Semiconductor electron-nuclear spin qubits with optical access

非技术描述量子信息系统具有经典领域不可能实现的功能。这些系统依靠不同类型的量子位来执行不同的任务。例如，光子可用于量子通信，电子可用于量子计算，核自旋可用于量子存储器。一般来说，在不同类型的量子位之间传输信息是具有挑战性的。该研究项目将研究一种新兴的量子材料，即掺铟氧化锌，它有可能成为光子、电子和核量子位组合系统的基础。可以访问半导体平台中的核自旋存储器的单量子位隔离可能会导致可扩展的量子网络。这种网络可用于量子通信（一种从根本上安全的通信形式）和量子计算。此外，我们期望进一步了解供体的基本特性，从而影响大量半导体技术。该项目将为本科生和学生提供实验量子信息的研究培训。由于行业和政府对量子技术的大量投资，目前对量子劳动力培训的需求很高。技术描述晶体缺陷是用于量子网络应用的最先进的量子位平台之一。它们可能在单个系统中拥有 3 种类型的物理量子位：分别适用于量子存储、处理和通信的核自旋、电子自旋和光子。这项研究的重点是一种特别有前途的量子点缺陷，即氧化锌 (ZnO) 半导体基质中的浅铟供体。 In:ZnO 系统具有将高效光学接口和电子控制结合到可确定性创建的系统中的长期潜力。为此，该项目的目标是（1）在高纯 ZnO 中实现单施主隔离的高产率掺杂，以及（2）控制电子-核自旋界面，使量子存储器具有秒长存储的潜力。高度均匀的光学跃迁、接近1秒的纵向自旋弛豫时间、50微秒的量子存储时间、电子自旋量子位初始化和相干布居捕获都在供体：ZnO系统中实现。利用这种半导体系统实现量子技术仍然面临两个主要挑战：单供体隔离和核自旋控制。单供体分离的挑战是 ZnO 基底中的高供体密度。在这里，我们采用了一种基于通过分子束外延生长的超高纯度 ZnO、旨在选择性探测该层的光子制造以及单个/少数施主的注入的策略。在核自旋控制方面，该团队将开发实现光学核自旋泵浦、光学检测电子自旋共振和核自旋共振以访问铟核自旋9/2量子存储器的技术。该 PI 在扩大女性对 STEM 和量子信息的参与方面有着良好的记录，这一奖项将继续延续下去。最后，该活动将包括对威斯康星大学科学探索者项目的支持，该项目汇集了研究生志愿者、一名小学教师和小学生，在一所经济和种族多元化的西雅图一所公立学校进行科学和工程实验和活动。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智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL DESCRIPTIONQuantum information systems have capabilities not possible in the classical domain. These systems rely on different types of quantum bits, or qubits, to perform different tasks. For example, photons may be used for quantum communications, electrons for quantum calculations and nuclear spins for quantum memories. Generally, it is challenging to transfer information between different types of qubits. This research project will investigate an emerging quantum material, indium-doped zinc oxide, with the potential to serve as the basis for a combined photonic, electronic and nuclear qubit system. Single qubit isolation with access to a nuclear spin memory in a semiconductor platform could lead to scalable quantum networks. Such networks can be utilized for quantum communication, a form of fundamentally secure communication, and quantum computation. In addition, we expect further understanding of the fundamental properties of donors to impact a large set of semiconductor technologies. The project will provide research training in experimental quantum information to undergraduate and students. Quantum workforce training is currently in high demand due to the large industry and government investment in quantum technologies. TECHNICAL DESCRIPTIONDefects in crystals are one of the most advanced qubit platforms for quantum network applications. They may boast 3 types of physical qubits in a single system: nuclear spins, electron spins and photons suitable for quantum memory, processing and communication, respectively. This research focuses on a particular promising quantum point defect, the shallow indium donor in the zinc oxide (ZnO) semiconductor host. The In:ZnO system has the long-term potential to combine an efficient optical interface and electronic control in a system that can be deterministically created. Toward this end, the goal of this project is(1) to realize high yield doping with single donor isolation in high-purity ZnO and (2) control over the electron-nuclear spin interface to enable a quantum memory with potential for second-long storage. Highly homogeneous optical transitions, longitudinal spin-relaxation times approaching 1s, 50 microsecond quantum memory times, electron spin qubit initialization and coherent population trapping have all been realized in the donor:ZnO system. Two primary challenges remain to leverage this semiconductor system for quantum technologies: single donor isolation and nuclear spin control. The challenge in single donor isolation is the high donor density in ZnO substrates. Here, we employ a strategy based on ultra-high purity ZnO grown by molecular beam epitaxy, photonics fabrication designed to selectively probe this layer, and implantation of single/few donors. Toward nuclear spin control, the team will develop techniques to realize optical nuclear spin pumping, optically detected electron spin resonance and nuclear spin resonance to access the indium nuclear spin-9/2 quantum memory. The PI has a track record in broadening the participation of women in STEM and quantum information that will continue under this award. Finally, the activity will include support for the UW Science Explorers, which brings together graduate student volunteers, an elementary-school teacher, and elementary school students to conduct science and engineering experiments and activities at an economically and racially diverse Title 1 Seattle public school.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.