Manipulating light-matter interactions in bulk anisotropic metamaterials

非技术描述：光与物质以许多不同的方式相互作用，这些方式在我们的日常生活中可以观察到。这包括例如人眼的视网膜杆和视锥中的化学过程的散射、反射、折射、吸收或激发。特定的光-物质相互作用的可能性和强度由所谓的选择规则决定。许多光-物质相互作用过程是被禁止的，或者更准确地说，是极不可能的，因此限制了光学材料和过程的基础研究和应用。操纵这些不可能的相互作用的能力可能会增强许多领域的基础知识，包括原子，分子和光学物理，光子学，化学和纳米技术。这项研究的重点是开发新的纳米结构光学材料和结构，称为超材料，有助于创造特殊形状的光束。这些定制的光束能够访问那些以前禁止的光-物质相互作用。除了其基础科学意义之外，这项研究还可以在光谱学和传感设备，光伏系统和量子计算设备中应用。这种实践经验，沿着接触最先进的科学问题及其调查，有助于为参与学生未来的科学和工程职业做好充分准备。技术说明：在电偶极近似中不允许的原子和分子的光谱跃迁，但由于物质和辐射之间的相互作用中的高阶项而发生，称为偶极禁戒。原子中的偶极禁戒光跃迁构成了下一代原子钟的基础，也是量子信息处理器和量子模拟器中使用的高保真量子比特的基础。然而，偶极禁戒跃迁非常弱，因此表现出窄的自然线宽。 最近，人们认识到，轨道角动量，或涡旋光束可以使原子，分子和人造原子或纳米晶体中的量子禁戒跃迁成为可能。然而，过渡率取决于光束的大小，并增加时，涡旋光束的尺寸减小。拟议的研究的目标是调查和证明探测禁止使用轨道角动量携带光束，已被缩小到亚波长尺度，使用强各向异性超材料结构的人造原子跃迁的可能性。轨道角动量光束与原子的相互作用使空心光束陷阱成为可能，提高了受激发射耗尽显微镜的空间分辨率，促进了量子信息处理。参与该项目的研究生和本科生获得光谱学、纳米纤维和新型纳米结构材料光学表征方面的实践经验。该奖项反映了NSF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。

Nontechnical description: Light interacts with matter in many different ways that can be observed in our everyday life. This includes scattering, reflection, refraction, absorption or excitation of chemical processes in, for example, retinal rods and cones of the human eye. The likelihood and strength of a particular light-matter interaction is governed by so-called selection rules. Many light-matter interaction processes are forbidden, or more precisely, highly-improbable, therefore limiting fundamental studies and applications of optical materials and processes. The ability to manipulate these improbable interactions is likely to enhance fundamental knowledge in many fields, including atomic, molecular and optical physics, photonics, chemistry, and nanotechnology. This research focuses on developing new nanostructured optical materials and structures, termed metamaterials, that help create specially shaped light beams. These custom-made light beams enable accessing those previously forbidden light-matter interactions. Beyond its fundamental science significance, this research could enable applications in spectroscopy and sensing devices, photovoltaic systems and quantum computing devices. This hands-on experience, along with exposure to state-of-the-art scientific problems and their investigations, helps thoroughly prepare participating students for future science and engineering careers. Technical description: Spectroscopic transitions in atoms and molecules that are not allowed within the electric-dipole approximation, but occur due to higher-order terms in the interaction between matter and radiation, are called dipole-forbidden. Dipole-forbidden optical transitions in atoms form the basis of next-generation atomic clocks, and of high-fidelity qubits used in quantum information processors and quantum simulators. However, dipole-forbidden transitions are very weak and therefore exhibit narrow natural linewidths. Recently, it was realized that orbital angular momentum, or vortex beams can make symmetry-forbidden transitions possible in atoms, molecules, and artificial atoms or nanocrystals. However, the transition rate depends on the beam size and increases when the vortex beam size decreases. The goal of the proposed research is to investigate and demonstrate the possibility of probing forbidden transitions in artificial atoms using orbital angular momentum carrying beams that have been demagnified to subwavelength scales using strongly anisotropic metamaterial structures. Interactions of orbital angular momentum beams with atoms enable hollow-beam traps, improve the spatial resolution of stimulated emission depletion microscopy and facilitate quantum information processing. Graduate and undergraduate students involved in this project gain hands-on experience in spectroscopy, nanofabrication and optical characterization of novel nanostructured materials.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.