Energy Matching in NV Spin‐Phonon Interaction Enabling High‐Temperature Quantum Sensing via Lifetime Readout

ABSTRACT High‐temperature quantum sensing with NV centers has long been hindered by the spin contrast degradation from the thermally accelerated intersystem crossing (ISC) and the thermally induced fluorescence instability in the conventional intensity‐based readout. Here, we systematically investigate the NV spin‐phonon interaction in the ISC transition and the zero‐field splitting (ZFS) shift, which are two key aspects governing NV high‐temperature sensing performance. We report an energy matching between their characteristic phonon modes, which enables the ISC‐induced sensitivity degradation to be effectively compensated by the steepened slope of the ZFS shift, thereby preserving a high sensitivity even at high temperatures. This effect is particularly evident in the lifetime‐based optically detected magnetic resonance (ODMR) measurements, as the lifetime readout remains robust against thermally induced fluorescence instability at high temperatures. We reach a shot‐noise‐limited temperature sensitivity of 8.3 µK Hz −1/2 at 490 K in the lifetime‐based continuous‐wave ODMR scheme. Our work has opened up opportunities for highly sensitive NV quantum sensors under extreme conditions.