Seminar on Disorder and strong electron correlations: "Ultracold atoms in optical lattices: Beyond the Hubbard model"
Starts 26 Apr 2012 12:30
Ends 26 Apr 2012 20:00
Central European Time
Leonardo da Vinci Building Luigi Stasi Seminar Room
Strada Costiera, 11
I - 34151 Trieste (Italy)
We investigate the properties of ultra-cold atomic gases in optical lattices, which we use as a toy-system to explore the intriguing properties of strongly correlated quantum many-body systems in periodic potentials.
In this work, we address the regime of weak and intermediate optical lattices, where the conventional description in terms of the single band Hubbard model is not reliable.
In the case of bosonic atoms, we employ a novel hybrid Monte Carlo technique which allows to simulate the superfluid to insulator transition in continuous space, thus going beyond the single-band approximation. For fermions, we apply Kohn-Sham Density Functional Theory (DFT), which is the most powerful computational tool routinely used in material science to perform electronic structure simulations. In this work, we use a new
energy-density functional for dilute atomic Fermi gases with short-range interactions, as opposed to the Coulomb interaction in electronic systems. The first results based on a local spin-density approximation show evidence of a ferromagnetic phase due to the strong repulsive inter-species interactions close to a Feshbach resonance, and of anti-ferromagnetic order at half filling.
We will discuss how the development of DFT for ultracold Fermi gases can form a strong link between materials science and atomic physics.