Events

Organized by Hubert HANSEN from Ip2i at the Université Ouverte de Lyon I

Two public lectures (website here):

1. The Quantum <-> Gravity Interface - La Physique à l'Interface Gravitation <-> Quantique [pdf]

2. Strings or Loops in black holes' heart ? - Strings ou Loops au coeur des trous noirs ? [pdf]

Organized by the Université Ouverte de Lyon I et l'Ip2i

La relativité générale est notre théorie actuelle de la gravitation, confirmée expérimentalement par une multitude de mesures en astrophysique. Je débuterai avec la notion de relativité en physique, qui reflète le fait que différents observateurs peuvent mesurer des distances et des durées différentes pour les mêmes évènements. Je montrerai comment cela mène à un espace-temps à géométrie courbe et ouvre la porte à comprendre la gravitation d'une manière totalement différente que la loi de la gravitation universelle de Newton. Cela nous amènera à une phénoménologie nouvelle, à base de lentilles gravitationnelles, de dilatation temporelle, de trous noirs et d'ondes gravitationnelles. Plein d'effets fascinants que l'on peut observer pour de vrai aujourd'hui!

  Poster    -   Programme Complet

• Course #3 of the Lecture Series Quantum Gravity Gathering - Report

Spinfoam path integrals for Quantum Gravity
- a local picture of quantum geometry from topological field theory

At the crossroads of several approaches to quantum gravity, Spinfoams propose a discrete path integral for quantum general relativity built from topological field theory. With the spectrum of geometric operators directly read from the representation theory of the local symmetry group, they can be interpreted as a quantized version of Regge calculus and can be understood as implementing the dynamics of quantum states geometry in loop quantum gravity. I will explain the basics of the formalism, the motivations, the mathematical framework and the main tools. In three space-time dimensions, the spinfoam quantization of 3d gravity is given by the Turaev-Viro topological invariant, which is intimately related to the quantization of Chern-Simons theory. I will explain in particular how the spinfoam amplitudes solve the Wheeler-de Witt equation, implement the invariance under 3d diffeomorphisms (despite being formulated in a discretized space-time) and lead to a quasi-local version of holography. In four space-time dimensions, general relativity can be formulated as an almost-topological theory and I will explain how the existing spinfoam models introduce a sea of topological defects to re-create the gravitational degrees of freedom from a topological path integral. Finally, I will show how spinfoams are naturally defined in terms of group field theory, which are generalized tensor models, and the prospects that this opens. I will conclude with the main challenges and open lines of research of the field.

• Seminar Quasi-local holography in 3d quantum gravity

Since the idea appeared in black hole physics, the concept of holography has become a guiding principle for quantum gravity. It is the notion that the dynamics of the geometry of a region of space-time can be entirely encoded in a theory living on its boundary. Although such holographic dualities have been well-developed in an asymptotical context, it remains a challenge to realize it exactly at finite distances. I will draw a possible route in 3d quantum gravity, by showing a duality between the Ponzano-Regge path integral for 3d quantum gravity as a topological field theory and the 2d (inhomogeneous) Ising model. This leads to an intriguing geometrical interpretation of the Ising critical couplings and opens the door to a possibly rich interplay between 3d quantum gravity and 2d condensed matter built out of holographic dualities.

Organizing Committee:
J Borissova, A Castro, G Franzmann, E Livine, L Petruzziello, D Rajbhandari, VH Satheeshkumar

The Basics of Quantum Gravity online school is a series of lectures on the key concepts and techniques involved in the research of Quantum Gravity. It is dedicated to young researchers who are tackling this great challenge in theoretical physics. The goal is to bridge several paths and approaches to quantum gravity and provide young researchers with the tools to work on all of these frameworks and utilize various formalisms.

The launching lecture for this event will take place on May 16th. The event will run throughout Europe's spring and summer of 2023, featuring lectures on String Theory, Loop Gravity, the perturbative and non-perturbative renormalization flow of General Relativity, and quantum information in Gravity. Additional lectures on other topics will be planned for the fall and winter.

This is an initiative by the International Society for Quantum Gravity. It will be followed by a series of workshops on more advanced topics.

