The center for Theoretical Physics (CPHT) at Ecole Polytechnique gathers research scientists working in diverse domains of fundamental and applied Physics. The overall coherence is assured by the corpus of common, transposable, mathematical and numerical methods.
CPHT is a joint research unit of CNRS and Ecole Polytechnique, and has a partnership with the Collège de France. His director is Jean-René Chazottes, Senior Researcher at CNRS.
CPHT is on the campus of Ecole Polytechnique, buildings 5 and 6. The reception offices are located in building 6 , offices 06.1046 and 06.1045.

Postal Address :
Ecole Polytechnique 
91128 Palaiseau cedex 

Secretary phone number : 01 69 33 42 01 (from abroad: +33 169 334 201)

Write an email to someone at CPHT :  :



The 8th CPHT Young Researchers Seminar will be held on February 10, 2023 at 3:00 p.m. in the Louis Michel Conference Room with two presentations given by :

Adrien Loty (CPHT, CNRS, École Polytechnique) : Constraints on Maximally Supersymmetric String Theories

Adrián Gómez Pueyo (CPHT, CNRS, École Polytechnique) : Nonlinear Phononics: (Transiently) Breaking the Symmetry of a Crystal

The seminar will be followed by a high tea.



PhD Student

Resarch activities at CPHT: Condensed Matter

Research interests: Topology, Quantum Information, Condensed Matter, Theoretical Physics, Quantum Physics, Many-Body physics

Thesis:  "Topological Materials, Semimetals and Quantum Information"

AdvisorKaryn Le Hur


The objective of this thesis is to study the topological and physical properties of a new class of topological semimetals recently discovered in the group. These semimetals exhibit fractional topological properties due to the particular geometry of their band structure, involving quantum entanglement properties in the Brillouin zone. The first part of this thesis will consist in studying these quantum properties in order to identify the nature of the protection of this topological phase of matter. During this first part of the thesis, we will also be interested in identifying possible experimental protocols, including light-matter interactions protocols, with aim of experimental demonstration of these fractional topological phases by characterizing the properties of thermodynamic and transport observables within these topological phases. Particular attention will be paid to the effects of interactions on the topology of the system. Eventually, the goal is to develop new theoretical and numerical tools for the systematic study and characterization of these fractional topological phases of matter for technological purposes with links to entanglement and quantum information.



Address CPHT, Ecole Polytechnique, 91128 Palaiseau cedex, France
Phone number 01 69 33 42 76
Office Aile zéro, Office 1018




The publication of Alexander Friedmann's seminal papers in 1922 marked the birth of modern cosmology. In order to celebrate its centenary, the Friedmann Endowment will fund various scientific actions over the next few years, covering the wide range of themes associated with cosmology, at École Polytechnique and partner institutions, in collaboration with the Foundation of Ecole Polytechnique. The Friedmann Colloquium will be a flag activity, organized by the Physics Department and aimed at a general audience of scientists and science students.

For its first edition of the Friedmann Colloquium, Dr. Frank Eisenhauer from the Max Planck Institute for Extraterrestrial Physics, Munich (Garching) will speak about : THE GALACTIC CENTER BLACK HOLE, THE EFFECTS OF GENERAL RELATIVITY, AND HOW TO OBSERVE THEM

Monday, December 5, 2022 at 6:00 pm in Becquerel Lecture Hall of Ecole polytechnique

Abstract found at :

The program and the videos of the conferences of the Physics Department are available on the Department website:

About the Alexander Friedmann Endowment
In 1922 Alexander Friedmann (1888-1925) published a seminal paper, which triggered the advent of modern cosmology. In order to celebrate its centenary, the Alexander Friedmann Endowment supports various scientific activities, covering the wide range of subjects associated with cosmology, at Ecole Polytechnique and its partner institutions. Among these activities, the Friedmann Colloquium is a general seminar addressing an audience of scientists and science students.
Scientific committee : Silke Biermann (CPHT), Jean-René Chazottes (CPHT), Mathieu de Naurois (LLR), Marios Petropoulos (CPHT), Sébastien Renaux-Petel (IAP), Yves Sirois (LLR).



The students conference is organized this year on Friday, November 25, Becquerel amphitheatre.

speakers and titles

9h15 - 10h45

1-Jean-Gabriel Thiriet (Stability analysis of ablation flows in inertial-confinement fusion: receptivity)
2-Adrien Loty (Unitarity constraints on maximally supersymmetric string theories)
3-Theophile Truchis (Metastability and state clustering in evolutionary games)
4-Zhaoxuan Zhu (Thermodynamic phase diagram of two-dimensional bosons in a quasicrystal potential)
5-Matthieu Vilatte (A dive into the Carrollian world)
6-Majdouline Borji (Perturbative renormalization of boundary field theory)
7-Victor Franken (Entanglement builds bridges (in quantum gravity)

