Mercredi 30 Octobre 2024, 14:00 à LPENS, Bibl. Phys. Th. E238	LPENS-BQ (Balades Quantiques de le LPENS)	cond-mat
Jaewon Kim ( UC Berkeley )	Error Threshold of SYK Codes from Strong-to-Weak Parity Symmetry Breaking
Abstract:	Quantum error correction (QEC) codes fundamentally link to quantum phases of matter; the degenerate ground state manifold corresponds to the code space, while topological excitations represent error syndromes. Extending this idea, the Sachdev-Ye-Kitaev (SYK) model, characterized by its extensive quasi- ground state degeneracy, serves as a constant rate approximate QEC code. In this work, we study the impacts of decoherence on the information-theoretic capacity of SYK models and their variants. We calculate the coherent information in the maximally entangled quasi-ground state space of the SYK models under the quasiparticle parity breaking and parity conserving noise. Interestingly, we found that under the strong fermion parity symmetric noise, the mixed state undergoes the strong to weak spontaneous symmetry breaking of fermion parity, which also corresponds to the information-theoretic transition. Our results provide critical insights into the behavior of approximate constant-rate QEC codes under decoherence.

Jeudi 31 Octobre 2024, 11:00 à IHES, Amphithéâtre Léon Motchane	MATH-IHES (TBA)	math
Dan Petersen ( Stockholm University )	A Classifying Space for the Handlebody Group
Abstract:	We use Teichmüller theory to construct a new geometric model for the classifying space of the mapping class group of a three-dimensional handlebody. Two consequences are obtained: (i) Chan-Galatius-Payne have recently shown that the homology of Kontsevich's commutative graph complex injects into the homology of the mapping class groups of surfaces, producing an enormous amount of highly unstable homology classes. We show that this homomorphism factors through the homology of the corresponding handlebody mapping class groups. (ii) The handlebody mapping class group is a virtual duality group in the sense of Bieri-Eckmann, with dualizing module given by a certain complex of nonsimple disk systems; the analogous result for mapping class groups of surfaces is a theorem of Harer. (Joint with Louis Hainaut and with Ric Wade.)

Jeudi 31 Octobre 2024, 11:00 à LPENS, L378, 24 Rue Lhomond	LPTENS-HE (Séminaire commun LPTENS-LPTHE)	hep-th
Adam Chalabi ( NBI Copenhagen )	Correlation functions for disorder-type defects in N=4 super-Yang-Mills theory
Abstract:	The admissible boundary conditions and defects of a given quantum field theory are fundamental pieces of information that characterise it. Although finding the space of admissible boundaries and defects is generally difficult, much progress can be made for highly symmetric systems that enjoy conformal symmetry and/or supersymmetry. In this talk I will discuss 1/2-BPS superconformal defects in N=4 super-Yang-Mills theory and closely related systems, which are specified by imposing singularity conditions at the location of the defect. By focusing on simple correlation functions in the presence of such defects, I will describe how characteristic data can be extracted using perturbation theory, (super-)conformal symmetry, and integrability.

Jeudi 31 Octobre 2024, 14:00 à IHES, Amphithéâtre Léon Motchane	PT-IHES (Séminaire de physique théorique de l'IHES)	physics
Giovanni Rizi ( IHES )	Intro to the SymTFT
Abstract:	The Symmetry Topological Field Theory (SymTFT) is a realization of the philosophy that symmetries in Quantum Field Theory (QFT) can be studied using tools from Topological Quantum Field Theory (TQFT). In this talk, I will introduce this topic and motivate the construction of the SymTFT for a d-dimensional QFT as a (d+1)-dimensional topological field theory. I will explain how this (d+1)-dimensional theory is completely determined by the global symmetries of the d-dimensional QFT, making it "universal" for all d-dimensional theories sharing the same symmetries. A significant advantage of the SymTFT is its ability to separate kinematical aspects from dynamical ones. This separation enables the analysis of the constraints imposed by a given symmetry structure on the dynamics, with a prime example being 't Hooft anomalies, using only TQFT tools and observables.

