Mechanically Mediated Spin Entanglement in Diamond

钻石由碳原子的规则排列或晶格组成，通常在原子水平上含有缺陷。 常见的缺陷包括杂质，如氮或硅原子，以及空位-晶格中缺少原子的地方。 一种特殊的缺陷是“硅空位”中心，它由两个彼此相邻的空位组成，其间插入了一个硅原子。 一个电子可以被困在这样的缺陷周围，并被用作“量子比特”或“量子比特”--量子信息的基本单位。 使用这些量子比特来开发固态量子计算机的一个突出挑战是精确控制它们之间的相互作用。 该计划将开发一种实验方法，该方法使用金刚石薄膜中的机械振动来介导两个硅空位量子位之间的相互作用。 机械波可以方便地被限制和引导在一个适当设计的固态纳米结构中，而损耗可以忽略不计，这为量子信息技术的发展开辟了一个新的前沿。 此外，该项目还将为教育和人力资源做出贡献，为研究生和本科生提供科学和技术重要领域的优秀培训。该实验项目的重点是金刚石纳米机械谐振器中电子自旋之间的机械介导耦合，其长期目标是建立量子计算的类似捕获离子的固态平台。 该平台的主要构建块是金刚石兰姆波机械谐振器，其中硅空位中心中的电子自旋耦合到对称机械压缩模式。 兰姆波谐振器由声子晶体晶格保护，其可以实现仅受金刚石的固有材料损耗限制的机械Q因子。 利用硅空位中心的特殊能级结构的两种机制，将探讨自旋和机械振动之间的耦合。 一种是利用光学驱动的边带自旋跃迁。 另一种使用机械振动直接驱动自旋转变。 边带自旋跃迁将用于通过Molmer-Sorensen双量子位门的自旋纠缠，该门广泛用于捕获离子。 直接声学驱动将通过声子腔QED过程用于自旋纠缠。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。

Diamonds consist of a regular arrangement, or lattice, of carbon atoms, which often contains defects at the atomic level. Common defects include impurities, such as nitrogen or silicon atoms, and vacancies - places in the lattice where atoms are missing. A special defect is a “silicon-vacancy” center, which consists of two vacancies that are adjacent to each other, with a silicon atom inserted in between. An electron can be trapped around such a defect, and used as a “qubit,” or “quantum bit”—a fundamental unit of quantum information. An outstanding challenge for using these qubits to develop solid-state quantum computers is the precise control of the interactions between them. This program will develop an experimental approach that uses mechanical vibrations in an ultrathin diamond film to mediate interactions between two silicon-vacancy qubits. Mechanical waves can be conveniently confined and guided in a suitably designed solid-state nanostructure with negligible loss, opening up a new frontier in the development of quantum information technologies. In addition, this program will also make contributions to education and human resources by providing excellent training to graduate and undergraduate students in areas of both scientific and technological importance.This experimental program focuses on mechanically mediated coupling between electron spins in a diamond nanomechanical resonator, with the long-term goal of establishing a trapped-ion-like solid-state platform for quantum computing. The primary building block of this platform is a diamond Lamb wave mechanical resonator, in which electron spins in silicon vacancy centers couple to a symmetric mechanical compression mode. The Lamb wave resonator is protected by a phononic crystal lattice, which can enable the achievement of mechanical Q-factors limited only by the intrinsic material loss of diamond. Two mechanisms that take advantage of the special energy level structure of silicon vacancy centers will be explored for the coupling between spins and mechanical vibrations. One exploits optically driven sideband spin transitions. The other uses mechanical vibrations to directly drive spin transitions. The sideband spin transitions will be used for spin entanglement through a Molmer-Sorensen two-qubit gate, which is widely used for trapped ions. The direct acoustic driving will be used for spin entanglement via a phononic cavity QED process.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.