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arXiv · 2506.20416

Overcoming frequency resolution limits using a solid-state spin quantum sensor

Qingyun Cao·Genko T. Genov·Yaoming Chu·Jianming Cai·Yu Liu·Alex Retzker·Fedor Jelezko
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Abstract

The ability to determine precisely the separation of two frequencies is fundamental to spectroscopy, yet the resolution limit poses a critical challenge: distinguishing two incoherent signals becomes impossible when their frequencies are sufficiently close. Here, we demonstrate a simple and powerful approach, dubbed {\it superresolution quantum sensing}, which experimentally resolves two nearly identical incoherent signals using a solid-state spin quantum sensor. By carefully choosing interrogation times that satisfy the superresolution condition, we eliminate quantum projection noise, overcoming the vanishing distinguishability of signals with near-identical frequencies. This leads to improved resolution, which scales as $t^{-2}$ in comparison to the standard $t^{-1}$ scaling. Together with a greatly reduced classical readout noise assisted by a nuclear spin, we are able to achieve sub-kHz resolution with a signal detection time of 80 microseconds. Our results highlight the potential of quantum sensing to overcome conventional frequency resolution limitations, with broad implications for precision measurements.

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Qingyun Cao, Genko T. Genov, Yaoming Chu, Jianming Cai, Yu Liu, Alex Retzker, Fedor Jelezko. 2025-12-25. Overcoming frequency resolution limits using a solid-state spin quantum sensor. https://doi.org/10.1103/llfg-s4rr

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