We kindly invite to seminar in the framework of Modern Trends in Physics Research: Wednesday,** December 13, 2017** at 13:00 in room 16, Faculty of Physics AMU. Speaker: **Dr Agnieszka Cichy**. Affiliation: Solid State Theory Division, Faculty of Physics, AMU. Title: **Classical and quantum simulations with ultracold 4-component fermionic mixtures in optical lattices**.

Abstract:

The impressive development of experimental techniques in ultracold quantum degenerate gases of alkaline-earth-like atoms in the last years has allowed investigation of strongly correlated systems. Long-lived metastable electronic states in combination with decoupled nuclear spin give the opportunity to study the Hamiltonians beyond the possibilities of current alkali-based experiments. Ytterbium is particularly convenient due to its large number of bosonic and fermionic (e.g. Yb-173) isotopes with a wide range of interaction strengths. In [1] we study finite-temperature properties of ultracold four-component mixtures of alkaline-earth-metal-like atoms in optical lattices that can be effectively described by the two-band spin-1/2 Hubbard model including Hund's exchange coupling term. Our main goal is to investigate the effect of exchange interactions on finite-temperature magnetic phases for a wide range of lattice fillings. We use the dynamical mean-field theory approach and its real-space generalization to obtain finite-temperature phase diagrams including transitions to magnetically ordered phases. It allows to determine optimal experimental regimes for approaching long-range ferromagnetic ordering in ultracold gases. We also calculate the entropy in the vicinity of magnetically ordered phases, which provides quantitative predictions for ongoing and future experiments aiming at approaching and studying long-range ordered states in optical lattices. In [2] we study the thermodynamic properties of four-component fermionic mixtures described by the Hubbard model using the dynamical mean-field-theory approach. Special attention is given to the system with SU(4)-symmetric interactions at half filling, where we analyze equilibrium many-body phases and their coexistence regions at nonzero temperature for the case of simple cubic lattice geometry. We also determine the evolution of observables in low-temperature phases while lowering the symmetry of the Hamiltonian towards the two-band Hubbard model. This is achieved by varying interflavor interactions or by introducing the spin-flip term (Hund's coupling). By calculating the entropy for different symmetries of the model, we determine the optimal regimes for approaching the studied phases in experiments with ultracold alkali and alkaline-earth-like atoms in optical lattices.

[1] A. Cichy, A. Sotnikov, Phys. Rev. A 93, 053624 (2016)

[2] A. Golubeva, A. Sotnikov, A. Cichy, J. Kuneš, W. Hofstetter, Phys. Rev. B 95, 125108 (2017)

Chair: MK

Upcoming seminars can be found at MTPR

Sincerely yours, *Michał Banaszak Maciej Krawczyk Adam Miranowicz*

Informację wprowadził/a: **Marek Nowak**

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