Ultracold atoms in Lieb lattices

Cui Hai

A scheme is proposed for detection of the topology in the one-dimensional Afeck-Kennedy-Lieb-Tasaki model, based on ultracold spinor atomic gas in an optical lattice. For this purpose, a global operation O(θ) is introduced with respect to the breaking of spinrotational symmetry. Consequently, the topology can be manifested unambiguously by identifying the special values of θ where the expectation value of the global operator with degenerate ground states is vanishing. Furthermore, experimentally θ can be detected readily by the interference of ultracold atomic gases. This scheme can be implemented readily in experiment since it does not need the addressing of individual atoms or the probing of a boundary.

Gaia Donati

Immanuel Bloch

Jacopo Settino, Nicola Lo Gullo, Francesco Plastina +1 more

The single-particle spectral function of a strongly correlated system is an essential ingredient to describe its dynamics and transport properties. We develop a method to evaluate exactly the spectral function for a gas of one-dimensional bosons with infinitely strong repulsions valid for any type of external confinement. Focusing on the case of a lattice confinement, we find that the spectral function displays three main singularity lines. One of them is due uniquely to lattice effects, while the two others correspond to the Lieb-I and Lieb-II modes occurring in a uniform fluid. Differently from the dynamical structure factor, in the spectral function the Lieb-II mode shows a divergence, thus providing a route to probe such mode in experiments with ultracold atoms.

Nathan E. Lundblad

H. T. Cui, Gui Yang, Junlong Tian