STAGE Testing QED and gravity interactions with an ultracold atomic quantum sensor

Date de mise à jour de l’offre

SYRTE, SYstèmes de Référence Temps-Espace :

Situé à l’Observatoire de Paris, le SYRTE - Systèmes de Référence Temps-Espace - est une unité mixte de recherche (UMR 8630) du CNRS, de l’Observatoire de Paris - Université PSL et de Sorbonne Université. Alliant recherche de très haut niveau et services scientifiques, le SYRTE se place aujourd’hui au premier rang international dans des champs disciplinaires variés : métrologie du temps et des fréquences, systèmes de référence célestes, rotation de la Terre, histoire de l’astronomie. La pluridisciplinarité du SYRTE se retrouve aussi dans ses compétences transverses - théorie, instrumentation, traitement et analyse de données - et dans la diversité de ses objectifs qui vont de la physique fondamentale jusqu’au transfert industriel.

Description de la mission

The aim of our project is to realize precise measurements of atom surface interactions, in order to test QED and gravity related interactions. We expect to test predictions of underlying theories at distances of order of a µm, and push limits on possible deviations from them. The sensitivity of our atom interferometer sensor will allow improving current limits on tests of gravity at short distances, with a new technique, completely different from “classical experiments that use macroscopic bodies.

In our experiment, cold atoms are trapped in a vertical lattice, and an atom interferometer is used to measure the force experienced by the atoms. The interferometer is created by putting the atoms in a quantum superposition of wavepackets localized in two neighboring wells thanks to laser pulses, and letting them evolve, before recombining them. The phase difference accumulated by the two partial wavepackets, proportional to the energy difference between the wells, reveals among over quantities, the atom-surface interaction. As a first step, we measured the Bloch frequency, corresponding to the gravitational energy difference between adjacent wells, with a 10-7 resolution using a Ramsey type interferometer and atoms far from the surface. This resolution will allow to measure Casimir Polder forces between the atoms and the surface of the mirror with an uncertainty more than one order of magnitude better than state of the art. More recently, we have studied the influence of atomic interactions in a dense ultracold atomic sample onto the coherence time of our interferometer and put into evidence unexpected competition between two synchronization mechanisms, based on spin echo techniques and self-spin rephasing due to the identical spin rotation effect. A good control and understanding of such interactions is a prerequisite for the success of the project.

The aim of this internship consists in realizing force measurements in the vicinity of a mirror placed under vacuum, with ultracold atoms transported close to its surface before being interrogated. The work will focus on optimizing the transport efficiency, the control of the final atoms position, and the loading of the lattice trap. Once loaded in the trap at controlled distances from the surface, first short range force measurements will be carried out.

Profil recherché

Master de physique, spécialité interaction matière rayonnement

Niveau de qualification requis

Bac + 4/5 et +
  • Employeur
    SYRTE, SYstèmes de Référence Temps-Espace
  • Secteur d’activité de la structure
    Enseignement - Formation - Recherche
  • Effectif de la structure
    De 51 à 250 salariés
  • Site internet de la structure
    https://syrte.obspm.fr
  • Type de stage ou contrat
    Stage pour lycéens et étudiants en formation initiale
  • Date prévisionnelle de démarrage
  • Durée du stage ou contrat
    Plus de 4 mois et jusqu'à 6 mois
  • Le stage est-il rémunéré ?
    Oui
  • Niveau de qualification requis

    Bac + 4/5 et +
  • Lieu du stage
    Observatoire de Paris, 61 av de l’Observatoire
    75014 PARIS 14E ARRONDISSEMENT
  • Accès et transports
    RER métro Denfert Rochereau