Gozzelino Michele, Micalizio Salvatore, Levi Filippo, Godone Aldo, Calosso Claudio Eligio
IEEE Trans Ultrason Ferroelectr Freq Control. 2018 Jul;65(7):1294-1301. doi: 10.1109/TUFFC.2018.2828987.
We describe a method to stabilize the amplitude of the interrogating microwave field in compact atomic clocks working in a Ramsey approach. In this technique, we take advantage of the pulsed regime to use the atoms themselves as microwave amplitude discriminators. Specifically, in addition to the dependence on the microwave detuning, the atomic signal after the Ramsey interrogation acquires a dependence on the microwave pulse area (amplitude times duration) that can be exploited to implement an active stabilization of the microwave field amplitude, in a similar way in which the Ramsey clock signal is used to lock the local oscillator frequency to the atomic reference. The stabilization allows us to reduce the microwave field-amplitude fluctuations, which in turn impact the clock frequency through cavity pulling. The proposed technique has shown to be effective to improve our clock frequency stability on medium and long term. We demonstrate the method for a vapor-cell clock working with a hot sample of atoms, but it can be extended to cold-atom compact clocks.
我们描述了一种在采用拉姆齐方法工作的紧凑型原子钟中稳定询问微波场振幅的方法。在这项技术中，我们利用脉冲工作模式，将原子本身用作微波振幅鉴别器。具体而言，除了对微波失谐的依赖外，拉姆齐询问后的原子信号还获得了对微波脉冲面积（振幅乘以持续时间）的依赖，这可用于实现微波场振幅的主动稳定，类似于利用拉姆齐时钟信号将本地振荡器频率锁定到原子参考频率的方式。这种稳定化使我们能够减少微波场振幅波动，而微波场振幅波动又会通过腔牵引影响时钟频率。所提出的技术已证明在中长期内有效提高我们的时钟频率稳定性。我们展示了该方法在使用热原子样本的汽泡室时钟中的应用，但它也可扩展到冷原子紧凑型时钟。
