Mardi 8 Septembre 2026, 10:45 à LPTMC, campus Jussieu, couloir 12-13, 5ème étage, salle 5-23	SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée)	cond-mat
Thibault Bertrand ( Imperial College London )	Diffusion in a noisy trap: dynamics and thermodynamics of the OU^2 process
Abstract:	The Ornstein–Uhlenbeck (OU) process is the standard model for confined Langevin dynamics and is used throughout theoretical biology. However, in a number of scenarios including in active cellular environments and optical tweezer experiments, the OU process fails to capture the fluctuating nature of the confining potential itself. To capture these inherently out-of-equilibrium dynamics, we recently introduced the OU2 process, a natural extension where the stiffness of the harmonic trap undergoes its own OU-like fluctuations. In this talk, we explore the dynamics and thermodynamics of this model through a combination of analytical and numerical methods. First, we show that this dynamic probe-controller coupling fundamentally alters the system's dynamics. Unlike the Gaussian decay of the standard OU process, the OU2 probability density exhibits heavy power-law tails. We discuss how these asymptotics qualitatively change the system's trapping behavior, extreme value statistics, and crucially its first passage time (FPT) statistics. Secondly, we analyze the thermodynamic consequences of external driving. When the trap's fluctuations violate detailed balance, we reveal a breakdown of quasistatic (infinite-time) optimality. Instead, continuous work exchange between the probe and controller drives the emergence of finite-time optimal protocols. Ultimately, we hope that the introduction of the OU2 model provides a refined analytical framework for exploring the interplay of anomalous FPT statistics and non-equilibrium control in fluctuating biological systems.

Mardi 8 Septembre 2026, 14:45 à IHES, Amphithéâtre Léon Motchane	PT-IHES (Séminaire de physique théorique de l'IHES)	hep-th
Dam Thanh Son ( University of Chicago & IHES )	Nonrelativistic Conformal Collider Physics of Multiparticle Point Production
Abstract:	Motivated by nuclear experiments where a few neutrons are produced by a local source, we develop a formalism of "nonrelativistic conformal collider physics." We define detector operators in the nonrelativistic conformal field theory describing fermions at unitarity. We reduce the problem of computing the momentum distribution and correlation between final particles produced by a local source ("point-produced") to the computation of correlation functions involving the detector operators. The general formalism is applied to the point production of three unitary fermions, where we find the momentum and angular distribution of final particles, and point production of a large number of fermions. We discuss a nonrelativistic version of celestial holography, which maps the asymptotic out-state to a quantum wave function in the so-called "oscillator frame." Based on arXiv:2608.18202 with Cyuan-Han Chang, Subham Dutta Chowdhury, and Ian Moult.

Mardi 8 Septembre 2026, 16:00 à LPTHE, Bibliothèque du LPTHE, couloir 13-14, salle 401	CONDMAT-THEO (Seminaire commun matiere condensee LPTMC-LPTHE)	cond-mat
Philippe Suchsland ( Google Quantum AI )	Observation of constructive interference at the edge of quantum ergodicity
Abstract:	Quantum observables in the form of few-point correlators are the key to characterizing the dynamics of quantum many-body systems. In dynamics with fast entanglement generation, quantum observables generally become insensitive to the details of the underlying dynamics at long times due to the effects of scrambling. In experimental systems, repeated time-reversal protocols have been successfully implemented to restore sensitivities of quantum observables. Using a 103-qubit superconducting quantum processor, we characterize ergodic dynamics using the second-order out-of-time-order correlators, OTOC(2). In contrast to dynamics without time reversal, OTOC(2) are observed to remain sensitive to the underlying dynamics at long time scales. Furthermore, the OTOC(2) observable is dominated by constructive interference between Pauli strings that form large loops in configuration space. The observed interference mechanism endows OTOC(2) with a high degree of classical simulation complexity, which culminates in a set of large-scale OTOC(2) measurements exceeding the simulation capacity of known classical algorithms. Further supported by an example of Hamiltonian learning through OTOC(2), our results indicate a viable path to practical quantum advantage. (basé sur 2506.10191 )

