Quantum Sensing of Copper-Phthalocyanine Electron Spins via NV Relaxometry

Fuente: arXiv
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Main Authors: Li, Boning, Li, Xufan, Quan, Yifan, Harutyunyan, Avetik R, Cappellaro, Paola
Format: Preprint
Published: 2025
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author Li, Boning
Li, Xufan
Quan, Yifan
Harutyunyan, Avetik R
Cappellaro, Paola
author_facet Li, Boning
Li, Xufan
Quan, Yifan
Harutyunyan, Avetik R
Cappellaro, Paola
contents Molecular spin systems are promising candidates for quantum information processing and nanoscale sensing, yet their characterization at room temperature remains challenging due to fast spin decoherence. In this work, we use $T_1$ relaxometry of shallow nitrogen-vacancy (NV) centers in diamond to probe the electron spin ensemble of a polycrystalline copper phthalocyanine (CuPc) thin film. In addition to unequivocally identifying the NV-CuPc interaction thanks to its hyperfine spectrum, we further extract key parameters of the CuPc spin ensemble, including its correlation time and local lattice orientation, that cannot be measured in bulk electron resonance experiments. The analysis of our experimental results confirms that electron-electron interactions dominate the decoherence dynamics of CuPc at room temperature. Additionally, we demonstrate that the CuPc-enhanced NV relaxometry can serve as a robust method to estimate the NV depth with $\sim1$~nm precision. Our results establish NV centers as powerful probes for molecular spin systems, providing insights into molecular qubits, spin bath engineering, and hybrid quantum materials, and offering a potential pathway toward their applications such as molecular-scale quantum processors and spin-based quantum networks.
format Preprint
id arxiv_https___arxiv_org_abs_2511_03200
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Quantum Sensing of Copper-Phthalocyanine Electron Spins via NV Relaxometry
Li, Boning
Li, Xufan
Quan, Yifan
Harutyunyan, Avetik R
Cappellaro, Paola
Quantum Physics
Chemical Physics
Molecular spin systems are promising candidates for quantum information processing and nanoscale sensing, yet their characterization at room temperature remains challenging due to fast spin decoherence. In this work, we use $T_1$ relaxometry of shallow nitrogen-vacancy (NV) centers in diamond to probe the electron spin ensemble of a polycrystalline copper phthalocyanine (CuPc) thin film. In addition to unequivocally identifying the NV-CuPc interaction thanks to its hyperfine spectrum, we further extract key parameters of the CuPc spin ensemble, including its correlation time and local lattice orientation, that cannot be measured in bulk electron resonance experiments. The analysis of our experimental results confirms that electron-electron interactions dominate the decoherence dynamics of CuPc at room temperature. Additionally, we demonstrate that the CuPc-enhanced NV relaxometry can serve as a robust method to estimate the NV depth with $\sim1$~nm precision. Our results establish NV centers as powerful probes for molecular spin systems, providing insights into molecular qubits, spin bath engineering, and hybrid quantum materials, and offering a potential pathway toward their applications such as molecular-scale quantum processors and spin-based quantum networks.
title Quantum Sensing of Copper-Phthalocyanine Electron Spins via NV Relaxometry
topic Quantum Physics
Chemical Physics
url https://arxiv.org/abs/2511.03200