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Upcoming Seminars [Next 30 ]
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Monday 5 December 2022, 15:00 at LPTHE, LPTHE LIbrary SEM-LPTHE (Séminaire du LPTHE) cond-mat
Marco Schirò ( IPhT and Collège de France ) Unravelling Quantum Many Body Dynamics
Abstract: Quantum statistical mechanics and condensed matter physics traditionally deal with the collective behaviour of systems in thermal equilibrium. Here remarkable phenomena are known to emerge at low energy, as a result of strong interactions and quantum statistics. Whether genuine quantum effects can survive far away from thermal equilibrium is a question which has recently attracted broad interest and found several theoretical and experimental motivations. In this talk I will review the recent progress in understanding the dynamics of strongly interacting quantum systems far from equilibrium. Along the way I will discuss the paradox of quantum thermalisation and its breakdown due to quenched disorder or quantum measurements.

Tuesday 6 December 2022, 11:00 at LPTMS, Salle des séminaires du FAST et du LPTMS, bâtiment Pascal n°530
( Hybrid: onsite seminar + zoom. For zoom info, please write to valentina.ros@universite-paris-saclay.fr or check LPTMS website http://lptms.u-psud.fr/en/ )
LPTMS (Séminaire du Laboratoire de Physique Théorique et Modèles Statistiques (Orsay)) cond-mat.stat-mech
Elisabeth Agoritsas ( EPFL and University of Geneva ) Towards a unifying (mean-field) picture of driven disordered systems
Abstract: Disorder is ubiquitous in physical systems, and can radically alter their physical properties compared to their ‘pure’ counterparts. For instance, amorphous materials such as emulsions, foams, metallic glasses or biological tissues are all structurally disordered, and this has key implications for their rheological, mechanical or transport properties. Nevertheless, theoretical descriptions of such ‘driven’ amorphous materials remain challenging, despite decades of extensive analytical and computational studies. The difficulties pertain to the interplay of competing sources of stochasticity, and to the resulting out-of-equilibrium nature of these systems. A standard model for amorphous materials, which allows one to focus on the key role of their structural (positional) disorder, is provided by dense many-body systems of pairwise interacting particles. Here I will introduce an exact Dynamical Mean-Field Theory (DMFT) for these many-body systems, derived in the limit of infinite spatial dimension. In this framework, the many-body Langevin dynamics of the whole problem can be exactly reduced to a single scalar effective stochastic process, and dynamical observables such as pressure or shear stress can be computed for arbitrary driving protocols. Using this DMFT, we were in particular able to establish a direct equivalence between a global forcing (external shear) and a random local forcing (reminiscent of active matter), upon a simple rescaling of the control parameter (the accumulated strain). In this framework, global shear is thus simply a special case of a much broader family of local forcing that can be explored by tuning its spatial correlations. Our predictions were moreover found to be in remarkably good agreement with two-dimensional numerical simulations. These results hint at a unifying framework for establishing rigorous analogies, at the mean-field level, between different families of driven disordered systems, such as sheared granular materials and active matter, or machine-learning algorithms.

Tuesday 6 December 2022, 14:00 at LPENS, E239 LPTENS-HE (Séminaire commun LPTENS-LPTHE) hep-th
Avik Banerjee ( ENS Paris ) Horizon Cap beyond equilibrium
Abstract: Computing real-time Schwinger-Keldysh (SK) correlation functions away from equilibrium stands out to be a theoretically outstanding as well as phenomenologically relevant problem in the holographic approach to the strongly interacting many-body systems. However, the realization of the bulk analogue of the SK contour away from equilibrium has remained elusive within the holographic framework for a long time. Lately, a promising (Horizon crosscap) prescription in this context has been put forward by Crossley-Gloriosso-Liu, which however mostly uses it in a static black hole background with slowly-varying probe dynamics. This talk is based on an attempt to implement this prescription in a truly dynamical geometry that is dual to a Bjorken flow in the boundary- a simple toy model describing the expansion and cooling of the hadronic matter produced in the heavy- ion collision. We will explicitly compute the SK correlations of the scalar fluctuations of the Bjorken flow in a systematic late-time expansion, amenable to a Borel resummation. In this context, I will also discuss our newly developed matrix method which reproduces various known results and also gives an elegant way of computing the SK correlation functions beyond equilibrium. Finally, I will conclude with a set of open problems in this context.