Jeudi 10 Septembre 2026, 16:00 à DPT-PHYS-ENS, Salle Dussane - 45 rue d'Ulm 75005 PARIS	COLLOQUIUM-ENS (Colloquium of the Physics Department of ENS)	physics
Yury Gogotsi ( Drexel University )	Controlling Physical Properties of MXenes via Synthesis and Surface Chemistry
Abstract:	MXenes are the fastest-growing family of two-dimensional (2D) materials. Unlike most other 2D materials, they lack bulk analogs when restacked because of their surface terminations. They represent a new class of 2D transition-metal carbides/nitrides, not merely exfoliated van der Waals solids. They have a general formula Mn+1XnTx, where M is a transition metal, X is carbon and/or nitrogen, T represents surface terminations (O, OH, halogen, chalcogen, etc.), and n = 2—5. About 50 stoichiometric MXene compositions and dozens of solid solutions on M and X sites have already been reported. Given the infinite number of possible solid-solution compositions and combinations of surface terminations, MXenes offer an opportunity for computationally driven atomistic design of unique inorganic 2D structures. MXenes transformed the way chemists think about 2D materials because their surfaces are chemically active rather than inert. Unlike graphene, MXenes possess tunable surface terminations that can be modified through synthesis and post-treatment. MXenes exhibit electronic, optical, mechanical, and electrochemical properties that clearly distinguish them from other materials. Moreover, these properties are tunable by design and can be modulated using an ionotronic approach, leading to breakthroughs in fields ranging from optoelectronics and communication to electrochemical energy storage, catalysis, sensing, and medicine. Changing surface terminations can dramatically induce superconductivity, alter electrical conductivity, work function, optical properties, and redox activity. In this talk, I’ll discuss methods for MXene synthesis and processing, the effects of MXene chemistry on their physical properties, and provide examples of important applications where MXenes outperform other materials.

Vendredi 11 Septembre 2026, 11:00 à LPENS, E239 (library)	SEM-INFOR (Séminaire informel)	cond-mat.stat-mech
Samuel Garratt	Finite-temperature quantum state complexity from private correlations
Abstract:	Studies of entanglement in the ground states of many-body systems have provided insights into the relation between spatial correlations, low-energy spectral properties, and the computational resources required to describe a system. We know much less about entanglement in thermal equilibrium. In this talk I will discuss constraints on representations of many-body mixed states as statistical ensembles of pure states. First I will derive an entropic inequality that provides a lower bound on the depths of the unitary circuits generating these pure states. This measure of quantum state complexity (which vanishes for separable states with arbitrary classical correlations) is closely related to the private information, a central quantity in quantum cryptography. I will then show how, in thermal states, this notion of complexity is related to linear response. PRL 136 100802/arXiv:2502.13218 & arXiv:2510.02275.

Vendredi 11 Septembre 2026, 13:00 à LPENS, Salle Emile Borel, 29 Ulm	ENS-BIOPHYS (ENS Biophysics Seminar)	physics.bio-ph
Paul Baconnier ( ENS Lyon )	Interaction-Induced Memories Reveal the Complexity of Disordered Matter
Abstract:	Memory effects probe the complexity of disordered matter and its fundamental constituents and interactions. While models based on independent elements capture generic memories, interactions are predicted to produce many new memory effects which so far have been observed in artificial systems only. Here, we reveal that archetypal disordered materials – shape memory alloys, crumpled sheets, and steel wool – store multiple memories that strengthen with repeated cycling, in stark contrast to predictions for non-interacting systems. Interacting-based models capture our observations and predict a cascade of interaction-induced memory motifs, including the dominant one observed here. Moreover, we use these insights to identify and observe additional, subdominant memories. Our results reveal hitherto hidden complexity in disordered media, opening a fresh route towards the observation, modeling and utilization of mechanical memories, including for in- materia computing.

