Orbital-driven melting of a bosonic Mott insulator in a shaken optical lattice

Understand

In order to study the interplay between localized and dispersive orbital states in a system of ultracold atoms in an optical lattice, we investigate the possibility to coherently couple the lowest two Bloch bands by means of resonant periodic forcing.

• Considering bosons in one dimension, it is shown that a strongly interacting Floquet system can be realized, where at every lattice site two (and only two) near-degenerate orbital states are relevant.
• By smoothly tuning both states into resonance we find that the system can undergo an orbital-driven Mott-insulator-to-superfluid transition.
• As an intriguing consequence of the kinetic frustration in the system, this transition can be either continuous or first-order, depending on parameters such as lattice depth and filling.