AC sensing wtih Spin Locked 13C Nuclear Spins

Quantum sensors are one of the most prominent candidates to achieve submicronscale NMR spectroscopy. However, such sensors predominantly operate in low-field regime, which exhibits low chemical resolution. Here, we demonstrate an AC sensing scheme in high field using hyperpolarized 13C nuclear spins in diamonds that can be exploited to achieve submicronscale NMR microscopy. The 13C nuclear spins are first hyperpolarized and initialized by transferring polarization from a central NV center. After placing the 13C nuclear spins in an initial transverse state, we spin lock them to extend their lifetimes (in order of minutes). As a proof of concept, we apply and measure an AC field with varying amplitude and frequency with high resolution, using the phases of the 13C nuclear spins in the rotating frame.