Vendredi 11 Septembre 2026, 14:45 à IHES, Amphithéâtre Léon Motchane	PT-IHES (Séminaire de physique théorique de l'IHES)	hep-th
Andrea Guerrieri ( City St. George's, London University )	TBA

Lundi 14 Septembre 2026, 10:00 à IJCLAB, Building 100 A Auditorium Joliot Curie	SEM-EXCEP (Seminaire exceptionnel)	hep-ph
Ed Copeland ( Nottingham U. )	Searching for cosmic superstrings in Gravitational Waves and the CMB
Abstract:	Talk at the conference “Particle Physics in the Early Universe” https://indico.ijclab.in2p3.fr/event/13541/overview

Lundi 14 Septembre 2026, 10:45 à IJCLAB, Building 100A, Auditiorium Joliot-Curie	SEM-EXCEP (Seminaire exceptionnel)	hep-ph
Juri Smirnov ( Manchester U. )	Dark Matter from a Slightly Broken Mirror
Abstract:	Talk at the conference "Particle Physics in the Early Universe" https://indico.ijclab.in2p3.fr/event/13541/

Lundi 14 Septembre 2026, 11:30 à LPTMC, salle de seminaires du LPTMC (Jussieu, tours 12-13, salle 523)	ATOMES-NCORPS (Seminaire atomes froids et problemes a N corps)	cond-mat
Pascal Naidon ( RIKEN )	Stabilisation of few-body resonances to « bound states in a continuum »
Abstract:	In this talk, I will present how few-body resonances can be stabilised to so-called « bound states in a continuum », i.e. resonances with vanishing width that do not decay. The underlying mechanism can be explained by an effective two-channel description. It shows how the lifetime of few-body resonances can be made infinitely long by a continuous tuning of system parameters. I will illustrate this scenario in two different examples: a mass-imbalanced system in one dimension and a system of three identical bosons in three dimensions, relevant to Efimov physics.

Lundi 14 Septembre 2026, 12:00 à IJCLAB, Auditorium Joliot-Curie, building 100A	SEM-EXCEP (Seminaire exceptionnel)	hep-ph
Oleg Lebedev ( Helsinki U. )	Developments in gravitational particle production
Abstract:	Talk at the conference "Particle Physics in the Early Universe" https://indico.ijclab.in2p3.fr/event/13541/

Lundi 14 Septembre 2026, 14:00 à IJCLAB, Auditorium Joliot-Curie, building 100A	SEM-EXCEP (Seminaire exceptionnel)	hep-ph
Rocky Kolb ( Chicago U. )	Nonthermal leptogenesis via cosmological gravitational particle production
Abstract:	Talk at the conference "Particle Physics in the Early Universe" https://indico.ijclab.in2p3.fr/event/13541/

Lundi 14 Septembre 2026, 14:45 à IJCLAB, Auditorium Joliot-Curie, building 100A	SEM-EXCEP (Seminaire exceptionnel)	hep-ph
Will Kinney ( SUNY Buffalo )	Geodesic Completeness in General Cosmological Scenarios
Abstract:	Talk at the conference "Particle Physics in the Early Universe" https://indico.ijclab.in2p3.fr/event/13541/

Lundi 14 Septembre 2026, 16:00 à IJCLAB, Auditorium Joliot-Curie, building 100A	SEM-EXCEP (Seminaire exceptionnel)	hep-ph
Mikhail Shaposhnikov ( EPFL Lausanne )	Non-compact QCD axion and its gravitational origin
Abstract:	Talk at the conference "Particle Physics in the Early Universe" https://indico.ijclab.in2p3.fr/event/13541/

Lundi 14 Septembre 2026, 16:45 à IJCLAB, Auditorium Joliot-Curie, building 100A	SEM-EXCEP (Seminaire exceptionnel)	hep-ph
Julien Froustey ( IFIC Valencia )	Primordial lepton asymmetries: constraints and consequences
Abstract:	Talk at the conference "Particle Physics in the Early Universe" https://indico.ijclab.in2p3.fr/event/13541/

