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arXiv · 2611.03343

Quartet state of the neutral nitrogen-vacancy center in diamond and optimized spin readout under near-infrared two-photon excitation

Nikoletta Jegenyes·Pál Maák·Vladimir Verkhovlyuk·László Himics·Tamás Váczi·Miklós Veres·Ádám Gali
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Abstract

Photoionization of the excited nitrogen-vacancy center (NV-) in diamond leaves the neutral defect in a metastable quartet state of unknown energy. Using two-photon optically detected magnetic resonance with a tunable femtosecond laser, we resolve its onset in the spin contrast at 1.23 +/- 0.02 eV and, with the ground-state threshold from the same setup, place the quartet 0.54 +/- 0.04 eV above the neutral ground state. The threshold sets the optimum excitation for spin readout at 1060-1075 nm, in the near-infrared tissue window, with 26-37% higher shot-noise-limited sensitivity than at 1030-1040 nm.

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Nikoletta Jegenyes, Pál Maák, Vladimir Verkhovlyuk, László Himics, Tamás Váczi, Miklós Veres, Ádám Gali. 2026-11-02. Quartet state of the neutral nitrogen-vacancy center in diamond and optimized spin readout under near-infrared two-photon excitation. https://arxiv.org/abs/2611.03343

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