Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 7610001, Israel.
Nat Commun. 2017 Feb 10;8:14157. doi: 10.1038/ncomms14157.
Force sensors are at the heart of different technologies such as atomic force microscopy or inertial sensing. These sensors often rely on the measurement of the displacement amplitude of mechanical oscillators under applied force. The best sensitivity is typically achieved when the force is alternating at the mechanical resonance frequency of the oscillator, thus increasing its response by the mechanical quality factor. The measurement of low-frequency forces, that are below resonance, is a more difficult task as the resulting oscillation amplitudes are significantly lower. Here we use a single-trapped Sr ion as a force sensor. The ion is electrically driven at a frequency much lower than the trap resonance frequency. We measure small amplitude of motion by measuring the periodic Doppler shift of an atomic optical clock transition, enhanced using the quantum lock-in technique. We report frequency force detection sensitivity as low as 2.8 × 10 NHz.
力传感器是原子力显微镜或惯性传感等不同技术的核心。这些传感器通常依赖于测量施加力下机械振荡器的位移幅度。当力以振荡器的机械共振频率交替时，通常可以实现最佳灵敏度，从而通过机械品质因数增加其响应。测量低于共振的低频力是一项更具挑战性的任务，因为由此产生的振荡幅度要低得多。在这里，我们使用单个捕获的 Sr 离子作为力传感器。离子以远低于陷阱共振频率的频率进行电驱动。我们通过测量原子光学时钟跃迁的周期性多普勒频移来测量小幅度运动，利用量子锁定技术进行增强。我们报告的频率力检测灵敏度低至 2.8×10^-11NHz。