Mardi 15 Septembre 2026, 10:45 à LPTMC, campus Jussieu, couloir 12-13, 5ème étage, salle 5-23	SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée)	cond-mat
Yann Lanoiselée ( BCAM )	A unifying approach to diffusive transport in annealed heterogeneous media
Abstract:	In this seminar, we will discuss the thermal diffusion in heterogeneous media through the lenses of stochastic processes. Transport as the mesoscopic scale is dominated by thermal fluctuations yielding stochastic motion. While stochastic motion in homogeneous media is understood since Einstein and his derivation of Brownian motion, its extension to heterogeneous media remains to elucidate. Heterogeneity induces induce statistical deviations from Brownian motion as will be discussed in the context of diffusion in living cells. The two main effects are anomalous diffusion where the mean squared displacement displays a power-law scaling and non-Gaussian displacement statistics which may occur at the same time. We will discuss how anomalous and non-Gaussian diffusion articulate. To do so, we introduce the concept of Randomly Modulated Gaussian Processes [1] as a unifying framework for modelling, analysing and classifying diffusion in heterogeneous media. This formulation incorporates correlations in the displacements together with correlated fluctuations of their amplitudes. Most known models of anomalous diffusion (including Continuous-Time Random Walk, fractional Brownian motion but also Lévy flights) and random diffusivity can be described and generalized within this framework. Moreover, the unified view identifies the main statistical properties to be probed experimentally for a reliable classification of diffusive dynamics. [1] A unifying approach to diffusive transport in annealed heterogeneous media. Y. Lanoiselée, D. S. Grebenkov, G. Pagnini, arXiv:2603.12775 (2026) (basé sur 2603.12775 )

Mardi 15 Septembre 2026, 14:00 à LPTHE, library	LPTHE-PPH (Particle Physics at LPTHE)	hep-ph
Manqi Ruan ( IHEP, Beijing )	Learning from all hits/particles -- Machine Learning at collider and cosmic-ray frontier
Abstract:	The machine learning technologies could efficiently extract information from data, and significantly boost the performance and discovery power of large science facilities. Using ParticleNet or ParticleTransformer, we observe 3-4 folds improvements on benchmark physics measurements at collider frontier -- including both LEP legacy experimental data and simulated study for future Higgs factories. Apply the similar methodology to the cosmic-ray experiment of LHAASO, the significance of standard candle -- crab nebula -- could be improved by 50% to 3 times. We also observe significant scaling behavior that describes the emerge and saturation of performance, which could be used to diagnosis the AI behavior and to quantify/control the effect of data-MC discrepancy.

Mardi 22 Septembre 2026, 10:45 à LPTMC, campus Jussieu, couloir 12-13, 5ème étage, salle 5-23	SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée)	cond-mat
Florian Simon ( TUM )	Quantum geometry: a white cane for unconventional and topological superconductivity ?
Abstract:	In this talk, I will present a recent preprint on the quantum geometry of superconductors [1]. I will begin by introducing quantum geometry as a general consequence of the U(1) gauge invariance of quantum mechanics, leading to different incarnations throughout physics (and beyond). I will then discuss the specific example of quantum geometry in the band theory of crystals, along with its physical interpretations. I will then summarize my PhD research, where I studied the influence of the normal state quantum geometry on the superconducting phase. From this discussion, I will then motivate the study of the quantum geometry of the superconducting state itself, notably regarding the limitations of classification schemes in topological superconductivity and experimental studies of unconventional superconductivity. I will then present the results of Ref. [1], where we determine sufficient conditions for the quantum geometry of the superconducting phase To exactly separate into a normal-state contribution and a "pairing" quantum geometry, driven by superconductivity. We then determine explicit expressions for the pairing quantum geometry of all pairings, including non-unitary triplet pairings. These results will hopefully serve as a foundation for geometry-based design rules for superconductors, and contribute to the experimental exploration of unconventional superconductivity. [1] F. Simon, T. Bernat & A.M. Black-Schaffer, Composite quantum geometry of superconductors (2026). Arxiv. doi:10.48550/arXiv.2608.02434

Mardi 22 Septembre 2026, 15:30 à LPENS, Conf IV	COURS (Cours)	cond-mat.stat-mech
Zhijin Li ( Southeast U., Nanjing )	TBA

Jeudi 24 Septembre 2026, 11:00 à IHES, Amphithéâtre Léon Motchane ( Séminaire de Géométrie Arithmétique )	MATH-IHES (TBA)	math
Weizhe Zheng ( Morningside Center of Mathematics, Chinese Academy of Sciences & IHES )	Hodge-Riemann Relations for Vector Bundles
Abstract:	The hard Lefschetz theorem and Hodge-Riemann relations are fundamental results on the cohomology of Kähler manifolds and have found important applications in combinatorics. In this talk, we will explore extensions of Hodge-Riemann relations to certain vector bundles and applications to log-concavity.

