# Revealing Hidden Antiferromagnetic Correlations in Doped Hubbard Chains via String Correlators

## TL;DR

This paper demonstrates the direct measurement of hidden antiferromagnetic correlations in doped Hubbard chains using quantum gas microscopy, revealing topological order through non-local string correlators and advancing understanding of spin-charge separation.

## Contribution

It introduces a novel experimental approach to observe hidden magnetic correlations in doped Hubbard chains via non-local string correlators.

## Key findings

- Detection of finite-range antiferromagnetic order in doped chains
- Observation of hidden magnetic correlations due to spin-charge separation
- Method extension potential to higher-dimensional systems

## Abstract

Topological phases, like the celebrated Haldane phase in spin-1 chains, defy characterization through local order parameters. Instead, non-local string order parameters can be employed to reveal their hidden order. Similar diluted magnetic correlations appear in doped one-dimensional lattice systems due to the phenomenon of spin-charge separation. Here we report on the direct observation of such hidden magnetic correlations via quantum gas microscopy of hole-doped ultracold Fermi-Hubbard chains. The measurement of non-local spin-density correlation functions reveals a hidden finite-range antiferromagnetic order, a direct consequence of spin-charge separation. Our technique demonstrates how topological order can directly be measured in experiments and it can be extended to higher dimensions to study the complex interplay between magnetic order and density fluctuations.