Tuesday 6 December 2022, 15:00 at LPTHE, library & Zoom link in comments
( Join Zoom Meeting https://cern.zoom.us/j/61239718813?pwd=ZjdmaDJ6c2h5eWpITk5yd0pDTDlTUT09 Meeting ID: 612 3971 8813 Passcode: 918259 )
LPTHE-PPH (Particle Physics at LPTHE) hep-ph
V. Ravindran ( IMSc Chennai ) Resummation of next to soft virtual terms for rapidity distributions of Drell-Yan and Higgs productions at the LHC
Abstract: We present a formalism that resums both threshold enhanced logarithms and their subleading contributions to all orders in perturbative Quantum Chromodynamics for the rapidity distribution of any colorless particle produced in hadron colliders. We achieve this by exploiting the factorization properties and K+G equations satisfied by the soft and virtual parts of the cross section. We compute for the first time, the resummed result in two dimensional Mellin space up to N3LL accuracy. Using various state-of- the-art multi-loop and multi-leg results, we demonstrate the numerical impact of the resummed results up to next-to-next-to leading order for the rapidity distributions of Drell-Yan and of the Higgs boson at the Large Hadron Collider. We find that these threshold logs in the resummed result stabilise the predictions against renormalization and factorization scale variations.

Wednesday 7 December 2022, 11:00 at LKB, Amphi Charpak – Sorbonne université – 4 place Jussieu – 75005 Paris SEM-LKB (Séminaire du Laboratoire Kastler Brossel) quant-ph
Jacqueline Bloch Excitonic polaritons in semiconductor lattices: emulating condensed matter physics

Wednesday 7 December 2022, 14:00 at IHES, Amphithéâtre Léon Motchane
( Cours de l'IHES )
MATH-IHES (TBA) math
Yilin Wang ( IHES ) The Loewner Energy at the Crossroad of Random Conformal Geometry and Teichmueller Theory (3/4)
Abstract: The Loewner energy for Jordan curves first arises from the large deviations of Schramm-Loewner evolution (SLE), a family of random fractal curves modeling interfaces in 2D statistical mechanics. In a certain way, this energy measures the roundness of a Jordan curve, and we show that it is finite if and only if the curve is a Weil-Petersson quasicircle and connect it to determinants of Laplacians. Furthermore, the Loewner energy is a Kahler potential on the Weil-Petersson Teichmueller space identified with the space of Weil-Petersson quasicircles. Intriguingly, this class of finite energy curves has more than 20 equivalent definitions arising in very different contexts, including Teichmueller theory, geometric function theory, hyperbolic geometry, spectral theory, and has been studied since the eighties with motivations from string theory. The myriad of perspectives on this class of curves is both luxurious and mysterious. I will overview the links between Loewner energy and SLE, Weil-Petersson quasicircles, and other branches of mathematics it touches on. I will highlight how ideas from random conformal geometry inspire new results on Weil-Petersson quasicircles and discuss further directions.

Thursday 8 December 2022, 10:00 at IHP, Grisvard (314) RENC-THEO (Rencontres Théoriciennes) hep-th
Nat Levine ( ENS Paris ) Bootstrapping bulk locality
Abstract: Field theories in AdS give rise to CFTs through their boundary correlators. Conversely, only special CFTs correspond to local bulk theories. We study the constraints imposed by bulk locality and the reconstruction of bulk fields as a bootstrap problem. By constructing a complete basis of functionals, we recast the locality constraint as a list of sum rules on the Boundary Operator Expansion and boundary OPE data. These sum rules are "dual" to the Generalized Free Field spectrum, and we also engineer a large family of "interacting" bases of functionals that naturally bootstrap interacting solutions. We discuss the flat- space limit, when the locality problem becomes that of constructing local form factors from an S-matrix.

Thursday 8 December 2022, 11:45 at IHP, Grisvard (314) RENC-THEO (Rencontres Théoriciennes) hep-th
Laurentiu Rodina ( Queen Mary U. London ) The geometry of EFT and CFT
Abstract: I will show that the space of EFT couplings and the space of 2D CFT partition functions can be described by identical geometries known as "moment problems" in the mathematics literature. Using Minkowski sums one can bootstrap both geometries analytically, including constraints which so far have been less explored. These include the unitarity upper bound and low spin dominance (for EFT) and degeneracy integrality (for CFT), leading to interesting reductions in allowed theory space.