Jeudi 31 Octobre 2024, 14:00 à LPTMC, Jussieu, LPTMC seminar room, towers 13-12, 5th floor, room 523	SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée)	cond-mat
Benjamin Wieder ( IPhT Saclay )	Monopole Quantum Numbers and Projective Representations in Stable and Fragile Topological Crystalline Insulators
Abstract:	Over the past 15 years, a dizzying array of noninteracting topological insulator (TI) and topological crystalline insulator (TCI) phases have been theoretically predicted and identified in real materials. While the TI states are well understood, the TCI states – which comprise the majority of topological materials in nature – exhibit more complicated classification groups and boundary states and carry more ambiguous response signatures. For earlier variants of interacting symmetry-protected topological states (SPTs), both the classification and response were clarified through the many-body quantum numbers of the 0D collective excitations bound to crystal and electromagnetic defects, such as magnetic fluxes and monopoles. In particular, when 0D defects exhibit fractionalized quantum numbers, or more generally projective representations of the local many-body symmetry group, this can indicate the presence of quantized responses in the bulk that are governed by long-wavelength topological field theories that are stable to symmetric interactions. In this talk, I will introduce numerical methods for computing defect quantum numbers in stable and fragile TCI states via the reduced density matrix, revealing a deep connection between defect quantum numbers and the entanglement spectrum. Surprisingly, we find that when crystal symmetries are included in the local symmetry group, defects can appear to transform projectively even in Wannierizable (fragile) insulators, casting doubt on the suitability of magnetic monopoles for characterizing the TCI states present in real 3D materials. Our results represent a crucial step towards describing TCIs beyond tight-binding models and frameworks like “higher- order topology,” and facilitate more direct connections between free-fermion TCIs and interacting SPTs.

Lundi 4 Novembre 2024, 14:00 à IHES, Amphithéâtre Léon Motchane ( Séminaire Géométrie et groupes discrets )	MATH-IHES (TBA)	math
Martin Bobb ( MPIMS Leipzig )	Affine Laminations and Coaffine Representations
Abstract:	We consider certain representations of a surface group into PGL(4,R) called convex cocompact coaffine representations. These representations act geometrically on a 3-dimensional convex body in projective space, and are part of a broader (and more difficult) landscape of such geometric actions. From classical cases, we would anticipate an analytic object called a transverse measured lamination to capture the geometry of these representations, however paradoxical examples reveal that a generalization is necessary. We will discuss a nice resolution to these difficulties, and describe a space of affine measured laminations which parametrize the space of convex cocompact coaffine representations. Along the way we make an interesting connection to the dynamics of affine interval exchange transformations. Joint work with James Farre.

Lundi 4 Novembre 2024, 14:00 à LPNHE, Salle des seminaires (1222-RC/SB-08)	LPNHE (Séminaires du LPNHE)	physics
Afiq Aize ( DESY )	In Search of Top Quark Pairs With Zero Total Angular Momentum
Abstract:	The CMS Collaboration has recently publicized a search for heavy pseudoscalar or scalar bosons decaying to a top quark pair in final states with one or two charged leptons, using 138 fb-1 of proton-proton collisions at sqrt(s) = 13 TeV. In this search, an excess of the data above the background prediction, as modeled using perturbative quantum chromodynamics only, is observed with a significance of above five standard deviations. In my presentation, I will discuss the properties of the excess as established within the scope of the search. This includes its position, which is close to the top pair production threshold, as well as its spin quantum numbers. In addition, I will discuss interpretations of the data in terms of a color singlet pseudoscalar bound state of top quark pairs, and in terms of a generic spin-0 boson whose resonant production interferes with the top pair continuum. I will also discuss this result in a wider context, in particular the interplay between it and existing experimental measurements.

Lundi 4 Novembre 2024, 16:00 à IHES, Amphithéâtre Léon Motchane ( Séminaire Géométrie et groupes discrets )	MATH-IHES (TBA)	math
Antonin Guilloux ( IMJ-PRG )	Limit Sets of Divergent Sequences of Schottky Groups
Abstract:	For divergent sequences of Schottky groups of the N-dimensional hyperbolic space HN, the Hausdorff dimension of the limit sets typically goes to zero. By considering actions of these groups on the infinite-dimensional hyperbolic space, we give an asymptotic for this convergence. This is joint work with Gilles Courtois. It is partly inspired by recent work of Dang-Mehmeti. If time permits, I will compare the two approaches.

