Agenda depuis 2025
Seminaire : Séminaire CANA : Nasra Daher Ahmed
04/03/2025 à 14h00
Title Introduction to quantum information theorySalle : 04.05 TPR2
Abstract :
Quantum information (QI) theory studies the ways the laws of quantum mechanics allow the storage, processing and transmission of information. Its most well-known applications are the fields of quantum computing, communication and key distribution. However, it also has applications in other fields of physics such as condensed matter and gravitation physics.
This introductory seminar aims to give the basic tools needed to understand current research in quantum information theory and its applications. First, we review some basic concepts of classical information theory and the mathematical formalism of quantum mechanics. We will then introduce some important topics in QI such as entanglement, nonlocality and no-go theorems about the manipulation of quantum information.
Seminaire : Séminaire CANA : Ugo Nzongani
25/02/2025 à 14h00
Title : Introduction to Quantum ComputingSalle : 04.05 TPR2
Abstract :
Quantum computing leverages the principles of quantum mechanics to develop algorithms that, in some cases, significantly outperform their classical counterparts. In this seminar, we will introduce the fundamental building blocks of quantum computation, including qubits, quantum gates, and quantum circuits. We will then briefly discuss key quantum algorithms such as Shor’s algorithm for factoring, Grover’s search algorithm, and variational methods for optimization (QAOA). Additionally, we will provide a detailed explanation of how the Deutsch-Jozsa algorithm offers an exponential speedup over classical approaches.
Seminaire : Séminaire ACRO : Nicolas Trotignon
10/02/2025 à 10h00
Nicolas Trotignon (ENS Lyon) Title: A survey of layered wheels 10/02/2025 10h00, salle REU 04.05 (LIS Luminy) Layered wheels are constructions of graphs first discovered by Ni Luh Dewi Sintiari and the speaker. They disprove several conjectures and answer several questions. For instance, jointly with Maria Chudnovsky, the speaker could use them to disprove a conjecture de Dallard, Milanič and Štorgel about the tree-independence number and a conjecture of Hajebi about the induced subgraphs contained in graphs of high treewidth. The goal of the talk is to present all the situations where layered wheels turned out to be useful and to present in more details the variant that disproved the two conjectures mentioned above.Seminaire : Séminaire I&M - DE SOUSA SILVA, Raul Alfredo
31/01/2025 à 14h00
Titre : Modélisation du comportement complexe autistique chez la souris en utilisant des approches d'apprentissage profonde et vision par ordinateurLieu : Luminy, TPR2 salle de réunion 04.03.
Résumé :
Le Trouble du Spectre Autistique (TSA) est une trouble neurodéveloppemental qui se caractérise par un déficit de communication et interaction sociale ainsi que par des comportements répétitifs et des intérêts restreints. Les souris sont des animaux sociaux et sensibles comme nous, c’est justement à cause de ce comportement social que l’on étudie les souris pour mieux comprendre l’autisme chez l’humain. Dans le cadre de ce projet, nous visons retrouver des séquences de comportement qui distinguent une souris contrôle d'une souris modèle à l'aide des algorithmes d'apprentissage profond et vision par ordinateur. Pendant la dernière année, nous avons fait plusieurs progrès dans l'amélioration de la détection de certaines actions, de la gestion des données bruitées et de la création des protocoles analytiques permettant de sortir des informations pertinentes à propos des souris. Je vous présenterai en détail ces avancées, les justificatifs méthodologiques et les prochains pas vers l'achèvement de ce projet.
Seminaire : Séminaire ACRO : Simon Vilmin (27/01, 10h00, REU 4.05)
27/01/2025 à 10h00
Simon Vilmin (LIS, Aix-Marseille Université) Title: Enumerating the minimal keys of an implicational base 27/01/2025 10h00, salle REU 04.05 (LIS Luminy) An implicational base (IB) over a groundset X is a collection of statements A --> B, called implications, where A and B are subsets of X. An IB induces a convexity space where a set C is convex if it satisfies each implication A --> B of the IB: if C includes A, it includes B. The convex hull of a subset S of X is the inclusion-wise minimal convex set including S. A key is a subset K of X whose convex hull is X, i.e. a generating set of X. In this talk, we will discuss the following problem: enumerate all the minimal keys of a convexity space given by an IB. This problem has notably been studied within the context of database theory, from which the term "key" originates and where implications are better known as "functional dependencies". It also relates to the enumeration of prime implications of a pure Horn CNF, and can be seen as a generalization of the problem of enumerating minimal hull sets---an other name for minimal keys---of (binary) graph convexities. I will present the result of Lucchesi and Osborn 78 that gives a polynomial-delay algorithm listing all minimal keys associated to an IB. Their algorithm implicitly uses solution-graph traversal to solve the problem. I will also present an alternative proof of their result using elements from the framework of proximity search.Seminaire : Séminaire CANA : Nicolas Schabanel
21/01/2025 à 14h00
Title : How do we make DNA origami and what are the challenges we tackle Nicolas SchabanelJoint work with: Nicolas Levy (LIP), Julie Finkel (CBS), Allan Mills (CBS), Pierre Marcus (LIP), Octave Hazard (LIP), Daria Pchelina (LIP), Joris Picot (LIP) and Gaëtan Bellot (CBS)
Salle : 04.05 TPR2
Abstract :
Curved shapes are ubiquitous in both natural and engineered structures contributing to their intricate functionalities and mechanical resilience. Replicating these shapes at the nanoscale using DNA nanotechnology poses significant challenges due to the inherent constraints of DNA geometry. Here, we introduce a geometric model for curved DNA helices and an algorithm for automatic routing of DNA helices along non-planar trajectories to fold predefined 3D DNA origami nanostructures. We provide an automated design process that enables the self-assembly of curved DNA helix bundles, hollow shapes, nested spheres, and biomimetic structures such as vault-like cages, using a novel spiral-based paradigm. This process, integrated in ENSnano software, revisites DNA origami principles to go beyond current structural confinements and opens opportunities for creating general 3D spatial configurations with advanced programmability for enhanced functional integration. L’exposé sera spécialement conçu pour des personnes qui ne connaissent rien du tout à l’ADN ni au origami ADN.
