CAREER: Dynamically Reconfigurable Cavity Quantum Electrodynamics with Solid-State Quantum Emitters

随着近几十年量子光子学的重大进步，利用光的量子本质进行更安全的通信、更快的计算和更强大的传感已迫在眉睫。一个主要的突出挑战在于设计光学量子系统和基于物质的量子系统之间的接口，以保持脆弱的量子态。这样的接口对于各种各样的任务是必要的，包括产生适合携带量子信息的光，存储和检索光子量子比特，以及调解光子之间的纠缠操作。要实现这些目标，通常需要增强光-原子相互作用的强度，而光-原子相互作用对于高效的量子设备来说自然太弱了。增强这种相互作用的一种常见方法是将原子耦合到光学谐振器或腔，通常是为单一应用而设计的精确制造的结构。这项研究旨在开发一种动态可重构的平台，通过在固态基质中使用高度相干的、低温冷却的稀土原子掺杂来将原子耦合到光学腔中，该固态基质可以在光谱和空间上进行定制，以形成腔镜和耦合的原子系综。这种灵活的平台可以用于各种重要的应用，例如高效和长寿命的光量子存储器，并可以集成到集成光学设备中。此外，还将开发一项新的本科生研究奖学金，面向对量子科学和工程感兴趣的学生，这些学生来自代表性较低的背景，重点是确保超越夏季研究经验的支持性指导。技术：拟议工作的目标是开发一种动态可重构的腔量子电动力学系统，该系统基于固态主机中高度相干、低温冷却的稀土原子掺杂的空间和光谱定制集合，该集合既形成了腔镜，又形成了耦合原子。低温下固体中的稀土原子表现出高度相干的类似原子的行为和能级结构，使它们适合于通过光谱烧孔来精确地定制其空间和光谱分布。交替光谱分布的一维阵列充当高反射光学反射镜。此外，多个亚稳态能级的存在使反射镜能够通过电磁感应透明在反射和透射态之间进行动态的、光学控制的切换。额外的光谱和空间调整可以实现更复杂的结构，包括可以相互耦合和与原子系综耦合的光学腔。这样，就形成了一个完全可重构的腔量子电动力学系统，不需要任何制作结构，具有动态可切换的腔镜的附加特征。这一方案将使基于稀土系综的光量子存储器存储光子量子比特的效率得到显著提高。稀土原子已经是最有前途的量子存储平台之一，将稀土系综耦合到光腔中，解决了在不牺牲存储效率的情况下制造具有长存储时间的紧凑型设备的突出挑战。以一种无需制造腔的可重新配置的方式实现这一点，使其成为一种灵活的平台，适用于各种有用的量子设备。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Harnessing the quantum nature of light for more secure communication, faster computation, and more powerful sensing is on the horizon today following significant advances in quantum photonics in recent decades. A major outstanding challenge lies in designing interfaces between optical and matter-based quantum systems that can preserve fragile quantum states. Such interfaces are necessary for a wide variety of tasks, including generating light suitable for carrying quantum information, storing and retrieving photonic qubits, and mediating entangling operations between photons. Achieving these goals generally requires enhancing the strength of the light-atom interaction, which is naturally too weak for efficient quantum devices. A common method to enhance this interaction is to couple the atoms to an optical resonator or cavity, typically a precisely fabricated structure designed for a single application. The research proposed here aims to develop a dynamically reconfigurable platform for coupling atoms to an optical cavity by using highly coherent, cryogenically-cooled rare-earth atom dopants in a solid-state host that can be spectrally and spatially tailored to form the cavity mirrors and the coupled atomic ensemble. This flexible platform can be used for a variety of important applications, such as efficient and long-lived quantum memory for light, and can be incorporated into integrated optical devices. In addition, a new undergraduate research fellowship that targets students interested in quantum science and engineering from underrepresented backgrounds will be developed, with a focus on ensuring supportive mentorship that extends beyond the summer research experiences.Technical: The objective of the proposed work is to develop a dynamically reconfigurable cavity quantum electrodynamics system based on a spatially and spectrally tailored ensemble of highly coherent, cryogenically-cooled, rare-earth atom dopants in a solid-state host, which forms both the cavity mirrors and the coupled atoms. Rare-earth atoms in solids at cryogenic temperatures exhibit highly coherent atom-like behavior and an energy level structure that makes them suited to precise tailoring of their spatial and spectral profile via spectral hole-burning. A one-dimensional array of alternating spectral profiles acts as a highly reflective optical mirror. Furthermore, the presence of multiple metastable energy levels enables dynamic, optically controlled switching of the mirror between reflective and transmissive states via electromagnetically induced transparency. Additional spectral and spatial tailoring can enable more complex structures including optical cavities that can be coupled to each other and to ensembles of atoms. Thus a fully reconfigurable cavity quantum electrodynamics system is formed without any fabricated structures, with the additional feature of dynamically switchable cavity mirrors. This scheme will enable dramatic improvement in the efficiency of rare-earth ensemble-based optical quantum memory to store photonic qubits. Rare-earth atoms are already one of the most promising platforms for quantum memory and coupling a rare-earth ensemble to an optical cavity addresses outstanding challenges related to making compact devices with long storage times without sacrificing storage efficiency. And doing so in a way that is reconfigurable without the need to fabricate a cavity makes this a flexible platform for a wide variety of useful quantum devices.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.