Jeudi 24 Septembre 2026, 14:30 à IHES, Amphithéâtre Léon Motchane	PT-IHES (Séminaire de physique théorique de l'IHES)	hep-th
Andrea Antinucci ( Oxford University & IHES )	Proliferation Transitions for Non-Abelian Anyons
Abstract:	Phases of matter and the transitions between them are famously characterized within the Landau paradigm and Landau-Ginzburg theory: phases are labeled by broken or unbroken symmetries, while phase transitions are described in terms of scalar order parameters. There are, however, phases beyond the standard Landau paradigm that are distinguished not by the realization of ordinary symmetries, but by that of generalized global symmetries. Among these, topologically ordered phases in $(2+1)d$ possess non-invertible 1-form symmetries described by anyon lines. In this talk, I will present a framework for describing transitions between topologically ordered phases related by anyon proliferation, which can be viewed as a non-invertible generalization of the choice of the unbroken symmetry. The resulting theories involve scalar fields coupled to gauge fields. A crucial ingredient in this construction is the $(3+1)d$ Symmetry Topological Field Theory (SymTFT), which allows to separate symmetry from dynamics and will be employed in a rather unconventional way.

Vendredi 25 Septembre 2026, 13:00 à LPENS, TBA	ENS-BIOPHYS (ENS Biophysics Seminar)	physics.bio-ph
Stephanie Palmer ( University of Chicago )	TBA

Mardi 29 Septembre 2026, 10:45 à LPTMC, campus Jussieu, couloir 12-13, 5ème étage, salle 5-23	SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée)	cond-mat
Mike Chatzittofi ( DAMTP )	TBA

Mardi 29 Septembre 2026, 14:00 à LPENS, Conf IV	COURS (Cours)	cond-mat.stat-mech
Zhijin Li ( Southeast U., Nanjing )	TBA

Mardi 29 Septembre 2026, 14:00 à LPTHE, library	LPTHE-PPH (Particle Physics at LPTHE)	hep-ph
Ajjath Abdul-Hameed ( Indian Institute of Science, Bengaluru )	TBA

Jeudi 1 Octobre 2026, 11:30 à IHP, Yvette Cauchois or Darboux	RENC-THEO (Rencontres Théoriciennes)	hep-th
Andrei Parnachev ( Trinity College, Dublin )	TBA
Abstract:	TBA

Vendredi 2 Octobre 2026, 13:00 à LPENS, Emile Borel, 29 Ulm	ENS-BIOPHYS (ENS Biophysics Seminar)	physics.bio-ph
Mathias Heltberg ( Niels Bohr Institute )	TBA
Abstract:	TBA

Mardi 6 Octobre 2026, 14:45 à IHES, Amphithéâtre Léon Motchane	PT-IHES (Séminaire de physique théorique de l'IHES)	hep-th
Bernardo Zan ( Università di Genova )	On the Wilson-Fisher Fixed Point in the Limit of Integer Spacetime Dimensions
Abstract:	TBA

Jeudi 8 Octobre 2026, 11:00 à LPTHE, bibliothèque du LPTHE, tour 13-14, 4eme étage	SEM-DARBOUX (Séminaire Darboux - physique théorique et mathématiques)	hep-th
Veronica Fantini ( Laboratoire de Mathématiques d'Orsay )	TBA

Vendredi 9 Octobre 2026, 13:00 à LPENS, Salle Camille Marbo, 29 ULM	ENS-BIOPHYS (ENS Biophysics Seminar)	physics.bio-ph
Maria Martinez Rodriguez ( Yale University )	TBA
Abstract:	TBA