Seminar at CPHT February 27th Friday
Speaker: Emma Bonvarlet (Bachelor)
Time: 11:00 am, February 27th Friday
Location: Salle de Conférence Jean Lascoux
Title: A precision tradeoff: balancing entanglement and variance in noisy quantum simulations
Le Centre de Physique Théorique (CPHT) réunit des chercheurs dont les activités couvrent un large spectre de la Physique, tant dans ses aspects fondamentaux qu'appliqués.
Le CPHT est une unité mixte de recherche (UMR 7644) du Centre National de la Recherche Scientifique (CNRS) et de l’Ecole polytechnique. Au niveau du CNRS, il est rattaché à l’Institut de physique. Le CPHT a également un partenariat avec le Collège de France.
Le CPHT, dirigé par Marios Petropoulos, directeur de Recherche au CNRS, est implanté sur le campus de l’Ecole Polytechnique à Palaiseau, dans le bâtiment 6 et dans l'aile 0 du bâtiment 5. Le secrétariat se situe dans le Bâtiment 6, bureaux 06.1046 et 06.1045.
Adresse postale :
CPHT
Ecole Polytechnique
91128 Palaiseau cedex
France
Tél. Secrétariat : 01 69 33 42 01
Pour écrire un email à un membre du laboratoire : prenom.nom@polytechnique.edu
Speaker: Emma Bonvarlet (Bachelor)
Time: 11:00 am, February 27th Friday
Location: Salle de Conférence Jean Lascoux
Title: A precision tradeoff: balancing entanglement and variance in noisy quantum simulations
Speaker: Antoine Rignon-Bret
Time: 14:00 pm, Feb 25th Wednesday
Location: Salle de Conférence Louis Michel
Title: The second law: from Lindblad equation to black holes
Abstract: In this talk, I will present how techniques from quantum information theory and quantum thermodynamics can be used to derive the second law of thermodynamics for quantum fields. I will begin with the case of a finite quantum system undergoing a Markovian evolution driven by an infinite bath, whose dynamics are governed by the Lindblad equation and whose thermodynamic properties are well understood. Building on this framework, I will show how a natural generalization allows us to extend these methods to the thermodynamics of quantum fields defined on causal horizons. Unlike finite quantum systems, quantum field theory admits many unitarily inequivalent Hilbert spaces, each constructed from a distinct choice of vacuum state. I will argue that these different vacua can be interpreted as corresponding to different reservoirs driving the dynamics. In particular, I will demonstrate how Wall’s proof of the generalized second law fits naturally within this framework, and how analogous thermodynamic laws describing black hole thermodynamics emerge for asymptotic observers. These laws correspond to different thermodynamic potentials associated with distinct vacuum states, such as the Boulware, Hartle–Hawking, and Unruh vacua.
Zoom Link: https://ecolepolytechnique.zoom.us/j/97688194627?pwd=5byaoDaJ9J0kubMRXYKA09xWHfwxUK.1
Speaker: Michal P. Heller
Time: 14:00 pm, Feb 18th Wednesday
Location: Salle Jean Lascoux
Title: Quasinormal perspective on nonthermal fixed points
Abstract: I will present nonthermal fixed points as paradigmatic far from equilibrium weak coupling phenomena characterised by a self-similar evolution in time. I will then discuss what strong coupling perspective based on the quasinormal modes insights into holographic thermalization and hydrodynamics can teach us about nonthermal fixed points. Based on 2307.07545, 2502.01622 and 2504.18754.
Speaker: Mitchell Woolley
Time: 16:00 pm, Feb 2th Wednesday
Location: Salle de Conférence Louis Michel
Title: The W-algebra bootstrap of 6d (2,0) theories (Continued.....)
Abstract: We outline progress toward the superconformal bootstrap of the mixed correlator bootstrap of 6d (2,0) SCFTs. The first step was achieved in [2506.08094], where we used the conjectured cohomological reduction of 6d (2,0) SCFTs to W-algebras to extract an infinite set of protected mixed correlator CFT data. To that end, we explicitly construct the W_g algebras of 6d (2,0) theories of type g={A,D} and impose Jacobi identities on generator OPEs to fix CFT data. We uplift this data and the twisted correlators to 6d and show how our CFT data is organized along conformal Regge trajectories. As an application, we demonstrate the consistency of this information with protected higher derivative corrections in the M-theory holographic dual on AdS_7 x S^4/Z_o.
La journée des thèses du CPHT a lieu le jeudi 29 janvier 2026 dans la salle de conférence Jean Lascoux à partir de 9H00.
