Interferometric Quantum Scattering in a Juggling Atomic Clock

这个实验研究计划将精确地研究超冷铯原子在原子钟中的量子散射，原子钟可以改变原子云。该小组最近展示了一种全新的散射实验，在这种实验中，一个铯原子在两种叠加状态下制备，在原子钟中发射的另一个云中的原子中散射出去。叠加态的每个状态都会经历散射相移，这是对原子之间相互作用强度的一种测量。通过仅检测每个原子波函数的散射部分，可以直接观察到散射相移的差异作为时钟的频移。这种技术的一个独特之处在于，频移与原子密度无关。这项技术使得散射测量具有原子钟般的精度。期望以前所未有的精度测量原子散射长度。他们将精确地研究铯原子不同基态的散射作为碰撞能量和磁场的函数，以明确地约束超冷铯-铯相互作用。他们将测量阈值效应，并尝试识别费什巴赫和形状共振。他们还可以探测由于杂耍碰撞引起的频率变化，这对提高未来时钟的稳定性很重要。在狭窄的费什巴赫共振附近对散射相移进行高精度测量，可能会严格限制基本常数的时间变化，例如电子-质子质量比。该计划的广泛影响包括在激光，电光，射频和微波技术，超高真空，原子钟和频率控制等许多现代技术领域培养研究生和博士后研究人员。这个小组对原子钟的发展做出了重大贡献，包括激光冷却铷原子钟、空间时钟设计、杂耍原子喷泉、用于光学频率时钟的超稳定激光器，以及微波腔和冷碰撞的研究。本研究将提高铯原子钟的精度和稳定性，实现SI秒的定义。这项工作将影响对超冷原子-原子相互作用的理解，在清晰度和精度上取得突破。

This experimental research program will precisely study quantum scattering of ultracold cesium atoms in an atomic clock that juggles clouds of atoms. The group has recently demonstrated a fundamentally new type of scattering experiment in which a cesium atom, prepared in a superposition two states, scatters off of atoms in another cloud launched in the atomic clock. Each state of the superposition experiences a scattering phase shift, a measure of the strength of the interaction between the atoms. By detecting only the scattered part of each atom's wave function, the difference of the scattering phase shifts is directly observed as a frequency shift of the clock. A unique feature of this technique is that the frequency shift is independent of the atomic density. The technique allows scattering measurements with atomic-clock-like accuracy. Measurements of atomic scattering lengths with unprecedented accuracy are expected. They will precisely study the scattering of the different ground-substates of cesium atoms as a function of collision energy and magnetic field to unambiguously constrain ultracold cesium-cesium interactions. They will measure threshold effects and try to identify Feshbach and shape resonances. They can also probe the frequency shifts due to juggling collisions, important for improving the stability of future clocks. Highly precise measurements of scattering phase shifts near a narrow Feshbach resonance may stringently constrain the time variation of fundamental constants, such as the electron-proton mass ratio.Broader impacts of this program include the training of graduate students and postdoctoral researchers in many areas of modern technology from lasers, electro-optics, radio-frequency and microwave techniques, ultra-high vacuum, and atomic clocks and frequency control. This group has significantly contributed to the development of atomic clocks, including laser-cooled rubidium clocks, space clock design, juggling atomic fountains, ultra-stable lasers for optical frequency clocks, and studies of microwave cavities and cold collisions. The proposed research will lead to higher accuracy and stability of the cesium clocks that realize the definition of the SI second. The work will impact the understanding of ultracold atom-atom interactions with a breakthrough in clarity and precision.