Jiang Min, Huang Ying, Guo Chang, Su Haowen, Wang Yuanhong, Peng Xinhua, Budker Dmitry
Chinese Academy of Sciences Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China.
Chinese Academy of Sciences Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China.
Proc Natl Acad Sci U S A. 2024 Apr 23;121(17):e2315696121. doi: 10.1073/pnas.2315696121. Epub 2024 Apr 19.
Quantum amplification enables the enhancement of weak signals and is of great importance for precision measurements, such as biomedical science and tests of fundamental symmetries. Here, we observe a previously unexplored magnetic amplification using dark noble-gas nuclear spins in the absence of pump light. Such dark spins exhibit remarkable coherence lasting up to 6 min and the resilience against the perturbations caused by overlapping alkali-metal gas. We demonstrate that the observed phenomenon, referred to as "dark spin amplification," significantly magnifies magnetic field signals by at least three orders of magnitude. As an immediate application, we showcase an ultrasensitive magnetometer capable of measuring subfemtotesla fields in a single 500-s measurement. Our approach is generic and can be applied to a wide range of noble-gas isotopes, and we discuss promising optimizations that could further improve the current signal amplification up to [Formula: see text] with [Formula: see text]Ne, [Formula: see text] with [Formula: see text]Xe, and [Formula: see text] with [Formula: see text]He. This work unlocks opportunities in precision measurements, including searches for ultralight dark matter with sensitivity well beyond the supernova-observation constraints.
量子放大能够增强微弱信号，对于精密测量至关重要，例如生物医学科学和基本对称性测试。在此，我们在无泵浦光的情况下利用暗惰性气体核自旋观察到一种此前未被探索的磁放大现象。这种暗自旋展现出长达6分钟的显著相干性以及对由重叠碱金属气体引起的扰动的抗性。我们证明，所观察到的被称为“暗自旋放大”的现象能将磁场信号显著放大至少三个数量级。作为直接应用，我们展示了一种超灵敏磁力计，它能够在单次500秒测量中测量亚飞特斯拉场。我们的方法具有通用性，可应用于多种惰性气体同位素，并且我们讨论了有望进一步将当前信号放大提升至（对于²²Ne为[公式：见原文]，对于¹³²Xe为[公式：见原文]，对于³He为[公式：见原文]）的优化方案。这项工作为精密测量带来了机遇，包括以远超超新星观测限制的灵敏度搜寻超轻暗物质。