Speaker: André Pinheiro
Time: 14:00 pm, Jan 28th Wednesday
Location: Salle de Conférence Louis Michel
Title: Holographic fluids with higher-form symmetries
Abstract: Higher-form symmetries are ubiquitous in physics. In this talk, I focus on the case where they are continuous and encode the conservation of extended objects. Applications include elasticity, superfluidity and phases of electromagnetism. Using holography, we explore effective descriptions of systems with the simplest case of a single higher-form symmetry. For energies well below temperature, these descriptions admit a (potentially extended) hydrodynamic regime. We verify this explicitly by studying AlAdS black branes charged under higher-form potentials. In particular, we compute quasinormal modes, starting with the low-density limit. Then, we focus on the bulk dual of a viscoelastic system and analyse instabilities for different equilibrium states corresponding to isotropic crystalline phases.
Spaeker: Rodrigo Olea
Time: 14:30 pm, Jan 23th Friday
Location: Salle de Conférence Louis Michel
Title: Holographic Weyl Anomaly and Kounterterms
Abstract: The addition of Kounterterms leads to a finite action for Einstein gravity for asymptotically AdS spaces with a conformally flat boundary. In that sense, it provides a partial renormalization scheme when compared to standard holographic techniques. However, Kounterterms method has the advantage that they can be written down in an arbitrary dimension. In this talk, we show how to extract holographic information on conformal anomalies from the variation of odd-dimensional Einstein-AdS plus Kounterterms.
Spaeker: Sebastian Waeber
Time: 15:30 pm, Jan 21th Wednesday
Location: Salle de Conférence Louis Michel
Title: Driven holographic turbulence and random gravity
Abstract: The fluid/gravity correspondence, the duality between black hole dynamics in Anti-de Sitter space and hydrodynamics, may be used to geometrize turbulent flow. Our goal is to translate the long-standing problem of explaining anomalous scaling exponents of fluid velocity structure functions into a language of gravity. We study the fluid phase of conformal matter driven by a randomly fluctuating gravitational potential, numerically solving the evolution of a black hole in Anti-de Sitter space with a fluctuating, stochastic boundary metric. Subtleties regarding the fluid's compressibility in this set up are discussed. We observe a scaling behavior of the energy power spectrum that is consistent with compressible flow and compute the energy dissipation and the fluid velocity distribution. We identify observables in the dual gravity theory corresponding to higher moments of the averaged energy dissipation which help to map anomalous scaling exponents to covariant quantities defined on the dual horizon.
Time: 15:30 pm, Jan 14th Wednesday
Location: Salle de Conférence Louis Michel
Martin Pico (Universidad Autonoma de Madrid)
Title: Classifying consistent truncations from Exceptional Generalised Geometry
Abstract: Consistent truncations have proven to be one of the main tools to study low-dimensional effective theories of string theories. In this talk, I will discuss how new U-duality covariant formulations of higher-dimensional supergravities, Exceptional Generalised Geometries (EGG) and Exceptional Field Theories (ExFT), can be used to classify the possible consistent truncations that can be obtained from such higher-dimensional supergravities.

Des chercheurs du Centre de Physique Théorique proposent un formalisme théorique qui offre une description de la gravité et des ondes gravitationnelles au « bord » de l’Univers.
Dans une Lettre récemment publiée dans Physical Review Letters [1], une équipe de chercheurs dirigée par Marios Petropoulos (directeur de recherches CNRS, CPHT), composée d’Adrien Fiorucci, Simon Pekar et Matthieu Vilatte (anciens ou actuels membres du CPHT), propose une dérivation intrinsèquement définie sur le bord des équations dynamiques de la gravitation d’Einstein dans le cadre de l’holographie en espace-temps plat. Cette approche repose sur la géométrie carrollienne et constitue l’aboutissement de méthodes développées de longue date au CPHT, où existe une expertise reconnue dans ce domaine. Cette avancée théorique ouvre de nouvelles perspectives vers l’unification de la relativité générale et de la mécanique quantique.
[1] Adrien Fiorucci, Simon Pekar, P. Marios Petropoulos and Matthieu Vilatte, Carrollian-Holographic Derivation of Gravitational Flux-Balance Laws, Phys.Rev.Lett. 135, 261602, https://journals.aps.org/prl/abstract/10.1103/qv17-ks32
Communiqué de presse de l’École polytechnique
Image : vue d'artiste d'un espace-temps émergeant de manière holographique. Crédit : A. Fiorucci.