Baumgart I, Cai J-M, Retzker A, Plenio M B, Wunderlich Ch
Department Physik, Naturwissenschaftlich-Technische Fakultät, Universität Siegen, 57068 Siegen, Germany.
School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China.
Phys Rev Lett. 2016 Jun 17;116(24):240801. doi: 10.1103/PhysRevLett.116.240801.
Precision sensing, and in particular high precision magnetometry, is a central goal of research into quantum technologies. For magnetometers, often trade-offs exist between sensitivity, spatial resolution, and frequency range. The precision, and thus the sensitivity of magnetometry, scales as 1/sqrt[T_{2}] with the phase coherence time T_{2} of the sensing system playing the role of a key determinant. Adapting a dynamical decoupling scheme that allows for extending T_{2} by orders of magnitude and merging it with a magnetic sensing protocol, we achieve a measurement sensitivity even for high frequency fields close to the standard quantum limit. Using a single atomic ion as a sensor, we experimentally attain a sensitivity of 4.6 pT/sqrt[Hz] for an alternating-current magnetic field near 14 MHz. Based on the principle demonstrated here, this unprecedented sensitivity combined with spatial resolution in the nanometer range and tunability from direct current to the gigahertz range could be used for magnetic imaging in as of yet inaccessible parameter regimes.
精确传感，尤其是高精度磁力测量，是量子技术研究的核心目标。对于磁力计而言，灵敏度、空间分辨率和频率范围之间往往存在权衡。磁力测量的精度，进而灵敏度，与传感系统的相位相干时间(T_2)成(1/\sqrt{T_2})比例关系，(T_2)起着关键决定因素的作用。采用一种动态解耦方案，该方案可将(T_2)延长几个数量级，并将其与磁传感协议相结合，我们甚至对接近标准量子极限的高频场也实现了测量灵敏度。使用单个原子离子作为传感器，我们通过实验在14兆赫兹附近的交变磁场中获得了4.6皮特斯拉/根号赫兹的灵敏度。基于此处展示的原理，这种前所未有的灵敏度与纳米级空间分辨率以及从直流到吉赫兹范围的可调性相结合，可用于目前尚未涉足的参数区域的磁成像。
