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Tuesday 11 February 2020, 11:00 at CPHT, Salle Louis Michel SEM-CPHT (Séminaire du CPHT) hep-th
Keun-Young Kim ( GIST ) TBA

Wednesday 12 February 2020, 14:15 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-MAT (Séminaire de matrices, cordes et géométries aléatoires) hep-th
Evgeny Skvortsov Quantum Higher Spin Gravity and three-dimensional bosonization duality
Abstract: Higher Spin Gravities are supposed to be minimalistic extensions of gravity that embed it into a quantum consistent theory. However, such minimality turns out to be in tension with the field theory approach, as well as with the numerous no-go theorems. We report on the recent progress in constructing Higher Spin Gravities and testing quantum effects therein. The same time, via AdS/CFT Higher Spin Gravities should be related to a variety of interesting three-dimensional CFT

Tuesday 18 February 2020, 11:00 at CPHT, Salle Louis Michel, CPHT, Ecole Polytechnique SEM-CPHT (Séminaire du CPHT) hep-th
Blagoje Oblak ( LPTHE ) Virasoro Berry Phases in the KdV Equation
Abstract: I consider a model of fluid particle motion given by the reconstructed KdV equation on a circle. For travelling waves that are "uniformizable" in a suitable sense, the map that governs stroboscopic motion can be derived analytically. The particle's drift velocity, then, is essentially the Poincaré rotation number of that map, and has a geometric origin: it is the sum of a dynamical phase, a geometric/Berry phase, and an "anomalous phase". The last two phases are universal, as they follow entirely from the underlying Virasoro group structure. The Berry phase, in particular, is produced by a sequence of adiabatic conformal transformations due to the moving wave profile, and was previously found in two-dimensional conformal field theories.

Tuesday 18 February 2020, 17:15 at DPT-PHYS-ENS, Amphi Jaurès - Département de Physique de l'ENS 24 rue Lhomond 75005 PARIS COLLOQUIUM-ENS (Colloquium of the Physics Department of ENS) physics
Frédéric Restagno ( Laboratoire de Physique des Solides, CNRS, Université Paris-Saclay ) Slip of polymer fluids
Abstract: Modeling fluid flows in channels is a general problem in science and engineering. For ideal liquids, the situation is simple: there is no dissipation due to fluid movement. For real liquids, some energy is lost. Navier, in his pioneering work on fluid mechanics identified two possible sources of dissipation: bulk dissipation, associated to the viscosity and the friction of the last layer of liquid molecules sliding on the solid surface. For surface dissipation, a classical assumption of fluid dynamics is that a liquid element adjacent to the surface is equal to the velocity of the surface, i.e. a non-slip boundary condition, which leads to no surface dissipation. This is not the only possibility. Navier, postulating the existence of a slip velocity at the surface, introduced the possibility of surface dissipation. He proposed a linear relation between the shear stress at the solid-liquid interface and the slip velocity: σ=kV, where k is the interfacial friction coefficient. Indeed, it is also possible to define the slip length b as the distance from the solid surface where the fluid velocity profile extrapolates linearly to zero. During this presentation, I will briefly review what we know on the boundary condition for simple Newtonian liquids and show that polymers, due to their entanglements present a unique tool to study and understand the Navier condition. Based on a setup using the photobleaching of fluorescent polymers, I will present our last results on the slip of polymer melts and polymer solutions.

