## Quantum Simulations with Ultracold Atoms and Ions: Beyond Standard Optical Lattices

**Note:**Note special day, time: Friday at 10 AM

**Speaker:**Prof. Walter Hofstetter, Goethe University, Frankfurt

**When:**November 21, 2014 (Fri), 10:00AM to 11:00AM (add to my calendar)

**Location:**SCI 328

**Hosted by:**Anatoli Polkovnikov

*This event is part of the Condensed Matter Theory Seminar Series. *

Abstract:
Recent years have witnessed dramatic progress in experimental control and refinement of quantum simulations

based on ultracold atoms. Particularly rich many-body physics arises in the presence of multiple atomic or ionic species,
artificial gauge fields and strong interactions, which I will highlight for the following examples:

1) We propose and theoretically investigate a hybrid system composed of a crystal of trapped ions coupled to
ultracold fermions. This system combines the advantages of scalability and tunability of ultracold atoms with
the high fidelity operations and detection offered by trapped ions. It also features close analogies to natural solid-state systems,
as the atomic degrees of freedom couple to phonons of the ion lattice.
We derive the effective low energy Hamiltonian and discuss possible experimental scenarios

such as a Peierls-like transition into a dimerized state.

2) Recent experiments in ultracold atoms and photonic analogs have reported the implementation of artificial gauge fields in lattice systems, facilitating the realization of topological phases. We investigate the Haldane honeycomb lattice tight-binding model, for bosons with local interactions at filling one. We analyze the ground state phase diagram and uncover three distinct phases: a uniform superfluid (SF), a chiral superfluid (CSF) and a plaquette Mott insulator with local current loops (PMI).

3) We study finite-temperature magnetic phases of three-component mixtures of ultracold fermions with repulsive interactions in optical lattices with simple cubic or square geometry by means of dynamical mean-field theory (DMFT). We focus on the case of one particle per site at moderate interaction strength, where we observe a sequence of thermal phase transitions into two- and three-sublattice ordered states. We find that long-range ordering in three-component mixtures should be observable at comparable temperatures as in two-component mixtures.