Interferometric Quantum Scattering in a Juggling Atomic Clock

这项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，原子钟可以操纵原子云。该小组最近展示了一种全新的散射实验，在这种实验中，一个铯原子以两个叠加态制备，在原子钟中发射的另一个云中的原子散射。叠加态的每一个状态都经历了散射相移，这是原子之间相互作用强度的一种度量。 通过只检测每个原子的波函数的散射部分，散射相移的差异被直接观察为时钟的频移。这种技术的一个独特之处是频率偏移与原子密度无关。该技术允许以原子钟般的精度进行散射测量。原子散射长度的测量具有前所未有的精度。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，以明确地限制超冷铯-铯相互作用。他们将测量阈值效应，并试图识别Feshbach和形状共振。它们还可以探测由于杂耍碰撞引起的频率偏移，这对提高未来时钟的稳定性很重要。 在窄Feshbach共振附近的散射相移的高精度测量可以严格地限制基本常数的时间变化，如电子-质子质量比。该计划的更广泛的影响包括在激光，电光，射频和微波技术，超高真空，原子钟和频率控制的许多现代技术领域的研究生和博士后研究人员的培训。该小组对原子钟的发展做出了重大贡献，包括激光冷却铷钟、空间钟设计、杂耍原子喷泉、用于光频钟的超稳定激光器以及微波腔和冷碰撞的研究。该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，并在清晰度和精确度方面取得突破。

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.