Qu Weizhi, Jin Shenchao, Sun Jian, Jiang Liang, Wen Jianming, Xiao Yanhong
Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Fudan University, 200433, Shanghai, China.
Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL, 60637, USA.
Nat Commun. 2020 Apr 9;11(1):1752. doi: 10.1038/s41467-020-15557-6.
Weak measurement (WM) with state pre- and post-selection can amplify otherwise undetectable small signals and thus has potential in precision measurement applications. Although frequency measurements offer the hitherto highest precision due to the stable narrow atomic transitions, it remains a long-standing interest to develop new schemes to further escalate their performance. Here, we demonstrate a WM-enhanced correlation spectroscopy technique capable of narrowing the resonance linewidth down to 0.1 Hz in a room-temperature atomic vapour cell. The potential of this technique for precision measurement is demonstrated through weak magnetic-field sensing. By judiciously pre- and post-selecting frequency-modulated input and output optical states in a nearly orthogonal manner, a sensitivity of 7 fT Hz at a low frequency near DC is achieved using only one laser beam with 15 µW of power. Additionally, our results extend the WM framework to a non-Hermitian Hamiltonian and shed new light on metrology and bio-magnetic field sensing.
具有态预选和后选的弱测量（WM）可以放大原本无法检测到的小信号，因此在精密测量应用中具有潜力。尽管由于稳定的窄原子跃迁，频率测量提供了迄今为止最高的精度，但开发新的方案以进一步提升其性能仍然是一个长期的研究热点。在此，我们展示了一种WM增强的相关光谱技术，该技术能够将室温原子蒸汽室中的共振线宽缩小至0.1 Hz。通过弱磁场传感证明了该技术在精密测量方面的潜力。通过以近乎正交的方式明智地预选和后选调频输入和输出光学态，仅使用一束功率为15 μW的激光束，在接近直流的低频处实现了7 fT/Hz的灵敏度。此外，我们的结果将WM框架扩展到了非厄米哈密顿量，并为计量学和生物磁场传感提供了新的思路。