Mardi 5 Novembre 2024, 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
Gwendal Fève ( LPENS, Sorbonne )	Anyon braiding in mesoscopic colliders
Abstract:	In three-dimensional space, elementary particles are divided between fermions and bosons according to the properties of symmetry of the wave function describing the state of the system when two particles are exchanged. The situation is different in two-dimensional systems which can host exotic quasiparticles, called anyons, which obey intermediate quantum statistics characterized by an exchange phase varying between and [1,2]. As a consequence, contrary to fermions and bosons, anyons keep a robust memory of braiding operations, which consist in moving one anyon around another one. In particular anyons have been predicted to the be the elementary excitations of the fractional quantum Hall regime, obtained by applying a strong magnetic field perpendicular to a two-dimensional conductor. I will discuss recent experiments realized in fractional quantum Hall conductors to demonstrate the fractional statistics of anyons [3, 5-6], focusing on the anyon collider geometry [7], where anyon braiding can be revealed by studying the partitioning of dilute anyon beams by a beam splitter. References: [1] B. I. Halperin, Phys. Rev. Lett. 52, 1583–1586 (1984). [2] D. Arovas, J. R. Schrieffer, F. Wilczek, Phys. Rev. Lett. 53, 722–723 (1984). [3] H. Bartolomei et al., Science 368, 173 (2020). [4] J. Nakamura S. Liang, G. C. Gardner, and M. J. Manfra, Nature Physics 16, 931 (2020). [5] M. Ruelle et al., Phys. Rev. X 13, 011031 (2023). [6] M. Ruelle et al., arXiv:2409.08685 (2024) [7] B. Rosenow, I. P. Levkivskyi, B. I. Halperin, Phys. Rev. Lett. 116, 156802 (2016).

Mardi 5 Novembre 2024, 14:00 à IPHT, Salle Claude Itzykson, Bât. 774	IPHT-HEP (Séminaire de physique des particules et de cosmologie)	hep-ph
Rodrigo Alonso ( Durham University )	Fractional-Charge Hadrons and Leptons to Tell the Standard Model Group Apart
Abstract:	Generalised symmetries have expanded our insight into theory but their impact has not fully translated into phenomenology yet. This talk will present a case study that bridges the two fields and aims at being approachable from either end. The gauge group of strong and electroweak interactions in Nature could be any of the four that share the same Lie algebra but have different one form discrete symmetries. Each of these cases allows in its spectrum for the matter fields of the SM but also for new distinctive representations which follow a group-dependent electric charge quantisation rule.

Mardi 5 Novembre 2024, 14:00 à LPTHE, library	LPTHE-PPH (Particle Physics at LPTHE)	hep-ph
Luca Maxia ( University of Groningen )	Exploring Quarkonium physics at small transverse momentum
Abstract:	Despite more than 50 years of research on protons and their partonic constituents, the complete picture is still obscure, especially if one includes polarisation and transverse momentum effects. While recent works have performed direct extractions of quark transverse momentum dependent distributions (TMD) of protons, the same knowledge about gluon distributions lags behind. Thus, it is crucial to identify observables that are sensitive to gluons. Accordingly, quarkonia are key tools to access gluon TMDs, allowing us to explore lower energy scales as compared, for instance, to Higgs production. However, doubts persist on the correct underlying formation mechanism of quarkonia, and the formalism to accurately describe their production at small transverse momentum. In this talk I will present some recent works published in the 2020s. The first part focuses on the opportunities and challenges of using the non-relativistic QCD (NRQCD) approach to describe quarkonium production at small transverse momentum. In the second part, I will discuss observables measurable at either the future Electron-Ion Collider or the LHC that can help shed light on the gluon content of protons.