Thursday 8 December 2022, 14:00 at LPTHE, INSP Jussieu towers 22-23 room 3-17 TQM (Theory of quantum matter) cond-mat
Nicolas Dupuis ( LPTMC ) One-dimensional disordered Bose fluid: from Bose glass to Mott glass
Abstract: In a one-dimensional Bose fluid, disorder can induce a quantum phase transition between a superfluid phase (Luttinger liquid) and a localized phase (Bose glass). Using bosonization, the replica method and a nonperturbative functional renormalization-group approach, we find that the Bose-glass phase is described by a fully attractive strong-disorder fixed point characterized by a singular disorder correlator whose functional dependence assumes a cuspy form. This reveals the glassy properties (pinning, "shocks" and "avalanches") due to the existence of metastable states, as well as the crucial role of quantum tunneling between different metastable configurations. We also show that long-range interactions can stabilize a Mott glass, i.e. a state intermediate between a Mott insulator and a Bose glass, and characterized by a vanishing compressibility and a gapless optical conductivity.

Thursday 8 December 2022, 14:00 at IHES, Amphithéâtre Léon Motchane
( Cours de l'IHES )
MATH-IHES (TBA) math
Yilin Wang ( IHES ) The Loewner Energy at the Crossroad of Random Conformal Geometry and Teichmueller Theory (4/4)
Abstract: The Loewner energy for Jordan curves first arises from the large deviations of Schramm-Loewner evolution (SLE), a family of random fractal curves modeling interfaces in 2D statistical mechanics. In a certain way, this energy measures the roundness of a Jordan curve, and we show that it is finite if and only if the curve is a Weil-Petersson quasicircle and connect it to determinants of Laplacians. Furthermore, the Loewner energy is a Kahler potential on the Weil-Petersson Teichmueller space identified with the space of Weil-Petersson quasicircles. Intriguingly, this class of finite energy curves has more than 20 equivalent definitions arising in very different contexts, including Teichmueller theory, geometric function theory, hyperbolic geometry, spectral theory, and has been studied since the eighties with motivations from string theory. The myriad of perspectives on this class of curves is both luxurious and mysterious. I will overview the links between Loewner energy and SLE, Weil-Petersson quasicircles, and other branches of mathematics it touches on. I will highlight how ideas from random conformal geometry inspire new results on Weil-Petersson quasicircles and discuss further directions.

Monday 12 December 2022, 14:00 at IHES, Amphithéâtre Léon Motchane
( Séminaire Géométrie et groupes discrets )
MATH-IHES (TBA) math
Jean Raimbault ( Aix-Marseille Université ) Thin Parts of Arithmetic Locally Symmetric Spaces
Abstract: The well-known collar or Margulis lemma describes the structure of negatively curved manifolds at mesoscopic scale, in particular it allows to describe these manifolds globally through the "thick-thin decomposition". This is not sufficient, however, to completely understand the homotopy type of the manifold, even roughly. In this talk I will describe an "arithmetic Margulis lemma" (essentially a consequence of work of E. Breuillard) which allows to describe thin parts at a macroscopic scale in certain circumstances, and how to use it to obtain sharp bounds on the volume of thin parts of arithmetic locally symmetric spaces. This is joint work with M. Frączyk and S. Hurtado.

Monday 12 December 2022, 16:00 at IHES, Amphithéâtre Léon Motchane
( Séminaire Géométrie et groupes discrets )
MATH-IHES (TBA) math
Greg Kuperberg ( UC Davis & IHES ) Effective Approximation in Densely Generated Lie Groups
Abstract: If a finite set S densely generates a compact, semisimple Lie group G, then how well does the set of words of length &#8467; in S (and S-1) approximate G? We could ask for them words to be an &#949;-net of G; or, beyond an &#949;-net, we could ask for the words to be evenly distributed down to a scale of &#949;; or we could ask for an efficient algorithm to produce a word that lies within &#949; of any given g in G. An optimal statistical result, with &#8467; = O(log 1/&#949;), was first established by Lubotzky, Phillips, and Sarnak when G = SU(2) for special choices of S; and later generalized by others, but still with some restrictions on S. Not long afterwards, in the context of quantum computing, Solovay and Kitaev independently established an algorithm to find a word with &#8467; = O((log 1/&#949;)a) for any S and (initially) also G = SU(2). I will discuss the current status of different versions of this question, including versions when G might not be compact or S-1 might not be used. I will also discuss my own result, in which I improve the exponent in the (algorithmic) Solovay-Kitaev theorem from the previous best value of a = 3+&#948; to a = (log&#966; 2) + 1 + &#948; < 2.4405.

