CAREER: Mechanical Control of Single Spins for Sensing and Quantum Information Processing

这个职业项目是由电子和光子材料计划以及凝聚态物理计划共同资助的。非技术：随着纳米级材料加工的进步，现在有可能形成表现出量子力学效应的宏观机械装置，这种行为通常只在原子尺度的系统中观察到。这个职业项目建立在这些进展的基础上，探索数十亿个原子一致运动的宏观运动(声子)和一个微小的量子物体(单电子自旋)之间的基本相互作用。单自旋是钻石中的氮空位中心：一种具有原子性质的模型量子系统，可以唯一地访问和控制。氮空位中心具有极高的灵敏度，可以作为自旋-机械耦合的纳米级量子探针；此外，利用这种耦合可以推动量子计量学和量子信息处理的进步。最后，这两个存在于巨大不同大小尺度上的系统的并列使得宏观量子力学和量子世界与经典世界交界处的消相干得以基本探索。这项研究与一项强有力的教育计划紧密结合在一起，该计划专注于培养不同背景的学生对科学的热情，通过创新思维和奉献精神让他们做好应对国家挑战的准备。首席调查员(PI)积极地让本科生，特别是女性和社区大学的学生在她的实验室里工作，并在他们接受高等教育的多年中确立了自己作为正式导师的地位。PI与UCSB科学思想学校合作，在该学校，研究生向来自不同背景的高中生教授周六的课程，向更广泛的受众传播研究发现。技术：这个项目调查了单个高度相干的自旋和宏观机械自由度是如何相互作用的，这种相互作用对自旋的量子行为有什么影响，以及自旋和声子是否可以在功能上集成。含氮空位(NV)中心的单晶金刚石悬臂梁是研究自旋-机械耦合的一种新平台。悬臂的运动产生了大范围的应变场，其大小和方向都得到了精确控制。利用单个NV中心作为量子纳米尺度的传感器测量应变耦合系数，其结果将指导对相关基态自旋相互作用的更完整的理论处理。通过应变调谐提高了NV磁敏感度。为了测量各种起伏的场，研究了基于自旋弛豫的新型量子传感技术。通过工程金刚石生长和纳米深度控制，形成了含有长自旋相干时间(约10ms)的纳米V的高质量因子纳米机械谐振器。结合这一优异的力学和自旋性质，我们探索了自旋-声子耦合和声子介导的自旋-自旋相互作用的量子机制。

This CAREER project is co-funded by the Electronic and Photonic Materials Program and the Condensed Matter Physics Program.Non-technical: With advances in materials processing at the nanoscale, it is now possible to form macroscopic mechanical devices that exhibit quantum mechanical effects, behavior typically observed only in atomic-scale systems. This CAREER project builds on these advances to probe the fundamental interactions between the macroscopic motion of billions of atoms moving in unison, a phonon, and a miniscule quantum object, a single electron spin. The single spin is a nitrogen-vacancy center in diamond: a model quantum system with atom-like properties that are uniquely accessible and controllable. With its exquisite sensitivity, the nitrogen-vacancy center can be used as nanoscale quantum probe of spin-mechanical coupling; furthermore, harnessing this coupling could enable advances in quantum metrology and quantum information processing. Finally this juxtaposition of two systems existing at vastly different size scales enables fundamental explorations of macroscopic quantum mechanics and decoherence at the interface of quantum and classical worlds. This research is tightly coupled with a strong educational plan focusing on cultivating a passion for science in students of varied backgrounds by preparing them to attack the nation's challenges through innovative thinking and dedication. The Principle Investigator (PI) actively involves undergraduates, especially women and community college students, in her laboratory and establishes herself as a formal mentor throughout the years in their higher education. The PI partners with the UCSB School for Scientific Thought, in which graduate students teach Saturday classes to high-school students from diverse backgrounds, disseminating research discoveries to a wider audience. Technical: This project investigates how a single highly coherent spin and a macroscopic mechanical degree of freedom interact, what implications the interaction has for the quantum behavior of the spin, and whether spins and phonons can be functionally integrated. Single-crystal diamond cantilevers with embedded nitrogen vacancy (NV) centers are a novel platform to study spin-mechanical coupling. Motion of the cantilever generates large-amplitude strain fields with precisely controlled magnitude and direction. Single NV centers are used as quantum nanoscale sensors to measure the strain coupling coefficients and the results will guide a more complete theoretical treatment of the relevant ground-state spin interactions. Enhanced NV magnetic sensitivity is explored through strain tuning. Novel quantum sensing techniques based on spin relaxation are investigated in order to measure fluctuating fields of various origins. High quality-factor nanomechanical resonators containing NVs with long spin coherence times (about 10 ms) are formed via engineered diamond growth with nanoscale depth control of NVs. With this combination of excellent mechanical and spin properties, the quantum regime of spin-phonon coupling and phonon-mediated spin-spin interactions are explored.