Wednesday 19 February 2020, 14:15 at IPHT, Salle Claude Itzykson, Bât. 774 IPHT-MAT (Séminaire de matrices, cordes et géométries aléatoires) hep-th
Geoffrey Compère ( Université Libre de Bruxelles ) Some physics behind supertranslations and superrotations
Abstract: I will first provide a bird-eye view upon the infrared structure of gravity. I will shortly describe the relationship between BMS symmetry, soft theorems and memory effects at leading and subleading orders in the large radius expansion, while emphasizing the specificities of super-Lorentz symmetries. Secondly, I will present a no-go result on the soft hair conjecture: supertranslations induced by matter creating and falling inside black holes do not affect Hawking radiation, though they do affect scattering amplitudes. I will start by proving that Unruh radiation is unaffected by supertranslations induced by a shockwave and then show that Hawking radiation is mathematically related to this system, as a consequence of the principle of equivalence. Third, I will explain how BMS symmetry is associated to flux-balance laws that provide constraints upon the motion of binary compact mergers. Finally, I will present the extension of the BMS group to asymptotically de Sitter spacetimes.

Monday 24 February 2020, 10:30 at LPTMC, Jussieu tower 13-12 5th floor room 5-23
( Mini-lecture: three times 1.5 hours )
SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée) cond-mat.mes-hall
Janos Asboth ( Wigner Research Centre for Physics, Budapest, Hongrie ) Kitaev's toric code and its use in quantum computation (part 1)
Abstract: TBA

Tuesday 25 February 2020, 10:30 at IHES, Amphithéâtre Léon Motchane
( Cours de l'IHES )
MATH-IHES (TBA) hep-th
Bruno Klingler ( Humboldt Universität, Berlin ) Tame Geometry and Hodge Theory (1/4)
Abstract: Hodge theory, as developed by Deligne and Griffiths, is the main tool for analyzing the geometry and arithmetic of complex algebraic varieties. It is an essential fact that at heart, Hodge theory is NOT algebraic. On the other hand, according to both the Hodge conjecture and the Grothendieck period conjecture, this transcendence is severely constrained. Tame geometry, whose idea was introduced by Grothendieck in the 80s, seems a natural setting for understanding these constraints. Tame geometry, developed by model theorists as o-minimal geometry, has for prototype real semi-algebraic geometry, but is much richer. It studies structures where every definable set has a finite geometric complexity. The aim of this course is to present a number of recent applications of tame geometry to several problems related to Hodge theory and periods. After recalling basics on o-minimal structures and their tameness properties, I will discuss: - the use of tame geometry in proving algebraization results (Pila-Wilkie theorem; o-minimal Chow and GAGA theorems in definable complex analytic geometry); - the tameness of period maps; algebraicity of images of period maps; - functional transcendence results: Ax-Schanuel conjecture from abelian varieties to Shimura varieties and variations of Hodge structures. Applications to atypical intersections (André-Oort conjecture and Zilber-Pink conjecture); - the geometry of Hodge loci and their closures.

Wednesday 26 February 2020, 10:30 at IHES, Amphithéâtre Léon Motchane
( Cours de l'IHES )
MATH-IHES (TBA) hep-th
Bruno Klingler ( Humboldt Universität, Berlin ) Tame Geometry and Hodge Theory (2/4)
Abstract: Hodge theory, as developed by Deligne and Griffiths, is the main tool for analyzing the geometry and arithmetic of complex algebraic varieties. It is an essential fact that at heart, Hodge theory is NOT algebraic. On the other hand, according to both the Hodge conjecture and the Grothendieck period conjecture, this transcendence is severely constrained. Tame geometry, whose idea was introduced by Grothendieck in the 80s, seems a natural setting for understanding these constraints. Tame geometry, developed by model theorists as o-minimal geometry, has for prototype real semi-algebraic geometry, but is much richer. It studies structures where every definable set has a finite geometric complexity. The aim of this course is to present a number of recent applications of tame geometry to several problems related to Hodge theory and periods. After recalling basics on o-minimal structures and their tameness properties, I will discuss: - the use of tame geometry in proving algebraization results (Pila-Wilkie theorem; o-minimal Chow and GAGA theorems in definable complex analytic geometry); - the tameness of period maps; algebraicity of images of period maps; - functional transcendence results: Ax-Schanuel conjecture from abelian varieties to Shimura varieties and variations of Hodge structures. Applications to atypical intersections (André-Oort conjecture and Zilber-Pink conjecture); - the geometry of Hodge loci and their closures.