Tuesday 13 December 2022, 11:00 at IPHT, Amphi Claude Bloch, Bât. 774 IPHT-GEN (Séminaire général du SPhT) physics
David Andelman ( (School of Physics, Tel Aviv University) ) One hundred years of electrified interfaces: What?s new with the theories of Debye and Onsager?
Abstract: The Poisson-Boltzmann theory stems from the pioneering works of Debye and Onsager and is considered even today as the benchmark of ionic solutions and electrified interfaces. It has been instrumental during the last century in predicting charge distributions and interactions between charged surfaces, membranes, electrodes, macromolecules, and colloids. The electrostatic model of charged fluids, on which the Poisson-Boltzmann description rests and its statistical mechanical consequences have been scrutinized in great detail. Much less, however, is understood about its probable shortcomings when dealing with various aspects of real physical, chemical, and biological systems. After reviewing the Poisson-Boltzmann theory, I will discuss several extensions and modifications to the seminal works of Debye and Onsager as applied to ions and macromolecules in confined geometries. These novel ideas include the effect of dipolar solvent molecules, finite size of ions, ionic specificity, surface tension, and conductivity of concentrated ionic solutions.

Tuesday 13 December 2022, 11:00 at LPTMS, Salle des séminaires du FAST et du LPTMS, bâtiment Pascal n°530
( Hybrid: onsite seminar + zoom. For zoom info, please write to valentina.ros@universite-paris-saclay.fr or check LPTMS website http://lptms.u-psud.fr/en/ )
LPTMS (Séminaire du Laboratoire de Physique Théorique et Modèles Statistiques (Orsay)) cond-mat.stat-mech
Martin Robert-De-Saint-Vincent ( Laboratoire de Physique des Lasers ) Manipulating the spins of degenerate SU(10)-symmetric fermi gases
Abstract: Ultracold alkaline-earth atoms offer the possibility to study the effect of a large spin degree of freedom in interacting fermionic ensembles. I will present the recent developments of our experiment, on which we produce degenerate Fermi gases of strontium 87, held in optical lattices to realize the Fermi-Hubbard model generalized to large-spin atoms (F = 9/2). In this seminar, I will focus on our capabilities for measurement and control of the spins, and connect this to our intended approach for the study of the antiferromagnetic Heisenberg model of magnetism. For our atomic species, the spins are of nuclear nature, which is both a strength and a complication as standard spin measurement or manipulation schemes based on magnetic gradients are ineffective. I will show nevertheless that a narrow line with large hyperfine structure offers us very powerful tools, associated with the engineering of effective spin-orbit coupling, that we will use on several central aspects of our studies. First, we applied adiabatically a three-level coupling involving a dark atomic state, reminiscent of EIT or STIRAP, to transfer momentum in a spin-selective manner [1]. This, we now use for spin measurements, and could provide information through spin-momentum noise correlations. Second, we have demonstrated controlled coherent adiabatic operations in the 10-component spin-manifold, on degenerate gases prepared deterministically in a single spin state. I will connect this to our present effort at using microstructured optical fields to adiabatically reach low-energy states of the Heisenberg Hamiltonian, by the controlled breaking of its symmetries [2]. [1] P. Bataille et. al., Phys. Rev. A 102, 013317 (2020). [2] Comparin et.al., Phys. Rev. Lett. 129, 113201 (2022)

Tuesday 13 December 2022, 14:00 at LPENS, L357/L359 (24 Rue Lhomond) LPTENS-HE (Séminaire commun LPTENS-LPTHE) hep-th
Nicolas Kovensky ( IPhT, Saclay ) A proof for string three-point functions in AdS3
Abstract: Correlation functions of the SL(2,$\R$)-WZW model involving spectrally flowed vertex operators are notoriously difficult to compute. An explicit integral expression for the corresponding three-point functions was recently conjectured in [2105.12130]. Here we provide the proof for this conjecture. For this we extend the methods of [2208.00978] based on the so-called SL(2,$\R$) series identifications, which relate vertex operators belonging to "adjacent" spectral flow sectors.

Wednesday 14 December 2022, 14:00 at LPENS, L357 FORUM-ENS (Forum de Physique Statistique @ ENS) cond-mat.stat-mech
Annette Zippelius ( Georg-August-Universität Göttingen ) Active droplets

Thursday 15 December 2022, 11:00 at LPTHE, bibliothèque du LPTHE, tour 13-14, 4eme étage SEM-DARBOUX (Séminaire Darboux - physique théorique et mathématiques) hep-th
Javier Fresan TBA

Thursday 5 January 2023, 14:00 at LPTHE, Bibliothèque LPTHE 13-14 4th floor TQM (Theory of quantum matter) math-ph
Kareljan Schoutens ( University of Amsterdam ) Kink Dynamics and Quantum Simulation of Supersymmetric Lattice Hamiltonians (provisoire)
Abstract: TBA