11h15 - 12h30

8-Ephraim  Bernhardt (Topology of spin-1/2 systems and relations to a « quantum dynamo)
9-Dylan Bansard-Tresse (Extreme value laws and hitting times for dynamical systems)
10-David Rivera Betancour (Carrollian perspective of fluids and holography)
11-Frederick del Pozo (Fractional topology in one-dimensional interacting superconductors)
12-Pauline Besserve (Selected aspects of quantum algorithmics for the quantum many-body problem in the noisy era)
13-Mathieu Beauvillain (Non-linear edge dynamics for quantum-hall droplets)

14h45 - 16h15

14-Mohamed Rekhis (Toroidally-induced Alfven eigenmode (TAE) destabalization by energetic particles in tokamak plasmas)
15-Erik Linner (Multi-channel fluctuating field approach to competing instabilities in interacting electronic systems)
16-Sariah Al Saati (Topological Nodal Ring Semimetal in Graphene)
17-Gabriele Casagrande (Minimal supergravity models for inflation)
18-Anustrup Mukerjee (Search for novel transition metal chalcogenides for thermoelectric applications)
19-Liam Rampon (Exploring strongly correlated condensed matter using numerical methods)
20-Pierre Wang (Triviality of phi-4 theory in the mean field approximation)

Tea Time




James Boust soutiendra publiquement ses travaux de thèse le 18 novembre 2022 au CPHT dans la salle de conférence Louis Michel.

Titre de la thèse : Propriétés magnétiques et optiques de composés de terres rares corrélés à partir des premiers principes 

Membres du Jury :
Alexander Lichtenstein (Universität Hamburg)
Markus Aichhorn (Graz University of Technology)
Silke Biermann (Ecole polytechnique)
Nora Dempsey (Institut Néel CNRS)
Olle Eriksson (Uppsala University)
Cesare Franchini (Universität Wien)

Abstract: In so-called "strongly correlated" materials, the strong Coulomb interaction which correlates the movement of electrons at the atomic scale can give rise to outstanding properties at the macroscopic scale. The materials studied in this thesis contain rare-earth elements (like neodymium) which usually exhibit these strong correlation effects. Due to their remarkable properties, rare-earth compounds have numerous technological applications; they are for instance used as high-performance magnets in electric motors. The demand for rare earths is therefore increasing; on the other hand, mining them is difficult, expensive and polluting. Hence, optimizing the properties and composition of rare-earth-based materials can be of great technological, economical and environmental interest. From the point of view of theoretical physics, describing these materials constitutes a real challenge, precisely due to their strongly correlated nature. In this thesis, we develop theoretical approaches to study the magnetic and optical properties of rare-earth compounds, notably the industrially relevant neodymium magnet. These theoretical methods are said to be from "first principles" as they are based on the fundamental laws governing the physics at the atomic level.



Jan Thorben Schneider soutiendra publiquement ses travaux de thèse le 30 septembre 2022 à 15h00 au CPHT dans la salle de conférence Louis Michel.

Titre de la thèse : Far-from-equilibrium dynamics and entanglement in long-range quantum systems

Directeur de thèse : Laurent Sanchez-Palencia

Membres du jury de thèse

Grégoire Misguich, CEA Saclay, Rapporteur
Marco Schirò, Collège de France, Rapporteur
Karyn Le Hur, École Polytechnique, Examinatrice
Leonardo MazzaUniversité Paris-Saclay, Examinateur
Laurent Sanchez-Palenci, École polytechnique, Directeur de thèse


In this thesis, we study the effects of long-range interactions on out-of-equilibrium and in-equilibrium features of lattice spin models by employing complementary analytical calculations and state-of-the-art tensor-network simulations while particularly focusing on the central and unique quantum feature of entanglement.
First, in the long-range transverse-field Ising model, we show the emergence of a weak form of causality characterised by non-universal dynamical exponents. On the one hand, local magnetisation and correlations have an emergent sub-ballistic causal cone while the marked features in the interior of it propagate super-ballistic or ballistic, respectively. On the other hand, the emergent causal cone for all entanglement entropies is shown to be ballistic irrespective of the interaction range and the interior is without marked features. Second, we determine the equilibrium quantum phase diagram of the long-range XXZ model in terms of the anisotropic coupling and the long-range interaction exponent through studying a representation of the spectrum of the reduced density matrix following a half-chain bipartition, the so-called entanglement spectrum.
We show it exhibits a remarkable self-similarity within the critical phase where the system is described by a Luttinger liquid while the self-similarity extends to the geometric entanglement and the Luttinger parameter.
The transition away from a Luttinger liquid is consistent with the breakdown of self-similarity and a renormalisation group analysis. The synergetic combination of the two latter allows us to locate the corresponding phase transitions which we corroborate by numerical simulations.
Furthermore, we show the entanglement Hamiltonian, the Hermitian operator whose spectrum is the entanglement spectrum, follows the form of the Bisognano--Wichmann theorem in large regions of the phases which include the short-range limit, while such a form can be excluded in the phase where genuinely long-ranged effects are relevant.
Our results shed new light through the lens of quantum entanglement on the out-of-equilibrium as well as ground state features of long-range interacting spin chains and pave the way for further experimental and theoretical studies.