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Figure 1 | EPJ Quantum Technology

Figure 1

From: Dynamical nuclear polarization using multi-colour control of color centers in diamond

Figure 1

Protocol of DNP using multi-color control of NV centers in diamond. (a) Standard dynamical polarization transfer based on Hartmann-Hann resonance. A nitrogen-vacancy center spin in diamond is coupled with nuclei via magnetic dipole-dipole interaction. A microwave driving field satisfying the Hartmann-Hahn condition \(\Omega=\omega_{L}\) induces a resonant exchange interaction between NV center spin and nuclei, which facilitates polarization transfer from NV center spin to nuclei. (b) The repetitive dynamical nuclear polarization cycle: (1) the NV centers are initialized by a green laser pulse; (2) a \((\frac{\pi}{2})_{y}\) pulse with the frequency \(\omega(t)\) prepares the NV centers into the dressed spin down state; (3) the frequency-modulated microwave fields are applied to facilitate the polarization transfer from the NV center to the nuclei. (c) The frequency sweep strategy for dynamical nuclear polarization using an ensemble of NV centers. The frequency of the microwave driving field sweeps linearly in time, namely \(\omega(t)=\omega(0)+\nu t\). The NV centers with different transition frequencies are resonantly driven sequentially when the microwave frequency \(\omega(t)\) comes close to its individual transition frequency.

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