Many Facets of Laser-Atom and Dipole-Dipole Interactions

最近在量子计算机和量子模拟器中使用原子和离子作为工作元素取得了实质性进展。此外，也有一些建议，以控制原子或离子的复杂排列来操纵激光的性质。欧洲和亚洲正在积极开展这类研究，美国在这一领域的竞争能力可能对几种技术至关重要。该项目将尝试更好地模拟量子计算机和/或模拟器中的几个常见过程，这些过程通常以近似的方式处理；目标是预测哪些特性对于成功的量子计算机是重要的。此外，该小组将探索原子之间的合作影响在这些系统中所起的作用，以及许多相互作用是否会导致质量不同的结果。对这些系统的基本理解是困难的；并且需要开发可以广泛使用的新工具。由于量子计算机或模拟器的操作依赖于脆弱的量子过程，因此了解原子或离子与激光如何在精细的细节水平上相互作用是很重要的。即使很小的影响也会累积在许多原子或离子上，导致失败。因此，这个项目的一个主要驱动力是减少近似，以便可靠地预测这些机器将如何运行。本提案中项目的目标是了解如何微小但可能重要的影响将限制量子计算机的有效性，将控制如何通过与原子图案阵列的相互作用来操纵光，或者由于原子之间的远距离偶极子-偶极子相互作用而显示有趣的集体现象。一组项目解决了量子计算机中光与原子的相互作用如何导致原子的质量中心运动与其内部状态的纠缠，这可能是退相干的来源；这种纠缠由光子吸收和/或发射的动量踢引起。第二组项目在比迄今为止更详细的层面上模拟了原子的图案阵列如何操纵，例如，光束的方向；例如，从阵列反射的每个光子必须有一个动量踢，但是这个动量踢是相干的还是非相干的分布在几个原子上，还没有被研究过。最后一组项目被提出来理解当许多原子与光相互作用时产生的基本物理过程；例如，当角动量大于零时，许多原子相干可以在基态内发展。所有项目的首要目标是研究涉及许多粒子的复杂量子现象，其中它们之间的相互作用是通过延迟和量子化电磁场进行的。另一个兴趣是理解复杂的行为是如何从简单的相互作用中产生的，因此，这可能会引起广泛的兴趣。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。

There has been substantial recent progress using atoms and ions as the working elements in quantum computers and quantum simulators. In addition, there are several proposals to use controlled atoms or ions in complex arrangements to manipulate properties of laser light. Studies of this type are being aggressively pursued in Europe and Asia, and the ability of the US to compete in this arena could be crucial for several technologies. This project will attempt to better simulate several common processes in quantum computers and/or simulators that are often treated in an approximate manner; the goal is to predict which properties are important for a successful quantum computer. In addition, the group will explore the role that cooperative affects among atoms play in these systems and whether the many interactions lead to qualitatively different outcomes. The basic understanding of these systems is difficult; and will require the development of new tools that could be of widespread utility. Because the operation of quantum computers or simulators depends on fragile quantum processes, it is important to understand how the atoms or ions and the lasers interact at a fine level of detail. Even small effects can accumulate over the many atoms or ions and lead to failure. Thus, a major drive of this project is to reduce the approximations in order to reliably predict how these machines will operate.The goal of the projects in this proposal is to understand how small, but possibly important, effects will limit the effectiveness of quantum computers, will control how light is manipulated through the interaction with patterned arrays of atoms, or will display interesting collective phenomena due to the long range dipole-dipole interaction between atoms. One set of projects addresses how the interaction of light with atoms in quantum computers can lead to entanglement of the center of mass motion of the atom with its internal states, which can be a source of decoherence; this entanglement is caused by the momentum kick of photon absorption and/or emission. A second set of projects simulates, at a more detailed level than performed to date, how a patterned array of atoms can manipulate, for example, the direction of a light beam; for example, each photon reflecting from the array must give a momentum kick but whether the kick is coherently or is incoherently spread over several atoms has not been investigated. A last group of projects is proposed to understand basic physics processes that arise when many atoms interact with light; as an example, many atom coherences can develop within the ground state when it has angular momentum greater than zero. The overarching goal for all projects is to investigate complex quantum phenomena involving many particles where the interaction between them is through the retarded and quantized electromagnetic field. Another interest is in understanding how complex behavior can emerge from simple interactions and, thus, could be of wide interest.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.