Centre de Physique Théorique


April 2018

Wednesday 4 April 14:00-15:00, CPT, Amphi 5


Vojkan Jaksic (Department of Mathematics and Statistics, McGill University, Canada)



Thursday 5 April 14:00-15:00, Amphi 5 du CPT

Séminaire de Physique Statistique & Matière Condensée

Alexis Dubreuil (ENS, Paris)

Titre: A sensory-motor hub driving photo-taxis in zebrafish

Résumé: Animals continuously gather sensory cues in order to move towards favorable environments. Efficient goal-directed navigation requires sensory perception and motor command to be intertwined in a feedback loop, yet the neural substrate underlying this sensorimotor task in the vertebrate brain remains elusive. Here we present analysis of whole-brain calcium recordings together with circuit modeling to reveal the neural mechanisms through which zebrafish performs phototaxis, i.e. actively orients towards a light source. Key to this process is a self-oscillating hindbrain network that acts as a pacemaker for ocular saccades and controls the orientation of successive swim-bouts. It further integrates visual stimuli in a state dependent manner, i.e. its response to visual inputs varies with the motor context, a mechanism that manifests itself in the phase-locked entrainment of the circuit by periodic stimuli. A rate model is developed that reproduces our observations and demonstrates how this sensorimotor processing eventually biases the animal trajectory towards bright regions.

Friday 6 April 14:00-15:00, Amphi 5 du CPT


Karim Noui (Tours)

Wednesday 11 April 14:00-15:00, CPT, Amphi 5


Julien Sabin (Département de Mathématiques, Université Paris-Sud)

Wednesday 11 April 15:30-17:00, CPT, Amphi 5

Quantum measurements and simulation with Rydberg atoms

Jean-Michel Raimond Sorbonne Université, Paris Laboratoire Kastler Brossel, Collège de France, ENS, CNRS

The exploration of the puzzling features of the quantum, like state superpositions, entanglement or measurement processes is a thriving experimental field. It is driven by fascinating applications of the quantum, like quantum metrology, quantum information processing or quantum simulation.
Rydberg atoms, long-lived and extremely strongly coupled to external fields, are ideal tools to explore these basic quantum features. We will review a few explorations of the quantum performed at Collège de France using these remarkable states.
The strong interaction of circular Rydberg states with microwave fields in high quality superconducting cavities lead to ideal measurements of the photon number, illustrating all postulate of quantum measurement, or to the generation of field states reminiscent of the famous Schrödinger cat. Coherent manipulations in the complex Rydberg manifold lead to the observation of quantum Zeno dynamics and to the realization of ultra-sensitive electric field measurements. Finally, we will present a quantum simulator project emulating spin chains with laser-trapped circular Rydberg atoms.

From 24 to 25 April, Université de Toulon

Conference Semi-classical and Geometric Asymptotics in Mathematical physics

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Cette Conférence est organisée dans le cadre d’un Projet International de Coopération scientifique (PICS) avec la Russie, avec comme partenaires, d’une part le Centre de Physique Théorique (UMR 7332, Université d’Aix-Marseille, Université de Toulon, CNRS) ; d’autre part le Centre Interdisciplinaire J.-V. Porcelet (UMI CNRS, Moscou), et l’Institut Ishlinski pour les Problèmes de la Mécanique (Moscou).