CQIS: Coherent Spin-Phonon Interfaces with Diamond Color Centers

第一部分：量子科学和技术有望实现强大的计算机和安全的互联网，这两者共同导致前所未有的分布式量子计算资源的发展。为了实现这一目标，必须开发包括许多耦合量子位（qubit）的系统，这些量子位具有执行存储、通信和多量子位逻辑操作的能力。钻石中的原子级发光缺陷-色心-最近已经成为具有许多这些特征的领先固态平台。然而，使用光有效地耦合不同色心的方法受到光子损失的限制。这在很大程度上是由于将光限制在金刚石芯片上的亚微米体积的困难。该计划将探索依赖于机械振动的量子位耦合的替代方法，从而为量子科学和技术领域带来新一代的能力，并应用于量子信息处理和量子计量学。该计划涉及与量子工程，量子信息科学，纳米纤维，材料科学，纳米光子学和纳米力学相关的主题，具有很强的理论和实验成分。因此，它为各级学生提供了独特的研究和教育机会。 第二部分：金刚石中的原子级发光缺陷最近成为实现片上量子网络的领先固态平台。特别重要的是带负电荷的氮空位（NV）和硅空位（SiV）色心，它们拥有量子技术的所有基本元素：存储，控制和读出。虽然NV仍然是最好的固态量子存储器，但最近的工作表明，SiV是具有光谱稳定和类原子发射的上级量子发射体。此外，已经证明可以通过施加由机械运动引起的应变来设计SiV特性。在该计划中，SiV中的强自旋-应变耦合将被用来实现量子网络，该网络利用声学声子作为片上量子网络中的信息载体。例如，通过将SiV嵌入声子腔和波导内，将有可能设计自旋-声子相互作用并通过SiV实现受控的声子发射和吸收，以及声子路由，存储和声子-声子相互作用（声子开关）。这将使基于嵌入机械谐振器内的SiV的双量子比特量子门的实现成为可能，其中量子比特纠缠由机械振动介导。另一方面，通过用声子带隙结构包围SiV，声子发射过程将被抑制，从而将SiV的自旋相干时间提高几个数量级。该计划将为量子声学动力学的新领域铺平道路，该领域使用声子和一般的机械振动作为芯片上的信息载体。重要的是，由于机械振动可以被设计成与许多不同的量子比特（自旋、电荷、通量、光子）相干耦合，因此所提出的努力可能使量子态在不同自由度之间转移，并导致实现混合量子网络。该奖项反映了NSF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。

Part 1: Quantum science and technology promise the realization of powerful computers and a secure internet, which together could lead to the development of unprecedented distributed quantum computational resources. To achieve this goal, the development of systems comprising many coupled quantum bits (qubits) with the ability to perform storage, communication and multi-qubit logic operations is essential. Atomic-scale luminescent defects - color centers - in diamond have recently emerged as a leading solid-state platform that has many of these characteristics. However, approaches to efficiently couple different color centers using light have been limited by a photon loss. This is largely due to the difficulties associated with confining light to a sub-micron volume on a diamond chip. The proposed program will explore an alternative approach to qubit coupling that relies on mechanical vibrations, and will thus enable a new generation of capabilities for the field of quantum science and technology, with applications in quantum information processing and quantum metrology. The program addresses topics related to quantum engineering, quantum information science, nanofabrication, material science, nanophotonics and nanomechanics and has strong theoretical and experimental component. Therefore, it represents a unique research and educational opportunity for students at all levels. Part 2: Atomic-scale luminescent defects in diamond have recently emerged as a leading solid-state platform for realization of on-chip quantum networks. Of particular importance are negatively charged nitrogen-vacancy (NV) and silicon-vacancy (SiV) color centers that possess all the essential elements for quantum technology: storage, control and read-out. While the NV remains the best solid state quantum memory, recent work has shown that SiV is superior quantum emitter with spectrally stable and atomic-like emission. Furthermore, it has been demonstrated that SiV properties can be engineered by applying strain, induced by mechanical motion. In this program, strong spin-strain coupling in SiV will be leveraged to realize quantum networks that utilize acoustic phonons as information carriers in on-chip quantum networks. For example, by embedding SiVs inside phononic cavities and waveguides, it will be possible to engineer spin-phonon interactions and achieve controlled phonon emission and absorption by SiVs, as well as phonon routing, storage, and phonon-phonon interactions (phonon switches). This will enable realization of two-qubit quantum gates based on SiVs embedded inside mechanical resonators, in which qubit entanglement is mediated by mechanical vibration. On the other hand, by surrounding SiV with a phononic bandgap structures, phonon emission process will be suppressed thus enhancing the SiV spin coherence time by several orders of magnitude. The proposed program will pave the way for a new field of quantum acousto dyanmics that uses phonons, and mechanical vibration in general, as on-chip information carriers. Importantly, since mechanical vibrations can be engineered to couple coherently to many different qubits (spin, charge, flux, photon), proposed efforts may enable transfer of quantum states between different degrees of freedom, and lead to realization of hybrid quantum networks.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.