Mercredi 6 Novembre 2024, 11:00 à LKB, Sorbonne Université - 4 places Jussieu 75005 - Amphi Astier	SEM-LKB (Séminaire du Laboratoire Kastler Brossel)	quant-ph
Pierre Bon ( XLIM, Université de Limoges/CNRS )	Scalar Electromagnetic Field imaging without reference and with nanoscale resolution on living biological samples
Abstract:	Accessing the phase of a light beam in addition to its intensity drastically increases the amount of information that can be extracted from light. The development of compact and self-referenced interferometry solutions has opened the field to high-resolution measurement of the scalar electromagnetic field on any type of beam without the need for an external reference. This modality proves to be particularly interesting as it allows measurement of optical path differences as small as 10pm in single shot. Applied to microscopy of semi-transparent biological samples, it allows to infer biophysical information including their mass, nature, position, or even the presence of temperature variations at very high resolution. Recently, to push the resolution of quantitative phase imaging beyond limit, we have proposed a solution to bypass the diffraction limit (so-called super-resolution imaging) on any sample. This approach now enables the imaging of electromagnetic fields with a resolution better than 100 nm while remaining compatible with the observation of fragile 3D samples such as organoids.

Mercredi 6 Novembre 2024, 13:30 à IHP, Maryam Mirzakhani (a.k.a. Salle 201 on 2nd floor) ( Kick-off event for the trimester "New trends in QFT, modularity, resurgence". To attend in-person, register at: indico.math.cnrs.fr/event/13003/registrations. )	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Antoine Tilloy ( LPENS & Mines Paris & Inria Paris )	A variational approach to QFT in low dimensions?
Abstract:	Massive quantum field theories in $1+1$ dimensions are interesting in that they are fairly easy to define rigorously but still very difficult to solve (except at some integrable points). In the past few years, my collaborators and I have introduced and developed a variational method to solve them. The variational ansatz is based on a combination of continuous matrix product states and Bogoliubov transform. It is mathematically interesting in that it is in principle arbitrarily precise, works in the continuum and in the thermodynamic limit directly, and gives rigorous bounds to the energy density of the vacuum. I will motivate this variational class, explain what models we already applied it to, and list the many open problems ahead to make it a fully general method to solve generic QFT in $1+1d$.

Mercredi 6 Novembre 2024, 14:00 à LPENS, E239 (Bibliothèque de physique théorique) ( unusual time and venue )	FORUM-ENS (Forum de Physique Statistique @ ENS)	cond-mat.stat-mech
Antoine Mouzard ( Université Paris Nanterre )	TBA

Mercredi 6 Novembre 2024, 14:45 à IHES, Amphithéâtre Léon Motchne ( Séminaire Amplitudes et Gravitation sur l'Yvette (IHES/IPhT) )	PT-IHES (Séminaire de physique théorique de l'IHES)	hep-th
Paolo Arnaudo ( University of Southampton )	Schwarzschild Quasinormal Modes and the Small Frequency Expansion
Abstract:	We consider linear perturbations around the Schwarzschild black hole in four dimensions. We describe two methods that provide the quantization condition for the quasinormal mode frequencies of the perturbation field. The first method is based on techniques from supersymmetric gauge theory and conformal field theory that allow to explicitly write the connection coefficients for the differential equation encoding the spectral problem. The second method is based on a small-frequency expansion of the solutions of the differential equation, and permits to obtain the corresponding expansion for the elements of the scattering matrix, which have poles in the quasinormal mode frequencies. The relations between the two approaches will be discussed, together with the respective advantages.

Mercredi 6 Novembre 2024, 15:00 à IHP, Maryam Mirzakhani (a.k.a. Salle 201 on 2nd floor) ( Kick-off event for the trimester "New trends in QFT, modularity, resurgence". To attend in-person, register at: indico.math.cnrs.fr/event/13003/registrations. )	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Campbell Wheeler ( IHES )	Matrix cocycles and Borel resummation
Abstract:	One of the many miracles of modular forms is that their $q$-series have convergent asymptotics as q approaches roots of unity. This comes by analysing the action of $SL(2,\mathbb{Z})$ and the knowledge of the behaviour as $q$ tends to zero. In Ramanujan's last letter to Hardy, he famously introduced the mysterious mock modular forms. These were $q$-series with asymptotics that look like those of a modular form at roots of unity. However, after removing the leading order, there was a new divergent series that appeared, which obstructed modularity. Thanks to work of Zwegers, it has long (at least implicitly) been known that this failure of modularity can be packaged into an $SL(2,\mathbb{Z})$ cocycle that gives rise to the Borel resummation of the associated asymptotic series. More recently, Garoufalidis-Zagier studied quantum modular forms where similar statements were then conjectured by Garoufalidis-Gu-Mariño. I will outline a proof that cocycles associated to quantum modular forms are the Borel re-summation of associated asymptotic series in an infinite family of examples. This proves that asymptotic series associated to the $4_1$ and $5_2$ knots are Borel summable. This is based on joint work with Veronica Fantini.

