Quantum Physics2025-10-301 minarXiv:2510.26605expressDiamond spies peek at magnetic secrets under Earth's core pressureIn diamond, you can embed a “spy.” Simply replace a carbon atom with nitrogen: you get a defect that responds to magnetic fields and sends a light signal.Qingtao Hao·Ze-Xu He·Na Zuo·Yang Chen·Xiangzhuo Xing·Xiaoran Zhang·Xinyu Zhuang·Zhixiang Shi·Xin Chen·Jian-Gang Guo·Gang-Qin Liu·Xiaobing Liu·Yanming MaAlbert EinsteinAlexei KitaevAugustin-Louis Cauchysuperconductivitycarbon👍👎☆SimplePopularAdvanced