Dynamical Laser Cooling of Ultranarrow Linewidth Atoms and Molecules

这个理论研究项目探索了一个令人兴奋的新想法，用激光将原子和分子冷却到比外太空冷100万倍以上的温度。这种被称为SWAP冷却的创新技术，采用了高度相干的激光器，其纯色是周期性调制的。这项新技术最初是在实验室中偶然发现的，它有望推动在操纵和控制量子气体方面所能取得的进展，从而在科学和技术方面具有广泛的潜在应用。这并不是第一个激光冷却的建议；事实上，在过去的二三十年里，利用激光控制和冷却原子气体的想法已经得到了广泛的探索，并导致了许多方法的发展，这些方法每天都在原子物理实验室中使用。然而，这种新方法有可能大规模扩展原子和分子的范围，可以考虑用于量子科学和量子计算应用，并提供改进最先进的原子钟（用于GPS卫星导航等系统）。这个新颖的想法是基于这样一个前提，即具有两个价电子的系统（ii族元素和其他类似的原子和分子系统）所提供的极端相干性为激光科学提供了一个新的和令人兴奋的前沿。在这些系统中，极弱的偶极子跃迁的存在导致传统的激光冷却方法难以实现，部分原因是激光频率的稳定性要求很高。本文提出的新思路是利用近共振激光场，其强度或频率可以及时调制。这可能会放大强相干力的作用，同时降低光子的耗散和自发散射的作用，否则会增加可实现的温度。其目标是实现频率标准的十倍改进，从而直接转化为当前技术的潜在重大改进，从改进的计量，到先进的通信，到下一代导航和定位系统的精密设备。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This theoretical research project explores a new and exciting idea where lasers are used to cool atoms and molecules to temperatures more than a million times colder than deep space. This innovative technique, dubbed SWAP cooling, employs extremely coherent lasers whose pure color is periodically modulated. Starting first as an accidental experimental discovery in the laboratory, this new technique promises to push back the frontier of what can be achieved in manipulating and controlling quantum gases, and to thereby have a broad range of potential applications in science and technology. This is not the first laser-cooling proposal; indeed the idea for using lasers to control and cool atomic gases has been explored extensively over the past two or three decades, and has led to the development of many methods that are used every day in atomic physics laboratories. However, this new approach has the potential to massively expand the range of atoms and molecules that can be considered for quantum science and quantum computation applications, and offers to improve state-of-the-art atomic clocks (used in such systems as GPS satellites for navigation). The novel idea is based on the premise that the extreme coherence offered by systems that have two valence electrons (group-II elements and other similar atomic and molecular systems) offers a new and exciting frontier for laser sciences. In these systems, the presence of extremely weak dipole transitions causes the implementation of traditional laser-cooling approaches to be difficult due in part to the demanding stability requirements for the laser frequencies. The new idea here is that near-resonant laser fields can be used whose intensity or frequency may be modulated in time. This may amplify the effects of strong coherent forces while simultaneously reducing the role of dissipative and spontaneous scattering of photons that would otherwise increase the realizable temperatures. The aim is to achieve, say, a ten-fold improvement in frequency standards that translates directly into potential major improvements in current technologies, ranging from improved metrology, to advanced communication, to the next generation of precision devices for navigation and positioning systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.