Detection of Electron Paramagnetic Resonance of Two Electron Spins Using a Single NV Center in Diamond

TL;DR

This paper demonstrates a method to detect and characterize two electron spins interacting with a single NV center in diamond, advancing quantum sensing capabilities.

Contribution

The study introduces a technique for identifying and analyzing a coupled two-electron spin system using NV-detected EPR spectroscopy.

Findings

Successfully identified a single NV center coupled to two electron spins.

Determined the interaction strengths and number of surrounding spins.

Indicated the spins are likely surface spins on diamond.

Abstract

An interacting spin system is an excellent testbed for fundamental quantum physics and applications in quantum sensing and quantum simulation. For these investigations, detailed information of the interactions, e.g., the number of spins and their interaction strengths, is often required. In this study, we present the identification and characterization of a single nitrogen vacancy (NV) center coupled to two electron spins. In the experiment, we first identify a well-isolated single NV center and characterize its spin decoherence time. Then, we perform NV-detected electron paramagnetic resonance (EPR) spectroscopy to detect surrounding electron spins. From the analysis of the NV-EPR signal, we precisely determine the number of detected spins and their interaction strengths. Moreover, the spectral analysis indicates that the candidates of the detected spins are diamond surface spins. This study demonstrates a promising approach for the identification and characterization of an interacting spin system for realizing entangled sensing using electron spin as quantum reporters.