Agenda depuis 2025

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 Schabanel
Joint 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 Luminy

Speaker: 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 formula

Salle : 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 ».