2018-2019 ICFP seminar Program

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Retrouvez toutes les informations pour vos stages :
Stages L3
Stages M1 ICFP
Stages M2 ICFP

Actualités : Séminaire de Recherche ICFP
du 6 au 10 novembre 2017 :

Retrouvez le programme complet

Emploi du temps 2017-2018 :
Emploi du temps L3
Emploi du temps M1 ICFP
Emploi du temps M2 ICFP

Contact - Secrétariat de l’enseignement :
Tél : 01 44 32 35 60
enseignement@phys.ens.fr

The seminar takes place on Tuesday, at 5:15pm.

 September 25 : Arnaud Landragin

LNE-SYRTE, Observatoire de Paris
Atom interferometry for high sensitivity in inertial measurements

Atom interferometry is based on the wave-matter duality principle, stated by Louis de Broglie. In practice, most of the atom interferometers are based on the manipulation of the atomic wave-packets (splitting, deflection) by light. Since the pioneering experiments of 1991, atom interferometry has established as a unique tool for precision measurements of fundamental constants and of gravito- inertial effects. Atom interferometry covers multiple applications in metrology, inertial navigation, geophysics, tests of fundamental physics, and has been proposed for gravitational wave detection. Indeed, atom interferometry combines both intrinsic high sensitivity and accuracy thanks to the high level of control of the atom-laser interaction. Two main classes of interferometers are studies : interferometers with atoms in free fall, which already achieve state of the art performances, and interferometers trapped or guided atoms, more prospective and opening for new applications. I will illustrate theses developments through different projects we are carrying.

 October 9 : M1 interships

Oral defenses of two M1 internships

Joris Verstraten
Laser system for quantum gas microscopy of ultracold molecules
MIT, USA

Paul Robin
Rotating paint catenaries : investigating a technique used by Jackson Pollock
Cambridge University, UK

 November 6 : Thomas Gregor

Institut Pasteur
Physics problems in early embryonic development

One of the most beautiful phenomena in nature is the emergence of a fully formed, highly structured organism from a single undifferentiated cell, the fertilized egg. Over the past decades, biologists have shown that in many cases the "blueprint" for the body is laid out with surprising speed and is readable as variations in the concentration of particular molecules (the “expression levels” of particular genes). In the fruit fly, we know the identity of essentially all the relevant molecules. As we try to understand how these molecules interact to form the patterns that we recognize as characteristic of the mature organism, we face a number of physics problems :

How can spatial patterns in the concentration of these molecules scale with the size of the egg, so that organisms of different sizes have similar proportions ? What insures that the spatial patterns are reproducible from one embryo to the next ? Since the concentrations of all the relevant molecules are small, does the random behavior of individual molecules set a limit to the precision with which patterns can be constructed ?

Although the phenomena of life are beautiful, one might worry that these systems are just too complicated and messy to yield to the physicists’ desire for explanation in terms of powerful general principles. For the past several years, a small group of us have been struggling with these problems in the context of the fruit fly embryo. To our delight, we have been able to banish much of the messiness, and to reveal some remarkably precise and reproducible phenomena. In particular, the first crucial step in the construction of the blueprint really does involve the detection of concentration differences so small that they are close to the physical limits set by the random arrival of individual molecules at their targets. This problem may be so serious that the whole system for constructing the blueprint has to be tuned to maximize how much signal can be transmitted against the inevitable background of noise, and this idea of tuning or optimization can be turned into a precise theoretical principle from which we can actually predict some aspects of how the system works. Parallel questions of noise, reproducibility and information transmission arise in many different biological systems.

 November 20 : Clément Sayrin

Laboratoire Kastler Brossel, Collège de France
Circular Rydberg Levels : Giant Atoms for Quantum Simulations
The dynamics of a quantum system, particularly in condensed matter, can be utterly complex, due to the huge size of the Hilbert space. Quantum simulation aims at emulating this dynamics on a simpler system, of which all parameters are under control and on which all relevant observables can be measured. We propose to realise such a quantum simulator with cold atoms prepared in highly excited levels, namely circular Rydberg atoms. In this talk, I will show how these giant atoms can be used to efficiently emulate interacting spin-1/2 systems. The atoms can be laser-trapped and protected from spontaneous-emission, thereby reaching lifetimes in the minute range. It will allow for the investigation of phenomena beyond the reach of current (classical) computers.

 December 4 : Jean-Philippe Bouchaud

Capital Fund Management
De la physique statistique aux sciences sociales
Comme l’écrivait presque en ces termes P. W. Anderson en 1972 dans « More is different », le comportement de grandes assemblées d’individus ne peut pas être compris à partir de l’extrapolation du comportement d’individus isolés. Au contraire, des comportements complètement nouveaux, parfois spectaculaires et difficiles à anticiper, peuvent apparaître et nécessitent des idées et des méthodes nouvelles. L’objet de la physique statistique est précisément de tenter de comprendre ces phénomènes collectifs, qui n’appartiennent à aucun des constituants élémentaires sous-jacents. En particulier, de petits changements au niveau individuel peuvent entraîner des effets dramatiques au niveau collectif. Plusieurs exemples simples seront discutés, qui démontrent la nécessité (et la difficulté) d’aller au-delà des modèles de l’économie classique, basés sur l’idée d’un « agent représentatif ». Quelques pistes récentes seront évoquées.

 December 18 : Bruno Andreotti

PMMH laboratory, ESPCI
Sand dune morphodynamics, from Earth to extra-terrestrial conditions
An erodible bed sheared by a fluid flow, gas or liquid, is generally unstable, and edforms grow. The following questions are discussed, in the light of the recent literature : What are the relevant dynamical mechanisms controling the emergence of bedforms ? Do they form by linear instability or nonlinear processes like pattern-coarsening ? What determines their time and length scales, so di fferent in air and water ? What are the similarities and di fferences between aeolian and subaqueous patterns ? What is the influence of the mode of transport : bedload, saltation or suspension ? Can bedforms emerge under any hydrodynamical regime, laminar and turbulent ? How can one classify bedforms on Mars, Venus, Titan or Pluto ? Guided by these questions, a unified description of bedform growth and saturation is proposed, with emphasis on the hydrodynamical regime in the inner layer and the relaxation phenomena associated with particle transport.

  January 15 : Takis Kontos

Laboratoire Pierre Aigrain, ENS Paris
Nanoélectronique hybride
Dans cet exposé, je montrerai comment des techniques de nano-assemblage de conducteurs nanométriques tels que des nanotubes de carbone permettent d’élaborer des puces où l’on peut faire interagir de manière contrôlée des électrons et des photons piégés. Ce type de nano-circuits présentent des comportements quantiques à très basse température et peuvent être utilisés pour l’information quantique avec des spins, pour étudier la matière topologique ou bien des systèmes de fermions en interaction. Mon exposé abordera ces 3 aspects en se focalisant sur les concepts généraux ainsi que les méthodes expérimentales.

Accès rapides

Prochain Séminaire de la FIP :
Accéder au programme

Retrouvez toutes les informations pour vos stages :
Stages L3
Stages M1 ICFP
Stages M2 ICFP

Actualités : Séminaire de Recherche ICFP
du 6 au 10 novembre 2017 :

Retrouvez le programme complet

Emploi du temps 2017-2018 :
Emploi du temps L3
Emploi du temps M1 ICFP
Emploi du temps M2 ICFP

Contact - Secrétariat de l’enseignement :
Tél : 01 44 32 35 60
enseignement@phys.ens.fr