CQIS: Coherent Spin-Phonon Interfaces with Diamond Color Centers

第一部分：量子科学和技术承诺实现强大的计算机和安全的互联网，这两者共同可能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，开发具有存储、通信和多量子位逻辑运算能力的多个耦合量子比特(量子比特)的系统是必不可少的。最近，钻石中的原子尺度发光缺陷--色心--已经成为一种领先的固态平台，具有许多这些特征。然而，利用光有效地耦合不同颜色中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钻石芯片上的亚微米体积相关的困难。拟议的计划将探索一种依赖机械振动的量子比特耦合的替代方法，从而为量子科学和技术领域带来新一代能力，并在量子信息处理和量子计量学中得到应用。该计划涉及量子工程、量子信息科学、纳米制造、材料科学、纳米光子学和纳米力学等主题，具有很强的理论和实验成分。因此，它为各级学生提供了一个独特的研究和教育机会。第二部分：金刚石中的原子尺度发光缺陷最近成为实现片上量子网络的主要固态平台。尤其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，但最近的研究表明，SIV是具有光谱稳定性和原子样发射的优越量子发射器。此外，已经证明，可以通过施加机械运动引起的应变来改变SIV的性能。在该计划中，将利用SIV中的强自旋应变耦合来实现利用声学声子作为片上量子网络中的信息载体的量子网络。例如，通过在声子腔和波导中嵌入SIV，将有可能设计自旋-声子相互作用，并实现SIV控制的声子发射和吸收，以及声子路由、存储和声子-声子相互作用(声子开关)。这将使基于嵌入在机械谐振器中的SIV实现两量子比特量子门成为可能，其中量子比特纠缠通过机械振动来中介。另一方面，通过声子禁带结构包围SIV，声子发射过程将被抑制，从而使SIV的自旋相干时间提高几个数量级。拟议的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、磁通、光子)相干耦合，所提出的努力可能会使不同自由度之间的量子态转移成为可能，并导致混合量子网络的实现。这一奖项反映了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。

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.