Laser-Induced Commensurate-Incommensurate Transition of Charge Order in a Hubbard Superlattice

TL;DR

This study explores how laser pulses can induce a transition from commensurate to incommensurate charge order in a one-dimensional Hubbard superlattice, revealing a new method to control charge arrangements in quantum materials.

Contribution

It demonstrates a laser-induced commensurate-incommensurate transition driven by sublattice-selective doublon-holon dynamics in a Hubbard superlattice.

Findings

Laser excitation causes a shift in the charge structure factor peak.

The transition depends on laser frequency and intensity.

Charge order destabilization varies between sublattices.

Abstract

We investigate the nonequilibrium dynamics of charge density waves in a pumped one-dimensional Hubbard superlattice with staggered onsite Coulomb interactions at half-filling, using time-dependent exact diagonalization. In equilibrium, the system exhibits commensurate charge correlations consistent with the superlattice periodicity. Under laser excitation, the charge correlation function exhibits distinct behaviors across four representative frequencies, spanning both linear and nonlinear optical regimes. Notably, we observe a laser-induced commensurate-to-incommensurate transition in the charge order, manifested by a shift in the peak wavevector of the charge structure factor. This transition is driven by sublattice-selective doublon-holon dynamics, where the laser frequency and intensity determine whether excitations predominantly destabilize the charge order on the weakly or strongly interacting sublattice. Our analysis of the excitation spectrum and site-resolved correlation dynamics reveals the underlying mechanisms of this transition. These results suggest a promising optical strategy for controlling charge order in superlattice-based quantum materials.