Two-dimensional fermionic mixtures with dipolar interactions: A quantum Monte Carlo study
[Talk given at ENS-Lyon, on July 5th, 2018]Abstract: One of the interesting features of ultracold atomic gases is the possibility of exploring systems with different interatomic interactions. On top of the common short-ranged potentials, current experiments are often performed with atoms or molecules having a strong dipolar moment, which adds a longer-ranged part to the interactions.
We consider a system of fermionic dipoles confined in two dimensions and aligned in the transverse direction, such that their interaction is a repulsive power-law potential (1/r^3, as a function of the interparticle distance r). The ground-state properties of a uniform system are accessed through the diffusion quantum Monte Carlo technique.
In the low-density regime (the closest to current experiments with gases of erbium or dysprosium) we compute the equation of state of a two-species mixture, and study the properties of the extremely unbalanced case of a single impurity in a bath of the other species. At large density, we address the issue of itinerant ferromagnetism, namely the possibility for the ground state to have a non-zero polarization. This is a subtle many-body problem which was studied for several other systems (electrons, helium, short-ranged ultracold gases) and we show that a high-accuracy version of the quantum Monte Carlo technique is required to reach the correct conclusion.