gravity
18 talksCollection Number C17057Over the past three decades, the idea of a path integral over geometries, describing gravity in various dimensions, has become increasingly central to many areas of theoretical physics, including string and Mtheory, holography and quantum aspects of black holes and cosmology.
In each of these areas, the path integral is frequently invoked as a formal device although, as practitioners will admit, except in very special cases the basic formula remains undefined. Typically, classical saddle points are discussed, whether real or complex, but the required integrals are left unperformed.
This state of affairs is untenable because it leaves the theory on a shaky footing and hence does not permit a sound comparison of theoretical predictions with observations. The time has come to critically reassess the foundational ideas of the path integral for gravity, including its definition, evaluation and interpretation; to identify problems with
existing uses and claims based on it, and to seek improvements. The workshop will focus on the continuum theory and its semiclassical limit, with applications to cosmology, black holes and holography. In particular, the notion of a “Euclidean path integral” for a “wavefunction of the universe” will be addressed.To this effect we intend to revisit discussion of “quantum geometrodynamics” from the path integral viewpoint and to pursue various applications. The developments in this direction that took place in the late 1970's and early 1980's were not incorporated in subsequent efforts, where the emphasis shifted to using a classical background with quantum fluctuations superimposed on it, a split which although useful in particular approximations can hardly be imagined to lie at the foundation of the theory. The revival of the discussion of the foundation of the path integral for gravity is made timely, we believe, by the introduction of new global methods such as PicardLefschetz theory.
The format of the workshop will be unusual. For the first three days, the mornings will begin with a longer, introductory lecture by each of the three organisers, setting out some of the foundational issues. This will be followed by shorter lectures by the participants, tackling the same foundational questions. The morning lectures, held in the Bob room, will be open to all Perimeter residents and visitors. They will be recorded and made available for viewing on PIRSA. Afternoons will be devoted to friendly and informal discussions, with participants invited to offer short contributions which follow up or develop points raised in the mornings, within a relaxed and highly conducive environment. Participation in these afternoon discussion sessions, as well as social events associated with the workshop, will be limited to registered workshop participants. The last two days of the workshop will be an opportunity for participants to continue discussions on topics which emerge as of greatest general interest, as well as to follow up in smaller groups on technical points or new ideas.

Quantum Black Holes in the Sky?
34 talksCollection Number C17055The past decade has witnessed significant breakthroughs in understanding the quantum nature of black holes, with insights coming from quantum information theory, numerical relativity, and string theory. At the same time, astrophysical and gravitational wave observations can now provide an unprecedented window into the phenomenology of black hole horizons. This workshop seeks to bring together leading experts in these fields to explore new theoretical and observational opportunities and synergies that could improve our physical understanding of quantum black holes.

Lights, Sounds, Action in Strong Field Gravity.
Collection Number C17062With LIGO/VIRGO in operation and detecting gravitational waves, the era of gravitational wave astronomy is upon us. In anticipation of further observations, this workshop will discuss the physics, astrophysics, and observational prospectsas well as challengesin gravitational wave sources including black holes, neutron stars, and other fascinating objects, in both the near and long term.

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.


Quantum Information in Quantum Gravity II
30 talksCollection Number C15041Quantum Information in Quantum Gravity II