Xie Tianyu, Zhao Zhiyuan, Kong Xi, Ma Wenchao, Wang Mengqi, Ye Xiangyu, Yu Pei, Yang Zhiping, Xu Shaoyi, Wang Pengfei, Wang Ya, Shi Fazhan, Du Jiangfeng
Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China.
CAS Key Laboratory of Microscale Magnetic Resonance and Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China.
Sci Adv. 2021 Aug 6;7(32). doi: 10.1126/sciadv.abg9204. Print 2021 Aug.
The use of entangled sensors improves the precision limit from the standard quantum limit (SQL) to the Heisenberg limit. Most previous experiments beating the SQL are performed on the sensors that are well isolated under extreme conditions. Here, we demonstrate a sub-SQL interferometer at ambient conditions by using a multispin system, namely, the nitrogen-vacancy (NV) defect in diamond. We achieve two-spin interference with a phase sensitivity of 1.79 ± 0.06 dB beyond the SQL and three-spin interference with a phase sensitivity of 2.77 ± 0.10 dB. Besides, a magnetic sensitivity of 0.87 ± 0.09 dB beyond the SQL is achieved by two-spin interference for detecting a real magnetic field. Particularly, the deterministic and joint initialization of NV negative state, NV electron spin, and two nuclear spins is realized at room temperature. The techniques used here are of fundamental importance for quantum sensing and computing, and naturally applicable to other solid-state spin systems.
纠缠传感器的使用将精度极限从标准量子极限（SQL）提升至海森堡极限。此前大多数突破SQL的实验都是在极端条件下对隔离良好的传感器进行的。在此，我们通过使用多自旋系统，即金刚石中的氮空位（NV）缺陷，在环境条件下展示了一种亚SQL干涉仪。我们实现了相位灵敏度为1.79±0.06 dB（超越SQL）的双自旋干涉以及相位灵敏度为2.77±0.10 dB的三自旋干涉。此外，通过双自旋干涉检测真实磁场时，实现了0.87±0.09 dB（超越SQL）的磁灵敏度。特别地，在室温下实现了NV负态、NV电子自旋和两个核自旋的确定性联合初始化。这里所采用的技术对于量子传感和计算至关重要，并且自然适用于其他固态自旋系统。