Wednesday 26 February 2020, 12:00 at LPENS, Conf. IV FORUM-ENS (Forum de Physique Statistique @ ENS) cond-mat.stat-mech
Massimo Vergassola ( ENS Paris ) TBA

Thursday 27 February 2020, 10:00 at IHP, 314 RENC-THEO (Rencontres Théoriciennes) hep-th
Jay Armas ( University of Amsterdam ) TBA
Abstract: TBA

Thursday 27 February 2020, 13:30 at LPTMC, Jussieu tower 13-12 5th floor room 5-23
( Mini-lecture: three times 1.5 hours )
SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée) cond-mat.mes-hall
Janos Asboth ( Wigner Research Centre for Physics, Budapest (Hongrie) ) Kitaev's toric code and its use in quantum computation (part 2)
Abstract: TBA

Monday 2 March 2020, 11:00 at LPTMC, Jussieu tower 13-12 5th floor room 5-23 SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée) cond-mat.mes-hall
Matthieu Tissier ( LPTMC ) TBA
Abstract: TBA

Monday 2 March 2020, 11:30 at LPTENS, Scherk library (formerly LPTENS library) STR-LPT-ENS-HE (Séminaire commun LPTENS/LPTHE) hep-th
Yashar Akrami ( LPENS ) TBA

Monday 2 March 2020, 13:30 at LPENS, Conf IV LPENS-MDQ (Séminaire Matériaux et Dispositifs Quantiques du LPENS) cond-mat
Gian Lorenzo Paravicini-Bagliani ( ETH Zürich and University of Strasbourg ) Magneto-transport in 2DEG ultra-strongly coupled to a Cavities Vacuum-Field
Abstract: According to quantum mechanics, an electromagnetic mode without real photon excitations is non-trivial. It gives rise to vacuum electric field fluctuations. Despite averaging to zero over time, these fluctuations are responsible for the spontaneous emission, the Lamb shift and the Casimir effect. Using Landau polaritons, we demonstrate experimentally that the vacuum electric field acts on electron transport. The DC magneto- resistance of the cavity-embedded 2D electron gas is changed due to the coupling to vacuum. Intriguingly, our experimental platform allows to tune the vacuum mode in-situ, while observing the response in the resistance.

Tuesday 3 March 2020, 10:30 at IHES, Amphithéâtre Léon Motchane
( Cours de l'IHES )
MATH-IHES (TBA) hep-th
Bruno Klingler ( Humboldt Universität, Berlin ) Tame Geometry and Hodge Theory (3/4)
Abstract: Hodge theory, as developed by Deligne and Griffiths, is the main tool for analyzing the geometry and arithmetic of complex algebraic varieties. It is an essential fact that at heart, Hodge theory is NOT algebraic. On the other hand, according to both the Hodge conjecture and the Grothendieck period conjecture, this transcendence is severely constrained. Tame geometry, whose idea was introduced by Grothendieck in the 80s, seems a natural setting for understanding these constraints. Tame geometry, developed by model theorists as o-minimal geometry, has for prototype real semi-algebraic geometry, but is much richer. It studies structures where every definable set has a finite geometric complexity. The aim of this course is to present a number of recent applications of tame geometry to several problems related to Hodge theory and periods. After recalling basics on o-minimal structures and their tameness properties, I will discuss: - the use of tame geometry in proving algebraization results (Pila-Wilkie theorem; o-minimal Chow and GAGA theorems in definable complex analytic geometry); - the tameness of period maps; algebraicity of images of period maps; - functional transcendence results: Ax-Schanuel conjecture from abelian varieties to Shimura varieties and variations of Hodge structures. Applications to atypical intersections (André-Oort conjecture and Zilber-Pink conjecture); - the geometry of Hodge loci and their closures.

