Wannier-Stark ladders and Stark shifts of excitons in Mott insulators

TL;DR

This paper studies how a dc electric field causes energy levels in one-dimensional Mott insulators to discretize into Wannier-Stark ladders and induces Stark shifts in exciton levels, revealing new optical spectral features.

Contribution

It demonstrates the emergence of Wannier-Stark ladders and Stark shifts in Mott insulators under electric fields, supported by an effective model in the strong-coupling regime.

Findings

Discretized peaks appear in optical conductivity spectra under electric field.

Peak positions match energy levels from an effective model.

Mott insulators can be used to explore Stark discretization phenomena.

Abstract

External-field driven energy-level discretization, such as Landau quantization or Stark localization, is one of the most intriguing phenomena in quantum systems. We investigate the emergence of the Wannier-Stark ladder coming from the particle-hole continuum and the Stark shifts of the exciton levels in one-dimensional Mott insulators under the dc electric field. The discretized peak structure in the optical-conductivity spectra newly appears by applying the dc electric field, and the positions of these peaks can be reproduced from the energy levels of a simple effective model in the strong-coupling regime. Our results not only suggest that Mott insulators can serve as a viable platform for Stark discretization, but also pave the way for investigations of dynamical properties in correlated many-body systems under a dc electric field.