PhD Opportunities (Archived)

PhD Position: ULTRACOLD 1D FERMI GASES at the ENS Paris

A 3 year PhD scholarship and a 2 year postdoc position are open at LKB ENS on the physics of 1D Fermi gases.

Quantum physics in lower dimension is strikingly different from its 3D counterparts, and many paradigms governing three-dimensional phenomena fail when the dynamics of particles is confined in one or two dimensions. A celebrated example is the breakdown of Landau’s Fermi liquid model in 1D: while thermodynamical and transport properties of 3D interacting fermionic systems can be captured by assuming that they behave as an ensemble of weakly interacting quasi-particles, the low-lying excitations of one-dimensional systems are governed by collective excitations where density and spin degrees of freedom are decoupled and are described by a so-called Luttinger-Tomonaga Liquid.

This project is devoted to the experimental study of strongly correlated ultracold Fermi gases trapped in an optical lattice confining the atoms in tubes where their dynamics is (quasi) one- dimensional (see figure below). Using the unique possibilities offered by ultracold atoms, we will explore the crossover between the 3D and 1D regimes. We will investigate the fate of superfluidity by probing the response of the system to a moving perturbation and we will characterize the role of interactions in the crossover. In particular virtual transitions towards the excited states of the trapping potential break the pure 1D character of the system and lead to a hybrid dimensional regime where powerful theoretical methods developed for the study of 1D systems are no longer applicable. In this intermediate regime combining strong correlations and low dimensionality, our setup will play the role of a quantum simulator that will be used to benchmark the novel theoretical approaches required to understand this peculiar system.

Figure 1: array of individual 1D tubes. The distance between two neighboring tubes is 2.5μm and each tube contains typically a hundred atoms. Figure from de Daniloff et al., arXiv:2102.01589.

The project will be conducted in collaboration with Amandine Aftalion at EHESS and the theory team of Giuliano Orso at MPQ.

Interested candidates should contact and address a CV to Frédéric Chevy (frederic.chevy@ens.fr)page1image19108160