Description du sujet de thèse

Advances in the cooling and manipulation of atomic gases over the past few decades have provided full access to the quantum world. Quantum degeneracy has been achieved for both fermions and bosons, and Bose-Einstein condensation has been observed experimentally by cooling atomic gases to a few tens of nK. These ultracold gases can be confined not only in three dimensions, but also in two and one dimensions. Lowering the dimensionality has the effect of increasing correlations between atoms.

Amazing phenomena can occur for quantum particles living in one dimension: for example, the effect of interactions is exacerbated by decreasing the density of atoms, and strongly interacting bosons behave like free fermions. One-dimensional quantum mixtures offer the privilege of accessing, in certain cases, the exact many-body wave function. A special case that allows for further computational progress, capturing correlation functions and dynamics even in the presence of external confinements, is the Tonks-Girardeau limit, where the contact interaction between particles is repulsive and tends to infinity. The study of this limiting case provides a deep understanding of quantum correlations in many-body systems, both at equilibrium and out of equilibrium, and provides a benchmark for classical and quantum simulators of these systems.

This thesis will focus on the dynamics of ultracold one-dimensional mixtures in the strong interaction regime, where exact solutions can be obtained. Particular attention will be paid to situations where the dynamics is extremely slow, for example, in the presence of disorder or localization mechanisms through interference effects. In these regimes, the timescales required to explore the dynamics can exceed the experimental lifetime of the systems, making their direct observation difficult.

To overcome this limitation, we will develop protocols to accelerate the time evolution of these quantum systems without modifying their physical content. These methods, which can be grouped under the term "shortcuts to dynamics" aim to quickly access the properties of interest during a long evolution in a controlled manner, by exploiting the structure of the state space. Similar to a "next chapter" button in a video player, the goal is to jump into the dynamic future of a system while respecting its natural evolution.

This work lies at the interface of theoretical quantum gas physics, non-equilibrium physics, and quantum control. It will benefit from strong interaction with current experimental developments and advances in numerical simulation and analytical calculations.

Contexte de travail

The INPHYNI laboratory, headed by Guillaume Huyet, is located in Nice. The laboratory conducts numerous research activities focused on waves, quantum physics, photonics, nonlinear physics, complex fluids, and biophysics. The candidate will work in the laboratory's Theoretical Physics team, headed by Frédéric Hébert, and as part of the PEPR Dyn1D project.

Le poste se situe dans un secteur relevant de la protection du potentiel scientifique et technique (PPST), et nécessite donc, conformément à la réglementation, que votre arrivée soit autorisée par l'autorité compétente du MESR.

Contraintes et risques

Constraints: The thesis will be completed primarily in person, in collaboration with the two thesis supervisors.

Risks: None