Monday 9 January 2023, 13:30 at LPENS, L357 LPENS-MDQ (Séminaire Matériaux et Dispositifs Quantiques du LPENS) cond-mat
Isabella Bovente ( Thales TRT ) TBA

Tuesday 10 January 2023, 11:00 at LPTMS, Salle des séminaires du FAST et du LPTMS, bâtiment Pascal n°530
( Hybrid: onsite seminar + zoom. For zoom info, please write to valentina.ros@universite-paris-saclay.fr or check LPTMS website http://lptms.u-psud.fr/en/ )
LPTMS (Séminaire du Laboratoire de Physique Théorique et Modèles Statistiques (Orsay)) cond-mat.stat-mech
Andrei Rotaru ( LPTHE ) TBA

Wednesday 11 January 2023, 13:30 at DPT-PHYS-ENS, ConfIV (E244) - 24 rue Lhomond 75005 PARIS COLLOQUIUM-ENS (Colloquium of the Physics Department of ENS) physics
Prix Des Trois Physiciens TBA

Tuesday 17 January 2023, 11:00 at LPTMS, Salle des séminaires du FAST et du LPTMS, bâtiment Pascal n°530
( Hybrid: onsite seminar + zoom. For zoom info, please write to valentina.ros@universite-paris-saclay.fr or check LPTMS website http://lptms.u-psud.fr/en/ )
LPTMS (Séminaire du Laboratoire de Physique Théorique et Modèles Statistiques (Orsay)) cond-mat.stat-mech
Luca Salasnich ( University of Padova ) TBA

Thursday 19 January 2023, 10:00 at IHP, 314 RENC-THEO (Rencontres Théoriciennes) hep-th
Fabio Apruzzi ( U Padova ) TBA

Thursday 19 January 2023, 11:00 at IHES, Amphithéâtre Léon Motchane MATH-IHES (TBA) math
Shuddhodan Kadattur Vasudevan ( IHES ) Brylynski-Radon Transform in Characteristic p > 0
Abstract: Brylynski defined and studied the topological analogue of the Radon transform on Grassmannians over Complex numbers. Using techniques from the theory of D-modules he characterized the image of these Radon transforms in terms of their singular supports. In this talk, we shall discuss a characteristic p > 0 analogues of Brylynski’s work on the characterization of the image of the Radon transform and obtain a precise description in terms of Beilinson-Saito's theory of singular support. This is joint work with Deepam Patel.

Thursday 19 January 2023, 14:00 at LPTHE, INSP Jussieu towers 22-23 room 3-17 TQM (Theory of quantum matter) hep-th
Karim Noui ( IJC Lab Orsay ) TBA (revue sur les spin-networks en gravitation quantique et le liens avec les théories topologiques)
Abstract: TBA

Wednesday 25 January 2023, 13:30 at DPT-PHYS-ENS, ConfIV (E244) - 24 rue Lhomond 75005 PARIS COLLOQUIUM-ENS (Colloquium of the Physics Department of ENS) physics
Philippe Corboz ( University of Amsterdam ) TBA

Thursday 26 January 2023, 11:00 at LPTHE, bibliothèque du LPTHE, tour 13-14, 4eme étage SEM-DARBOUX (Séminaire Darboux - physique théorique et mathématiques) hep-th
Carl Tipler TBA

Tuesday 31 January 2023, 11:00 at LPTMS, Salle des séminaires du FAST et du LPTMS, bâtiment Pascal n°530
( Hybrid: onsite seminar + zoom. For zoom info, please write to valentina.ros@universite-paris-saclay.fr or check LPTMS website http://lptms.u-psud.fr/en/ )
LPTMS (Séminaire du Laboratoire de Physique Théorique et Modèles Statistiques (Orsay)) cond-mat.stat-mech
Igor Bodrenko ( Cagliari University ) TBA

Thursday 2 February 2023, 14:00 at LPTHE, INSP Jussieu towers 22-23 room 3-17 TQM (Theory of quantum matter) cond-mat.mes-hall
Anne Anthore ( C2N Palaiseau & Université Paris Cité ) TBA

Tuesday 7 February 2023, 11:00 at LPTMS, Salle des séminaires du FAST et du LPTMS, bâtiment Pascal n°530
( Hybrid: onsite + zoom. For zoom please write to valentina.ros@universite-paris-saclay.fr or check LPTMS website http://lptms.u-psud.fr/en/activites/seminaires/ )
LPTMS (Séminaire du Laboratoire de Physique Théorique et Modèles Statistiques (Orsay)) cond-mat.stat-mech
Sanjay Moudgalya ( Stanford ) TBA

seminars from series at institute
in subject with field matching

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