Coherence Control of Weak Localization in Cold Atoms

冷原子弱局域化的相干控制

• 批准号: 2011734
• 负责人: Charles Sukenik
• 金额: $ 29.94万
• 依托单位: Old Dominion University Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2011734&HistoricalAwards=false
• 关键词: Coherence; Control; Weak; Localization; Cold

In recent years, scientists have fine-tuned their ability to lower the temperature of some atoms and molecules to close to absolute zero on the Kelvin temperature scale. Atoms cooled down to this level, often referred to as “ultracold” atoms, behave differently than atoms at room temperature, especially when interacting with laser light. It is even possible to use laser light to hold atoms in place, countering the force of gravity. Such atoms are referred to as “trapped.” Trapped atoms can be studied as part of fundamental science investigations or used for real-world applications, like building very precise sensors or even deployed for a new class of computers known as “quantum computers.” Trapped atoms interacting with laser light can also be used to model other physical systems, for example, how electrons might travel in solids. This project explores how laser light, whose color is carefully controlled, scatters off of an ensemble of trapped, ultracold atoms. The experimental objectives of this project are twofold: 1) to study laser light scattering under conditions that have not been explored before to better understand the intricate details of the fundamental light scattering dynamics, and 2) to use additional lasers to actually control the light scattering process – not just to observe it. Accompanying these experiments in the laboratory will be an effort to refine the theoretical understanding of all of the observed physical phenomena so that the findings can be applied to other basic scientific and applied research problems. The project is directed towards investigation of unexplored areas of light scattering and transport in weakly disordered, ultracold atomic gases. In particular, coherent backscattering (CBS), an interference effect sometimes referred to as “weak-localization,” that results in enhanced scattering of light in the backwards direction, will be investigated in conjunction with electromagnetically-induced transparency-like conditions to explore potential control aspects to the light scattering process. Modification to the CBS effect will be measured, using light polarization, applied magnetic fields and atomic density as the principal “control knobs.” In a related project, the CBS effect will be investigated when the laser light is off-resonance from an atomic transition, and with variable polarization and applied magnetic fields. Here, an effect known as “anti-localization,” arising from hyperfine coherences that build up over time, is predicted – theoretically - to reduce the observed CBS signal. Beyond observation of this phenomena, of particular interest is measurement of the detuning dependence of the process to enable comparison to theoretical predictions and validate scattering models in this regime.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.

近年来，科学家们微调了他们在开尔文温度尺度上降低某些原子和分子温度接近绝对零的能力。原子冷却至该水平，通常称为“超低”原子，其行为与室温下的原子不同，尤其是在与激光相互作用时。甚至可以使用激光光将原子固定在适当的位置，以对抗重力。这种原子称为“被困”。可以将捕获的原子作为基本科学研究的一部分研究或用于现实世界应用的一部分，例如构建非常精确的传感器，甚至用于为新的计算机部署，称为“量子计算机”。与激光相互作用的被困原子也可以用于建模其他物理系统，例如电子如何以固体传播。该项目探索了仔细控制颜色的激光如何散布在被困的超低原子的合奏中。该项目的实验目标是双重的：1）在没有探索的条件下研究激光散射，然后才能更好地理解基本光散射动力学的复杂细节，以及2）使用其他激光器实际控制光散射过程 - 不仅要观察它。伴随实验室中的这些实验将是一种努力，以完善对所有观察到的物理现象的理论理解，以便可以将发现应用于其他基本的科学和应用研究问题。该项目针对弱无序的超低原子气体的光散射和运输的意外区域。特别是，连贯的反向散射（CBS），有时被称为“弱定位”的干扰效果，从而导致向后方向上的光的散射增强，并将与电磁诱发的透明透明条件一起研究，以探索光线散射过程的潜在控制方面。将使用光极化，施加的磁场和原子密度作为主“控制旋钮”来测量CBS效应的修饰。在一个相关的项目中，当激光光与原子过渡异议，具有变化的极化和施加的磁场时，将研究CBS效应。在这里，预测，一种被称为“抗本地化”的效果是由高精细的相干引起的，这些相干是随着时间的流逝而堆积的，可以预测 - 理论上 - 减少观察到的CBS信号。除了观察到这种现象外，特别感兴趣的是测量过程的依赖性，以便能够与理论预测进行比较，并在该制度中验证散射模型。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子和更广泛影响的审查标准来通过评估来通过评估来支持的。