Seminaire : Séminaire cybersécurité : Privacy-Preserving Data Processing at Scale: How Much Can You Trust Your Cloud Provider?
21/01/2025 à 10h30
Séminaire cybersécurité : le mardi 21/01 à 10h30 en salle 4.05 TPR2 LuminySpeaker: Pascal Felber, Université de Neuchâtel
Title : ’‘ Privacy-Preserving Data Processing at Scale: How Much Can You Trust Your Cloud Provider?’‘
Abstract : The processing of large amounts of data requires significant computing power and scalable architectures. This trend makes the use of Cloud computing and off-premises data centres particularly attractive but exposes companies to the risk of data theft. This is a key challenge toward outsourcing data processing to external Cloud providers, as data represents for many companies their most valuable asset. In this talk, we will discuss recent and emerging mechanisms to support privacy-preserving data processing, i.e., confidential computing, on untrusted architectures.
Seminaire : Séminaire ACRO : Guilherme Gomes (20/01, 14h00, REU 4.05)
20/01/2025 à 14h00
Guilherme Gomes (Federal University of Minas Gerais, Brasil) Title: Matching Multicut: Parameterized Complexity and Enumeration 20/01/2025 14h00, salle REU 04.05 (LIS Luminy) The Matching Cut problem asks if a graph admits a partition of its vertex set in two such that no vertex has more than one neighbor across the cut. This problem has drawn considerable attention of the algorithms and complexity community in the last decade, becoming a canonical example for parameterized enumeration algorithms and kernelization. In this talk, we discuss one of its generalizations: Matching Multicut - can we partition the vertex set of a graph in at least ℓ parts such that no vertex has more than one neighbor outside its part? In particular, we will present some results on cubic graphs and more generally on parameterized complexity, the latter focused on enumeration kernelization. Joint work with Emanuel Juliano, Gabriel Martins, and Vinicius Santos.Seminaire : Séminaire ACRO : Florian Galliot (13/01/2025, 10h00, REU 4.05)
13/01/2025 à 10h00
Florian Galliot (I2M, Aix-Marseille Université) Title: Graph reconstruction from queries on triples 13/01/2025 10h00, salle REU 04.05 (LIS Luminy) We consider the problem of reconstructing a graph G from a query Q which, for every k-subset of vertices S, provides some information Q(G)(S) about the induced subgraph G[S]. The vertices are labelled from 1 to n, so reconstruction up to isomorphism is not sufficient, we need to know which label is where. We have studied the case k=3. Given a query Q on triples, we are interested in two things: a structural characterization of all graphs G that are uniquely reconstructible from the function Q(G) (i.e. such that Q(H)=Q(G) if and only if H=G), and a polynomial-delay enumeration algorithm of all graphs that are consistent with some input query answers. In 2023, Qi and Bastide et al. respectively have managed this for the connectivity query (meaning that, for every triple S, Q(G)(S) indicates whether G[S] is connected). We have obtained the same results for all 13 other non-trivial queries on triples. This presentation will go into details of a select few of these queries. Joint work with Hoang La, Raphaëlle Maistre, Matthieu Petiteau and Dimitri Watel.Seminaire : Séminaire CANA : Antoine Soulas
07/01/2025 à 14h00
Title : Quantifying quantum coherence and the deviation from the total probability formulaSalle : 04.05 TPR2
Abstract :
Quantum coherence is the main resource exploited by quantum computers. Unsurprisingly, over the past few years, there has been a strong interest in the task of finding appropriate measures of coherence. In this talk, we propose a novel approach to quantify quantum coherence which, contrary to the previous ones, does not rely on resource theory but rather on ontological considerations. In this framework, coherence is understood as the ability for a quantum system's statistics to deviate from the total probability formula (TPF). After a recap on the basics of quantum theory, we motivate the importance of the TPF in quantum foundations. We then propose a new set of axioms that a measure of coherence should satisfy, and show that it defines a class of measures different from the main previous proposal. Finally, we prove a general result about the dependence of the l2-coherence norm on the basis of interest, namely that it is well approximated by the square root of the purity in most bases. Such a behaviour is actually expected for any measure of coherence, because of the mathematical phenomenon known as « concentration of measure ».