Detection of quantum signals free of classical noise via quantum correlation

Extracting valuable signals is essential for both classical and quantum technologies. Traditional noise filtering techniques depend on distinct patterns of signal and noise in frequency or time domains, which constrains their applicability, especially in quantum sensing. Here, we introduce a signal-nature-based (not signal-pattern-based) approach that singles out a quantum signal from its classical noise background by employing the intrinsic quantum nature of the system. We design an innovative protocol to extract the Quantum Correlation signal and use it to single out the signal of a remote nuclear spin from its overwhelming classical noise backgrounds, which is impossible to be accomplished by conventional filter methods. Our research highlights the quantum/classical nature as a novel degree of freedom in quantum sensing. The broader implementation of this quantum nature-based methodology paves the way for new avenues in quantum research.