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 :
CPHT 
Ecole Polytechnique 
91128 Palaiseau cedex 
France

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

Write an email to someone at CPHT :  : firstname.lastname@polytechnique.edu

 

L’aménagement du patio avance bien. Nous avons déjà notre petit verger (pommiers, poiriers, figuier…), et surtout de la terre qui est préparée pour les plantations, nous avons 5 parcelles prêtes à l’emploi qui n’attendent que nous !

Vendredi 21 avril à 13h15  réunion mensuelle dans le patio

C’est une réunion très importante car nous devons décider :

- Qu’est-ce que nous allons planter ? (tomates ? concombres ? pommes de terres ? herbes aromatiques ? herbes médicinales ? etc)

- Comment nous allons planter sur 5 parcelles ? Parcelles thématiques (ex. : légumes ; herbes …) ? Parcelles par famille botanique (ex : Cucurbitacées …) ? Autre ?

- Quand allons-nous planter ? Nous devons établir un planning de plantation. Les jardiniers nous conseillent vivement de planter très rapidement, c’est-à-dire la semaine prochaine, tant que la terre n’est pas encore très dure.

- Combien nous sommes pour planter ?

Venez nombreux avec vos idées ! Parlez-en autour de vous avec vos collègues !

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Le 29 juin 2023 aura lieu à l'ENS-Lyon la sixième  Journée Parité 2023 organisée par Olga Paris-Romaskevich, Frédérique Bienvenüe, Vincent Borrelli, Jean-René Chazottes, Claire Lacour, Bertrand Rémy.

Cette 6ème Journée Parité s'adresse à celles et ceux intéressé·e·s qui veulent réfléchir et échanger sur les manières d'agir pour une communauté mathématique inclusive, apaisée et ouverte. Nous espérons qu'elle vous apportera du soutien, des outils, des idées et de belles rencontres pour encore plus de sens dans cette aventure collective.

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The 12th CPHT Young Researchers Seminar will be held on April 19, 2023 at 3:00 p.m. in the Louis Michel Conference Room with two presentations :

Simon Pekar (Université de Mons) : Higher-spin gravity in flat space: old results and new developments
Arnaud Delfante (Université de Mons) : Weyl-Fefferman-Graham gauge and asymptotic symmetries

The seminar will be followed by a high tea.

English

 

The 11th CPHT Young Researchers Seminar will be held on April 14, 2023 at 3:00 p.m. in the Louis Michel Conference Room with two presentations :

Mikel Sanchez Garitaonandia (CPHT, CNRS, École Polytechnique) : Gravitational Waves from First Order Phase Transitions

Jong-Hyun Yoon (IJCLab, CNRS/IN2P3, Université Paris-Saclay) : Inflationary Big Bang Cosmology and Dark Matter

The seminar will be followed by a high tea.

English

 

Tuesday, April 4 at 14:00

Conference room Louis Michel (CPHT)

Erik Linnér (CPHT, École Polytechnique)

A theoretical description of the interplay of collective fluctuations in strongly correlates systems

Abstract: Correlated fermion systems often display complex phase diagrams with different competing orderings. A theoretical description of competing instabilities remains one of the major challenges of modern condensed matter physics. We introduce a multi-channel extension of the recently developed fluctuating field approach to tackle this problem, based on a variational optimization of a trial action that explicitly contains the leading fluctuation channels [1]. Application of the approach to extended Hubbard models captures the interplay of competing charge density wave, antiferromagnetic, s-wave superconductivity, and phase separation fluctuations [1,2]. For the case of the attractive model, our approach has allowed us to identify a novel phase that is characterised by the coexistence of s-wave superconductivity and phase separation [2]. Our findings resonate with previous observations of interplaying phase separation and superconducting phases in electronic systems, most importantly in high-temperature superconductors.

[1] E. Linnér, A. I. Lichtenstein, S. Biermann, E. A. Stepanov, Multi-channel fluctuating field approach to competing instabilities in interacting electronic systems, arXiv:2210.05540 (2022).

[2] E. Linnér, C. Dutreix, S. Biermann, E. A. Stepanov, Coexistence of s-wave superconductivity and phase separation in the half-filled extended Hubbard model with attractive interactions, arXiv:2301.10755 (2023).

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Tuesday, March 21 at 14:00

Conference room Laurent Schwartz (CMLS)

Dario Fiore Mosca (CPHT)

Multipolar magnetism in 5d osmate double perovskites

Abstract: The Spin-Orbit Coupling effect plays a crucial role in the correlated electron physics of 5d transition metal oxides, enabling the formation of unique magnetic phases involving high-rank magnetic multipoles. We show that the 5d1 osmate double perovskite Ba2NaOsO6 and 5d2 Ba2MOsO6 (M = Mg, Ca, Zn) are ideal for exploring such physics. They display strong interconnection between the structural, electronic, and magnetic degrees of freedom that gives rise to multipolar interactions, multipolar order, and spin-orbit polarons.

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Tuesday, March 14 at 14:00

at CPHT, Conference room Louis Michel

Mihailo Cubrovic (University of Belgrade)

Holography for strange metals from A to B

Abstract: I will discuss selected applications of the holographic duality (AdS/CFT, gauge/gravity duality) in strongly correlated systems, in particular the description of strange metals. After introducing the basic notions of holography on an informal level, I will consider the holographic scaling atlas, semilocal quantum liquids and attempts to describe a strongly coupled holographic Fermi liquid. Toward the end holographic lattices and (if time permits) some relations to quantum chaos will be discussed. The talk is mainly a broad review of holographic strange metals but also includes some recent original results.

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The 9th CPHT Young Researchers Seminar will be held on February 24, 2023 at 3:00 p.m. in the Louis Michel Conference Room with two presentations given by :

Pierre Wang (CPHT, CNRS, École Polytechnique) : Triviality of the \varsigma^4_4-theory using the flow equations in the mean-field approximation

Saeed Sadeghi Arjmand (CMLS, CNRS, École Polytechnique) : Minimal-time and potential mean field games with state constraints

The seminar will be followed by a high tea.

English

 

Tuesday, February 21 at 14:00 at CPHT,

Conference room Louis Michel

Irenée Frerot (Institute Néel, CNRS, Grenoble)

Bell's inequalities for many-body systems

Abstract : The violation of Bell's inequalities (BI) is a fundamental manifestation of quantum entanglement. Over the recent years, its was progressively recognized that BI allow one to probe fine features of quantum entanglement in many-body systems from minimal assumptions regarding the details of the experimental implementation. I will present the conceptual framework to investigate BI in multipartite systems, as well as the computational challenges associated to the construction of relevant many-body BI. I will present recently-developed approaches, inspired by so-called inverse problems of statistical physics, to overcome this challenge. I will discuss new BI tailored to specific families of quantum many-body states, such as spin-squeezed or spin singlet states. I will conclude by mentioning the self-testing phenomenon, in which the maximal violation of tailored BI allow one to make strong statements on the structure of the prepared quantum state and measurements from minimal assumptions, in a many-body context. Although still delicate for both theory and experiments, the concept of self-testing might become in the future an important tool for the certification of quantum computation devices.

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