Mercredi 6 Novembre 2024, 16:30 à IHP, Maryam Mirzakhani (a.k.a. Salle 201 on 2nd floor) ( Kick-off event for the trimester "New trends in QFT, modularity, resurgence". To attend in-person, register at: indico.math.cnrs.fr/event/13003/registrations. )	SEED (Seed Seminar of Mathematics and Physics)	math-ph
Claudia Rella ( IHES )	The arithmetic of resurgent topological strings
Abstract:	Quantising the mirror curve to a toric Calabi-Yau threefold gives rise to quantum operators whose fermionic spectral traces produce factorially divergent series in the Planck constant and its inverse. These are captured by the Nekrasov-Shatashvili and standard topological strings via the TS/ST correspondence. In this talk, I will discuss the resurgence of these dual asymptotic series and present an exact solution for the spectral trace of local $P^2$. A full-fledged strong-weak symmetry exchanges the perturbative/nonperturbative contributions to the holomorphic and anti- holomorphic blocks in the factorisation of the spectral trace, and it builds upon the interplay of the L-functions with coefficients given by the Stokes constants and the q-series acting as their generating functions. Guided by this crucial example, I will propose a new perspective on the resurgence of particular formal power series, which are conjectured to possess specific summability and quantum modularity properties, leading us to introduce the general paradigm of modular resurgence. This talk is based on arXiv:2212.10606, 2404.10695, and 2404.11550.

Jeudi 7 Novembre 2024, 11:00 à IHES, Amphithéâtre Léon Motchane ( Séminaire de Géométrie Arithmétique )	MATH-IHES (TBA)	math
Hiroki Kato ( IHES )	Bernstein-Sato Theory in Positive Characteristic and Unit Root Nearby Cycles
Abstract:	: In the setting of algebraic geometry in characteristic zero (or of complex geometry), the Bernstein-Sato polynomial is a polynomial defined for a function on a smooth variety and has deep connections with several invariants attached to the singularities of the zero locus of the function, among which the focus in the talk is on the connection with the monodromy eigenvalues on the nearby cycle sheaf, known as the theorem of Kashiwara and Malgrange. There have been attempts to develop a Bernstein-Sato-type theory also in the setting of positive characteristic, and these have led to a definition of Bernstein-Sato roots (but not their multiplicities), which again has deep connections to the theory of singularities. However, it has not been well studied how this theory is related to the monodromy eigenvalues on a nearby cycle sheaf. In this talk, I will explain an observation that the Bernstein-Sato roots seem to recover some of the monodromy eigenvalues on a suitable nearby cycle sheaf but only those on the unit root part, which we think suggests a better definition of Bernstein-Sato roots that captures all the monodromy eigenvalues and produces finer information about the singularities of the zero locus. This is a joint work in progress with Eamon Quinlan-Gallego and Daichi Takeuchi.

