Quantum Control of Vanadium Nuclear Spin Registers Surrounding a Single Ytterbium Ion in a Crystal

在单原子或类原子系统与环境相互作用的水平上理解和控制固态量子系统是科学研究的前沿，因为它为了解固态中最基本的量子相互作用提供了一个窗口。近年来，人们研究了多种嵌在固体中的原子，包括元素周期表中镧系元素系列中的元素，也被称为稀土。在这项工作中，该小组将研究在正钒酸钇晶体中单个钇原子与附近钒核之间的相互作用。原子核可以作为量子信息的局部存储元素。它们可以用来创建未来的光量子网络，从而实现高安全性的信息传输。该项目开发的技术也可用于与量子传感和量子计算相关的未来协议。量子技术有望帮助整个社会，因为它们可能导致通信安全、计算和传感方面的实质性改进。该项目将提供培训研究生的机会，这些研究生将构成未来量子产业的劳动力。通过测量与纳米光子谐振器耦合的镱原子，研究了镱与附近原子核的相互作用。该小组已经描述了这种相互作用的哈密顿量，开发了使原子核极化的技术，并将镱量子比特的量子态存储/检索到钒系综中。局域自旋综以相同的方式围绕着每个镱量子比特，从而为量子技术提供了高度通用的资源。在这项工作中，该小组将采用动态哈密顿工程来探索钒自旋的增强量子控制，包括创建核格林伯格-霍恩-塞林格（GHZ）态，钒核自旋激发的数字解析测量以及在寄存器中存储多个量子激发。通过射频场直接驱动核自旋将被实现，从而导致内存存储时间的增加，这对于未来量子中继网络的实现是必要的。这是对这种类型的量子系统的首次探索，它为晶体中密集核自旋的量子多体物理提供了新的见解。这项研究的影响是多方面的。一方面，它具有纯粹的科学价值，因为它允许研究和控制单个量子比特与密集但离散的核自旋系综之间的量子相互作用的新制度。另一方面，控制这种量子相互作用可以实现本地量子存储器寄存器，这对于实现量子机器非常重要，例如用于远程量子网络的量子中继器，这些量子中继器将用于连接未来的量子计算机和建立安全的量子通信。量子技术被视为美国战略性科学发展的一个领域，并在国家量子倡议的背景下积极追求。预计量子技术将对计算和通信产生深远的影响，从而引发下一次技术革命。本研究中专门针对正钒酸钇中的镱开发的技术可以扩展到其他量子系统。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。

Understanding and controlling solid state quantum systems at the level of single atoms, or atom-like systems, interacting with their environment is at the forefront of scientific research as it provides a window into the most fundamental quantum interactions in solid state. In recent years, multiple types of atoms embedded in solids have been studied, including elements in the lanthanide series of the periodic table, also known as rare earths. In this work, the group will study the interaction between single ytterbium atoms and the nearby vanadium nuclei in an yttrium orthovanadate crystal. The nuclei can act as a local memory element for quantum information. They could be utilized to create future optical quantum networks that could lead to transmitting information with high security. The techniques developed in the project may also be utilized for future protocols relevant for quantum sensing and quantum computing. Quantum technologies are expected to help the society at large as they may lead to substantial improvements in communication security, computing and sensing. This project will provide the opportunity to train graduate students that will constitute the workforce in a future quantum industry.The interaction between the ytterbium and the nearby nuclei will be studied by measuring the ytterbium atom that is coupled to nano-photonic resonators. The group has already characterized the Hamiltonian of this interaction, developed techniques to polarize the nuclei and stored/retrieved the quantum state of the ytterbium qubit into/from the vanadium ensemble. The localized spin ensemble surrounds every ytterbium qubit in an identical manner, thus providing a highly versatile resource for quantum technologies. In this work the group will employ dynamic Hamiltonian engineering to explore augmented quantum control of the vanadium spins including the creation of nuclear Greenberger–Horne–Zeilinger (GHZ) states, number-resolving measurements of the vanadium nuclear spin excitations and storing multiple quantum excitations in the register. Direct driving of the nuclear spins via radio frequency fields will be realized, leading to increased memory storage time, which is necessary for future implementations of quantum repeater networks. This is the first exploration of a quantum system of this type, which provides new insights into the quantum many body physics of dense nuclear spins in a crystal. The impact of this research is multi-faceted. On one side, it has pure scientific value as it allows for studying and controlling the new regime of quantum interaction between a single qubit and a dense but discrete nuclear spin ensemble. On another side, controlling this quantum interaction enables local quantum memory registers that are very important for implementing quantum machines like quantum repeaters for long distance quantum networks that will be utilized in interconnecting future quantum computers and establishing secure quantum communications. Quantum technologies are seen as an area of strategic scientific growth for the United States and are aggressively pursued under the context of the National Quantum Initiative. It is expected that quantum technologies will impact computing and communications in a profound way that will lead to the next technological revolution. The techniques developed in this research specifically for ytterbium in yttrium orthovanadate can be extended to other quantum 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.