Tuesday 3 March 2020, 11:00 at CPHT, Salle Louis Michel SEM-CPHT (Séminaire du CPHT) hep-th
Giuseppe Policastro ( ENS ) TBA
Abstract: TBA

Tuesday 3 March 2020, 17:15 at DPT-PHYS-ENS, Conf IV (E244) - Département de Physique de l'ENS 24 rue Lhomond 75005 PARIS COLLOQUIUM-ENS (Colloquium of the Physics Department of ENS) physics
Matteo Barsuglia ( Laboratoire Astroparticules et Cosmologie (APC), Université de Paris ) The Einstein Telescope project and the future of the earth-based gravitational-wave astronomy
Abstract: Gravitational astronomy, which began on September 14th, 2015 with the LIGO detection of the merger of two black holes, has demonnstrated all its scientific potential during the 01 (LIGO) and 02 (LIGO-Virgo) observation periods, between 2015 and 2017. At present, LIGO and Virgo are carrying out a third observation run, started on April 1st 2019, with the detection of a few gravitational-wave candidates per month. A program of detector upgrades, alternated with observation runs, will continue for most of the 2020 decade. After that period, a radical change of the detector infrastructure is necessary. The Einstein Telescope Europan project aims to continue the scientific program of Virgo and LIGO, with a detector having tenfold greater sensitivity than current instruments, 10 km arms, and an underground infrastructure. In this presentation, I will begin by introducing the scientific motivations for Einstein Telescope, then I will describe the planned technology and the implementation plans for the detector.

Wednesday 4 March 2020, 10:30 at IHES, Amphithéâtre Léon Motchane
( Cours de l'IHES )
MATH-IHES (TBA) hep-th
Bruno Klingler ( Humboldt Universität, Berlin ) Tame Geometry and Hodge Theory (4/4)
Abstract: Hodge theory, as developed by Deligne and Griffiths, is the main tool for analyzing the geometry and arithmetic of complex algebraic varieties. It is an essential fact that at heart, Hodge theory is NOT algebraic. On the other hand, according to both the Hodge conjecture and the Grothendieck period conjecture, this transcendence is severely constrained. Tame geometry, whose idea was introduced by Grothendieck in the 80s, seems a natural setting for understanding these constraints. Tame geometry, developed by model theorists as o-minimal geometry, has for prototype real semi-algebraic geometry, but is much richer. It studies structures where every definable set has a finite geometric complexity. The aim of this course is to present a number of recent applications of tame geometry to several problems related to Hodge theory and periods. After recalling basics on o-minimal structures and their tameness properties, I will discuss: - the use of tame geometry in proving algebraization results (Pila-Wilkie theorem; o-minimal Chow and GAGA theorems in definable complex analytic geometry); - the tameness of period maps; algebraicity of images of period maps; - functional transcendence results: Ax-Schanuel conjecture from abelian varieties to Shimura varieties and variations of Hodge structures. Applications to atypical intersections (André-Oort conjecture and Zilber-Pink conjecture); - the geometry of Hodge loci and their closures.

Thursday 5 March 2020, 11:00 at LPTHE, bibliothèque du LPTHE, tour 13-14, 4eme étage SEM-DARBOUX (Séminaire Darboux - physique théorique et mathématiques) math.AG
Emanuele Macri ( Northeastern University ) Bridgeland stability on threefolds
Abstract: The theory of Bridgeland stability conditions has seen important developments in the past few years. Emerging from the mathematical physics literature, in particular in Douglas' work, it now connects to different branches in mathematics including symplectic geometry and representation theory. In this talk we will give a quick introduction to the basic theory of stability conditions for the derived category of coherent sheaves on a smooth projective variety, focusing on the recent advances in the threefold case; in particular, on the existence result for the quintic Calabi-Yau threefold.

