Nonadiabatic Dynamics of Ultracold Fermions in Optical Superlattices

TL;DR

This paper investigates the real-time dynamics of ultracold fermions in optical superlattices using advanced numerical methods, revealing distinct behaviors in insulating states and effects of confinement.

Contribution

It applies adaptive time-dependent density matrix renormalization group to study nonadiabatic dynamics in a Hubbard model with superlattice potential, highlighting novel fermion pairing phenomena.

Findings

Mott insulator exhibits boson-like time evolution

Strong interactions induce fermion pairing and co-tunneling

Confining potential spatially localizes paired fermions

Abstract

We study the time-dependent dynamical properties of two-component ultracold fermions in a one-dimensional optical superlattice by applying the adaptive time-dependent density matrix renormalization group to a repulsive Hubbard model with an alternating superlattice potential. We clarify how the time evolution of local quantities occurs when the superlattice potential is suddenly changed to a normal one. For a Mott-type insulating state at quarter filling, the time evolution exhibits a profile similar to that expected for bosonic atoms, where correlation effects are less important. On the other hand, for a band-type insulating state at half filling, the strong repulsive interaction induces an unusual pairing of fermions, resulting in some striking properties in time evolution, such as a paired fermion co-tunneling process and the suppression of local spin moments. We further address the effect of a confining potential, which causes spatial confinement of the paired fermions.