Jeudi 7 Novembre 2024, 14:00 à LPTM, 4.13b	SEM-LPTM-UCP (Seminaires du LPTM , Universite de Cergy Pontoise)	math-ph
Giuseppe Vitagliano ( Center for Quantum Science and Technology, T.U. Wien )	Entanglement detection with collective measurements in many-body systems
Abstract:	I will present some recent results on entanglement detection and quantification with collective measurements in many-body ensembles. First I will give an introduction into entanglement and the idea of 'spin squeezing', which was introduced in the context of metrology, and explain the relation between the two concepts. I will show how the original spin squeezing approach can be generalized in several respects and how it allows to quantify multipartite entanglement in different types of experimentally-controlled many-body systems, such as cold atomic clouds or solid-state magnetic materials. These entanglement witnesses are based on variances of collective operators, which can be extracted from simple averaged two-body correlation functions, which is the reason why they find widespread application in many-body systems, where higher-order correlation functions of more complex measurements are generally very challenging. In particular I will present particular examples of criteria that have been recently applied to quantify entanglement in experiments with cold or ultracold atomic gases. Similarly, I will present criteria tailored to detect bipartite entanglement in a many-body state split in two spatially separated sub-ensembles. In the final part, I will focus on the quantification of entanglement by means of entanglement monotones with similar methods, and again, as a concrete application, I will show the results of applying this method with experimental data of a spin-squeezed Bose-Einstein condensates of ∼500 atoms.”

Mardi 12 Novembre 2024, 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
Jean-Noël Fuchs ( LPTMC )	Panorama of topological phases of matter
Abstract:	In this talk, I will try to give a pedagogical overview of phases of matter that are classified using ideas from topology rather than symmetry. I will insist on the difference between two families of such phases of matter: topological insulators and topological order. On the one hand, topological insulators can be seen as a refinement of band insulators, in which bands carry topological invariants (for example, Chern numbers) such that several classes of insulators can be distinguished. This is a generalization of ideas of D. Thouless and co-workers concerning the integer quantum Hall effect. Interactions do not play a major role in this context. On the other hand, topological order is a notion proposed by X.-G. Wen that takes its origin in the fractional quantum Hall effect, which crucially depends on interactions between electrons. A topologically-ordered system is characterized by a robust ground-state degeneracy that depends on the genus of the surface on which the system is placed (whether a sphere or a torus, for example) and it features fractionalized quasiparticles known as anyons. Important aspects are long-range quantum entanglement and the non-local nature of the order.

Mardi 12 Novembre 2024, 14:00 à LPENS, L378, 24 Rue Lhomond	LPTENS-HE (Séminaire commun LPTENS-LPTHE)	hep-th
Daniele Artico ( Humboldt Universitaet Berlin )	TBA
Abstract:	TBA

Mercredi 13 Novembre 2024, 13:30 à DPT-PHYS-ENS, salle ConfIV (Département de Physique de l'ENS - 24 rue Lhomond 75005 PARIS)	COLLOQUIUM-ENS (Colloquium of the Physics Department of ENS)	physics
David Tong ( University of Cambridge )	TBA
Abstract:	Relativistic fermions split into a two distinct pieces, usually referred to as “left-handed” and “right-handed”. One of the great discoveries of the 20th century is that fermions with a different handedness experience different forces. This chiral nature of our universe gives rise to many puzzles, from how to construct discrete versions of the laws of physics through to questions of particle scattering. I’ll review some of these puzzles and describe recent progress in addressing them.

Jeudi 14 Novembre 2024, 14:00 à LPTMC, Jussieu, LPTMC seminar room, towers 13-12, 5th floor, room 523	SEM-LPTMC (Séminaire du Laboratoire de Physique Théorique de la Matière Condensée)	cond-mat
Pascal Simon ( LPS Orsay )	Hund's assisted multi-channel quantum phase transition in an iron superconductor
Abstract:	Understanding the interplay between individual magnetic impurities and superconductivity is crucial for bottom-up construction of novel phases of matter, as well as to exploit the local response as a probing tool. For decades, the description by Yu, Shiba and Rusinov (YSR) of single spins in a superconductor and its extension to include quantum effects has proven highly successful: the pair-breaking potential of the spin generates sub-gap bound states. I will first show how atomically-resolved shot noise can be used to reveal the coherent and incoherent dynamics of such sub-gap bound states [1]. By tuning the energy of the sub-gap states through zero, the impurity screening by the superconductor makes the ground state gain or lose an electron, signalling a parity breaking quantum phase transition. I will present a set of scanning tunneling microscopy (STM) measurements that explicitly invalidate the classical YSR paradigm, and propose an interpretation in terms of a multi-orbital Anderson impurity model [2]. In particular, I show that in multi-orbital impurities, electronic correlations can conversely lead to a quantum phase transition where the impurity mean occupation changes dramatically, without significant effect of the screening by the superconductor. This finding implies that the YSR treatment is not always valid, and that intra-atomic interactions, particularly Hund’s coupling that favours high-spin configurations, are an essential ingredient for understanding the sub-gap states. [1] U. Thupakula, V. Perrin, A. Palacio-Morales, L. Cario, M. Aprili, P. Simon, F. Massee, Phys. Rev. Lett. 128, 247001 (2022) [2] M. Uldemolins, A. Mesaros, G. D. Gu, A. Palacio-Morales, M. Aprili, P. Simon, and F. Massee, “Interaction- driven quantum phase transition of a single magnetic impurity in Fe(Se,Te)” 2023, arXiv:2310.06030.