Thursday 5 March 2020, 13:30 at LPTMC, Jussieu tower 13-12 5th floor room 5-23
( Mini-lecture: three times 1.5 hours )
SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée) cond-mat.mes-hall
Janos Asboth ( Wigner Research Centre for Physics, Budapest, Hongrie ) Kitaev's trois code and its use in quantum computation (part 3)

Friday 6 March 2020, 11:00 at APC, Amphithéatre Pierre Gilles de Gennes APC-COLLOQUIUM (Colloquium de l'APC) astro-ph
Valeria Petorino TBA

Tuesday 10 March 2020, 11:00 at IHP, Salle 314 P^3 (Particle Physics in Paris) hep-ph|hep-th
Andrea Wulzer ( CERN and EPFL ) TBA

Wednesday 11 March 2020, 12:00 at LPENS, Conf. IV FORUM-ENS (Forum de Physique Statistique @ ENS) cond-mat.soft
Jacopo De Nardis ( Ghent University ) TBA

Wednesday 11 March 2020, 13:45 at LKB, ENS - Dept Phys - Conf IV - 24, rue Lhomond - 75005 Paris SEM-LKB (Séminaire du Laboratoire Kastler Brossel) quant-ph
Atac Imamoglu ( ETH Zurich ) Polariton-electron interactions in van der Waals heterostructures
Abstract: Two dimensional materials provide new avenues for synthesizing compound quantum systems. Monolayers with vastly different electric, magnetic or optical properties can be combined in van der Waals heterostructures which ensure the emergence of new functionalities; arguably, the most spectacular example to date is the observation of strong correlations and low electron density superconductivity in moire superlattices obtained by stacking two monolayers with a finite twist angle. Optically active monolayers such as molybdenum diselenide provide a different "twist" as they allow for investigation of nonequilibrium dynamics in van der Waals heterostructures by means of femtosecond pump-probe measurements. Moreover, interactions between electrons and the elementary optical excitations such as excitons or polaritons, provide an ideal platform for investigation of quantum impurity physics, with possibilities to probe both Fermi- and Bose-polaron physics as well as mixtures with tunable density of degenerate fermions and bosons. After introducing the framework we use to describe many-body optical excitations in van der Waals heterostructures, I will describe two recent developments in the field. The first experiment uses pump-probe measurements to demonstrate how exciton-electron interactions lead to strong enhancement of polariton-polariton interactions, as well as to optical gain by stimulated cooling of exciton-polaron-polaritons. The second experiment shows that a tri- layer system, consisting of two semiconducting monolayers separated by an insulating layer, provides an exciting platform for investigating strongly correlated electronic states in moire superlattices using optical spectroscopy.

Thursday 12 March 2020, 10:00 at IHP, 314 RENC-THEO (Rencontres Théoriciennes) hep-th
Francesco Benini ( SISSA, Trieste ) TBA

Friday 13 March 2020, 11:00 at APC, Amphithéatre Pierre Gilles de Gennes APC-COLLOQUIUM (Colloquium de l'APC) astro-ph
Francoise Combes TBA

Friday 13 March 2020, 14:00 at LPTHE, library LPTHE-PPH (Particle Physics at LPTHE) hep-ph
Andrea Wulzer ( Padova U. ) TBA

Monday 16 March 2020, 13:30 at LPENS, Conf IV LPENS-MDQ (Séminaire Matériaux et Dispositifs Quantiques du LPENS) cond-mat
Nicolas Roch ( Institut Néel, Grenoble ) TBA
Abstract: TBA

Tuesday 17 March 2020, 11:00 at LPTHE, LPTHE library STR-LPT-ENS-HE (Séminaire commun LPTENS/LPTHE) hep-th
Chrysoula Markou ( Munich (Max Planck Institute) ) Bimetric theory, supersymmetry and string theory

Tuesday 17 March 2020, 11:00 at IPHT, Salle Claude Itzykson, Bât. 774 SEM-EXCEP (Séminaire exceptionel) physics
Nicolas Sangouard Calcul et cryptographie quantiques
Abstract: (TBA)

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