Bragg spectroscopy of trapped one dimensional strongly interacting bosons in optical lattices: Probing the cake-structure

TL;DR

This paper investigates how Bragg spectroscopy can reveal the shell structure of trapped one-dimensional strongly interacting bosons in optical lattices, highlighting the multi-branched excitation spectrum caused by inhomogeneity.

Contribution

It introduces a combined theoretical approach using Monte Carlo simulations, exact diagonalizations, and an effective fermionization model to analyze the excitation spectrum.

Findings

Multi-branched excitation spectrum due to inhomogeneity

Bragg spectroscopy can identify Mott insulator and superfluid shells

Inhomogeneity leads to distinct spectral features

Abstract

We study Bragg spectroscopy of strongly interacting one dimensional bosons loaded in an optical lattice plus an additional parabolic potential. We calculate the dynamic structure factor by using Monte Carlo simulations for the Bose-Hubbard Hamiltonian, exact diagonalizations and the results of a recently introduced effective fermionization (EF) model. We find that, due to the system's inhomogeneity, the excitation spectrum exhibits a multi-branched structure, whose origin is related to the presence of superfluid regions with different densities in the atomic distribution. We thus suggest that Bragg spectroscopy in the linear regime can be used as an experimental tool to unveil the shell structure of alternating Mott insulator and superfluid phases characteristic of trapped bosons.