Lundi 18 Novembre 2024, 14:00 à LPNHE, Salle des seminaires (1222-RC/SB-08)	LPNHE (Séminaires du LPNHE)	physics
Ulisses Barres De Almeida ( University of Durham )	The Southern Wide-Field Gamma-ray Observatory (SWGO)
Abstract:	SWGO is an international proposal to build a wide-field observatory to explore the Southern Hemisphere sky in the energy range of a few hundred GeV to the PeV. Its objective is to open a new window of astronomical observation, in a field where observational coverage is currently limited to the northern hemisphere, through the HAWC and LHAASO observatories. SWGO will be installed in the Atacama Astronomical Park, in the Chilean Andes, at an altitude of 4,770 m above sea level, and will be based on an array of Cherenkov water detectors deployed over an area of 1 km2. In this presentation I will present an overview of the SWGO proposal and future plans for this instrument, as well as its financing and construction prospects, and scientific objectives.

Mardi 19 Novembre 2024, 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
Chunxiao Liu ( Berkeley )	TBA

Mercredi 20 Novembre 2024, 11:00 à LKB, Sorbonne Université - 4 places Jussieu 75005 - Amphi Charpak	SEM-LKB (Séminaire du Laboratoire Kastler Brossel)	quant-ph
Yvonne Gao ( National University of Singapore. )	Quantum information processing via on-demand light-matter interaction
Abstract:	The diverse applications of light-matter interactions in science and technology stem from the qualitatively distinct ways these interactions manifest. I will present a series of experimental work that employs the light field of high-Q superconducting cavities coupled to non-linear circuit elements to harness the rich dynamics of their interactions for quantum information processing. With these versatile bosonic cQED systems, we show the ability to create, manipulate, and characterise complex non-Gaussian resource states and achieve loss protection for them through phase-space engineering. Moreover, by incorporating frequency-tunablility in our devices, we can effectively probe the intersections of different light-matter interaction regimes on demand. Our work shows that bosonic cQED systems, albeit small in scale, provide a powerful platform to explore quantum information science and applications.

Jeudi 21 Novembre 2024, 11:00 à IHES, Amphithéâtre Léon Motchane ( Séminaire de Géométrie Arithmétique )	MATH-IHES (TBA)	math
Johannes Anschuetz ( Paris-Saclay et IHES )	Pro-étale Cohomology in p-adic Geometry
Abstract:	Pro-étale cohomology of rigid-analytic varieties over the p-adic complex numbers has surprising features, which can be explained by calculating the pro-étale cohomology via quasi-coherent sheaves on the Fargues-Fontaine curve. In this talk I want to explain the recent construction of a 6-functor formalism with values in quasi-coherent sheaves on the Fargues-Fontaine curve, and to discuss some of its properties. This is joint work with Arthur-César Le Bras and Lucas Mann.

Jeudi 21 Novembre 2024, 14:00 à LPTMC, campus Jussieu, couloir 12-13, 5ème étage, salle 5-23	SEM-EXCEP (Seminaire exceptionnel)	cond-mat
Francesco Mori ( Oxford )	TBA

Mardi 26 Novembre 2024, 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
Marcelo Guzmán ( Université de Pennsylvanie )	TBA

Mardi 26 Novembre 2024, 14:00 à LPENS, L378, 24 Rue Lhomond	LPTENS-HE (Séminaire commun LPTENS-LPTHE)	hep-th
Nika Sokolova ( King's College London )	TBA
Abstract:	TBA