Approaches to Measuring Entanglement in Chemical Magnetometers

TL;DR

This paper explores how quantum entanglement in chemical radical pair systems can be measured and utilized for magnetic field sensing, proposing methods for experimental estimation and analyzing error propagation.

Contribution

It introduces an entanglement witness and discusses observables for measuring entanglement in radical pair systems, linking entanglement lifetime to magnetometry.

Findings

Entanglement can be assessed using proposed observables.

Entanglement lifetime depends on magnetic field strength.

Measurement errors impact entanglement-based magnetometry.

Abstract

Chemical magnetometers are radical pair systems such as solutions of pyrene and N,N-dimethylaniline (Py-DMA) that show magnetic field effects in their spin dynamics and their fluorescence. We investigate the existence and decay of quantum entanglement in free geminate Py-DMA radical pairs and discuss how entanglement can be assessed in these systems. We provide an entanglement witness and propose possible observables for experimentally estimating entanglement in radical pair systems with isotropic hyperfine couplings. As an application, we analyze how the field dependence of the entanglement lifetime in Py-DMA could in principle be used for magnetometry and illustrate the propagation of measurement errors in this approach.