Measuring entanglement in condensed matter systems

TL;DR

This paper introduces a practical method to quantify entanglement in many-body systems like spin and cold atom setups using only standard experimental measurements, eliminating the need for full state characterization.

Contribution

The authors present a novel scheme to directly estimate a lower bound of entanglement from common experimental data without assumptions on the quantum state.

Findings

Entanglement can be bounded from neutron scattering cross sections.

Cold atom time-of-flight data can be used to estimate entanglement.

The method is versatile and applicable to various experimental setups.

Abstract

We show how entanglement may be quantified in spin and cold atom many-body systems using standard experimental techniques only. The scheme requires no assumptions on the state in the laboratory and a lower bound to the entanglement can be read off directly from the scattering cross section of Neutrons deflected from solid state samples or the time-of-flight distribution of cold atoms in optical lattices, respectively. This removes a major obstacle which so far has prevented the direct and quantitative experimental study of genuine quantum correlations in many-body systems: The need for a full characterization of the state to quantify the entanglement contained in it. Instead, the scheme presented here relies solely on global measurements that are routinely performed and is versatile enough to accommodate systems and measurements different from the ones we exemplify in this work.