Certifying entanglement of spins on surfaces using ESR-STM

TL;DR

This paper introduces a protocol using ESR-STM to detect entanglement in surface spin arrays, extending the theoretical framework to anisotropic interactions and demonstrating practical measurement methods.

Contribution

It generalizes the entanglement witness theorem to anisotropic Zeeman interactions and proposes a feasible ESR-STM based measurement technique for surface spins.

Findings

Entanglement can be certified in antiferromagnetic spin dimers and trimers.

The method is compatible with current ESR-STM technology.

Theoretical extension to anisotropic Zeeman interactions.

Abstract

We propose a protocol to certify the presence of entanglement in artificial on-surface atomic and molecular spin arrays using electron spin resonance carried by scanning tunnel microscopes (ESR-STM). We first generalize the theorem that relates global spin susceptibility as an entanglement witness to the case of anisotropic Zeeman interactions, relevant for surfaces. We then propose a method to measure the spin susceptibilities of surface-spin arrays combining ESR-STM with atomic manipulation. Our calculations show that entanglement can be certified in antiferromagnetically coupled spin dimers and trimers with state of the art ESR-STM magnetometry.