Xu Minxiang, Jiang Min, Wang Yuanhong, Su Haowen, Huang Ying, Peng Xinhua
CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences, <a href="https://ror.org/04c4dkn09">University of Science and Technology of China</a>, Hefei 230026, China; Anhui Province Key Laboratory of Scientific Instrument Development and Application, <a href="https://ror.org/04c4dkn09">University of Science and Technology of China</a>, Hefei 230026, China; CAS Center for Excellence in Quantum Information and Quantum Physics, <a href="https://ror.org/04c4dkn09">University of Science and Technology of China</a>, Hefei 230026, China; and Hefei National Laboratory, <a href="https://ror.org/04c4dkn09">University of Science and Technology of China</a>, Hefei 230088, China.
Phys Rev Lett. 2024 Sep 27;133(13):133202. doi: 10.1103/PhysRevLett.133.133202.
Quantum sensing is crucial for precision measurements, yet quantum sensor sensitivity is often limited by the coherence time of the quantum system. Here, we demonstrate a method to enhance coherence time through cooperative spins. Using a tunable feedback circuit, we induce cooperation among noble-gas ^{129}Xe spins, resulting in an impressive 18-fold coherence enhancement. Moreover, we show that the cooperative ^{129}Xe spins can significantly amplify magnetic signals by at least 3 orders of magnitude. Magnetic field sensing assisted with such a cooperative spin amplifier realizes the sensitivity of 4 fT/Hz^{1/2} and surpasses the spin-projection noise of the embedded ^{87}Rb spin gas magnetometer. These results pave the way for a new class of "cooperative quantum sensors," and open up exciting prospects in fundamental physics.
量子传感对于精确测量至关重要，然而量子传感器的灵敏度常常受到量子系统相干时间的限制。在此，我们展示了一种通过协同自旋来延长相干时间的方法。利用一个可调谐反馈电路，我们诱导稀有气体(^{129}Xe)自旋之间产生协同作用，从而实现了令人瞩目的18倍相干增强。此外，我们还表明协同的(^{129}Xe)自旋能够将磁信号显著放大至少3个数量级。借助这种协同自旋放大器进行的磁场传感实现了(4 fT/Hz^{1/2})的灵敏度，并超越了嵌入式(^{87}Rb)自旋气体磁力计的自旋投影噪声。这些结果为一类新型的“协同量子传感器”铺平了道路，并在基础物理学领域开辟了令人兴奋的前景。
