{"@context":"https://schema.org","@type":"ScholarlyArticle","headline":"Overcoming Frequency Resolution Limits Using a Solid-State Spin Quantum Sensor.","author":[{"@type":"Person","name":"Qingyun Cao"},{"@type":"Person","name":"Genko T Genov"},{"@type":"Person","name":"Yaoming Chu"},{"@type":"Person","name":"Jianming Cai"},{"@type":"Person","name":"Yu Liu"},{"@type":"Person","name":"Alex Retzker"},{"@type":"Person","name":"Fedor Jelezko"}],"datePublished":"2025","isPartOf":{"@type":"Periodical","name":"Physical review letters"},"identifier":"https://doi.org/10.1103/llfg-s4rr","description":"\n 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 , 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\n \n \n t\n \n −\n 2\n \n \n \n in comparison to the standard\n \n \n t\n \n −\n 1\n \n \n \n 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 \n \n \n μ\n s\n \n \n . Our results highlight the potential of quantum sensing to overcome conventional frequency resolution limitations, with broad implications for precision measurements.\n ","url":"https://innscience.ca/en/community/literature/doi_10_1103_llfg_s4rr"}