UFR de Physique

Propositions de stages en laboratoire -- M2

Les offres sont actualisées en mai. Par exemple, les offres de stages pour l'année universitaire 2015-2016 seront mises en place en mai 2015, les offres de stages pour l'année universitaire 2016-2017 seront mises en place pour en mai 2016, etc.

Time crystals in the interacting quantum kicked rotor

  • Option Lumière-Matière, Générique du parcours Lumière-Matière
  • Laboratoire: Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM)
  • Responsable du stage: Rançon Adam (adam.rancon@univ-lille1.fr, 03.20.43.69.86)
  • Mots clés: Time-crystals, disordered systems, cold atoms
  • Fiche complète en PDF : Fiche complète en PDF

The interplay between interactions and disorder is one of the most challenging problems in physics. For non-interacting quantum particles, it can induce Anderson localization, depending on both the energy of the particle and on the dimension of the system. Naively, one would expect that repulsive interactions in presence of disorder would tend to delocalize the system. However, it has been demonstrated recently, both on the theoretical and experimental level, that interactions in addition to disorder give rise to a new phase of matter, the so-called many-body localized phase, in which the whole many-body system can be localized, and cannot thermalize if isolated from a thermal bath. While disorder takes place in space, it is also possible to perturb the system in time. By itself, the dynamics of a quantum interacting system represents a complicated problem, which gets even more subtle in presence of disorder. In much the same way as an ensemble of particles can spontaneously order to form a crystal, and thus breaks translation invariance, the idea of a time-crystal, which breaks spontaneously time-translation invariance, has been introduced recently. The basic ingredients for a time-crystal are not yet clear, while it seems that long-range interactions and disorder can help to stabilize this out-of-equilibrium phase. The recent experimental realizations of both many-body localized systems and time-crystals have opened an exciting horizon which challenges our understanding of quantum statistical physics. A promising system for the observation of time-crystals and many-body localization is the interacting quantum kicked rotor, which is a model of interacting bosons driven periodically, with properties similar to disordered systems. A cold atom experiment is currently being built in the laboratory by the Cold Atoms Team to study this system. A better theoretical understanding of this model, and the possible phases (delocalized/many-body localized/ime-crystal) is therefore necessary, which is the purpose of the internship. This will be done by studying various models, and combining both analytical and numerical methods.