Lecture videos available on the IsQG YouTube channel

Organisée par l'Université de la Polynésie Française et l'Association ProScience

La mécanique quantique et la relativité générale sont nées il y a un siècle, pour décrire le monde microscopique des particules et le monde des étoiles et galaxies. Ces théories peuvent sembler mystérieuses, comme suspendues dans un brouillard de concepts étranges et d’équations techniques. On les côtoie néanmoins au quotidien, sans même sans rendre compte, dans le système GPS, les laser ou l’électronique. Aujourd’hui on entend parler de la révolution des ordinateurs quantiques ou des mesures d’ondes gravitationnelles créées par des collisions de trous noirs. Quelles en seront les enseignements, les applications ?

 Au cours de cette conférence et du débat qui la suivra, les questions de base de la mécanique quantique seront abordées et trouveront une réponse dans un langage simple. 

Scientific Organizing Committee :
M Geiller, E Livine, A Perez, S Speziale

Local Organizing Committee :
J Münch, S Viollet, S Speziale, A Rignon-Bret, G Odak, S Ribisi

The Quantum Gravity teams of the CPT Marseille and the ENS Lyon are happy to welcome you to the Loops '22 Summer School in Marseille from 11. July to 15. July 2022. After a virtual School last year, we are looking forward to organizing this school in person at the Campus Luminy of the Aix-Marseille-Université in the beautiful parc national des calanques.

The school covers the basics of Loop Quantum Gravity (LQG) and related topics, with pedagogical introductions to some of the current research directions. The lectures will introduce spin network states, the canonical and spin foam approaches to the quantum dynamics, applications to the early universe and black holes, quantum information techniques for quantum gravity, numerical methods and possible numerical lab experiments on quantum superposition of geometries.

The school aims to introduce these sparkling and vibrant research topics. It is open to both students and researchers with no a priori background in background independent quantum gravity, and to those who know already the basics and want to be brought up to date.

The school is followed by the Loops '22 conference on Loop Quantum Gravity at the ENS Lyon.
The school is supported by the Quantum Information Structure of Spacetime (QISS) consortium.

Organizors : E Livine, P Dona

This year the LQG summer school is online. We shall not have the pleasure of gathering, getting to know new people directly, and learning from one-to-one conversations, but we will do the best to make this enjoyable and fruitful.

The school covers the basics of Loop Quantum Gravity and related topics and introductions to hot research topics. These include the basics of the spin network and spin foam formalisms, applications to the early universe and black holes, group field theory and random geometry formalisms, quantum information techniques for quantum gravity, numerical methods and possible lab experiments on quantum superposition of geometries.

The school aims to introduce this sparkling and vibrant research topics. It is meant for students and researchers with no a priori background in background independent quantum gravity. All the lectures are available on the dedicated YouTube channel.

Lectures on Fundamentals:

1. Loop Quantum Gravity, spin networks and spin foams by Prof. M Dupuis

2. Black Holes: Classical and Quantum Theory by Prof. A Perez

3. Group Field Theory and random geometries by Prof. E Wilson-Ewing and Prof. V Bonzom

4. QFT on Curved space-time and applications to LQC by Prof. I Agullo and Dr. M Martin-Benito

5. Quantum Information for Quantum Gravity by Prof. E Bianchi and Dr. F Giacomini

6. Symmetries and Conserved Charges in General Relativity by Dr. M Geiller

Lectures on Advanced Topics

1. Black to White Hole Transition by Prof. C Rovelli

2. Numerical Methods in LQG by Dr. P Dona

3. Effective Spinfoams and Renormalization by Prof. H Haggard and Dr. S Asante

4. QG Experiments by Dr. Andrea Di Baggio

5. Gravitational Waves and Prospects for QG by Prof. D Nichols

6. The Infrared Triangle in Quantum Gravity by Prof. A Strominger

Organizors : E Livine, M Geiller

During the Covid-19 pandemy, we turn our group meetings at the ENS Lyon into an international series dubbed The Non-Local Quantum Gravity Seminar, covering hot topics in quantum gravity. Taking place on the Zoom Platform and broadcasted on a dedicated YouTube channel, it allowed for our group and collaborators to stay in touch and discuss about the latest progress in the field.