Cavity QED of Spins in Diamond via Dark States

摘要：在量子通信网络中，信息可以编码在包含单光子的光脉冲上。这种量子信息可以在包含单个原子（包括人造原子）的单个节点之间传播。网络中单光子和单原子之间的量子信息传输可以用来实现安全通信，并解决传统计算机难以解决的计算问题。这个实验项目旨在通过开发和使用一个实验平台来展示这种转移过程，在这个实验平台中，一个原本完美的金刚石晶体中的特殊缺陷中心被用作人造原子。单个缺陷中心与尺寸限制在小于50微米的光脉冲耦合。这种空间约束极大地增加了单光子产生的光强，从而增强了其与缺陷中心的耦合。一个特定的目标是通过这种增强的单光子耦合将量子信息从一个缺陷中心转移到另一个缺陷中心。该项目的研究活动也为研究生和本科生在纳米光子学和纳米制造以及量子科学与技术等领域提供了良好的培训机会。这种培训为学生在学术界、工业界或政府的职业生涯做准备。技术摘要：本项目致力于通过暗态控制单腔光子水平上的单自旋光学相互作用，暗态可以介导自旋和光子之间的可逆状态转移，同时规避自发发射等退相干过程。该项目开发并探索了一种复合腔量子电动力学（QED）系统，其中带负电荷的硅空位（SiV）中心位于100 nm厚的金刚石膜上，与硅微谐振器中光学低语廊模式的倏逝场耦合。该复合系统可以实现自旋态与腔模式的选择性耦合，并实现良好的腔限，其中腔线宽与单光子偶极子耦合率相比较小。电磁感应透明将用于探测和表征复合腔QED系统的暗态。然后，暗态将被用于自旋和光子之间的可逆态转移，研究腔QED系统的高能量阶梯态，以及两个SiV自旋之间的腔介导相干相互作用。该材料研究部（DMR）拨款支持研究了解复合腔量子电动力学（QED）系统，资金来自DMR的凝聚态物理（CMP）计划，物理部（PHY）的原子，分子和光学（AMO）计划以及数学和物理科学理事会的多学科活动办公室（OMA）。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知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Nontechnical Abstract:In a quantum communications network, information can be encoded on light pulses containing single photons. This quantum information can propagate between individual nodes containing single atoms, including artificial atoms. The transfer of quantum information between single photons and single atoms in the network can be exploited to implement secure communication and to solve computational problems that would otherwise be difficult with conventional computers. This experimental project aims to demonstrate this transfer process by developing and using an experimental platform, in which special defect centers in an otherwise perfect diamond crystal are used as artificial atoms. Single defect centers are coupled to light pulses that are confined in dimensions less than 50 micrometers. This spatial confinement greatly increases the light intensity that can be generated by a single photon and thus enhances its coupling to the defect center. A specific goal is to transfer quantum information from one defect center to another via this enhanced coupling to single photons. Research activities of this project also provide excellent training opportunities for graduate and undergraduate students in areas including nanophotonics and nanofabrication as well as quantum science and technology. This training prepares the students for careers in academia, industry, or government. Technical Abstract:This project focuses on controlling optical interactions of a single spin at the level of single cavity photons via a dark state, which can mediate reversible state transfers between spins and photons, while circumventing decoherence processes such as spontaneous emission. The project develops and explores a composite cavity quantum electrodynamics (QED) system, in which negatively charged silicon vacancy (SiV) centers in a 100 nm thick diamond membrane couple to evanescent fields of optical whispering gallery modes in a silica microresonator. The composite system can enable spin-state selective coupling to the cavity mode as well as the realization of the good cavity limit, in which the cavity linewidth is small compared with the single-photon dipole coupling rate. Electromagnetically induced transparency will be used to probe and characterize the dark state of the composite cavity QED system. The dark state will then be exploited for reversible state transfers between spins and photons, studies of higher energy ladder states of the cavity QED system, and cavity-mediated coherent interactions between two SiV spins.This Division of Materials Research (DMR) grant supports research to understand composite cavity quantum electrodynamics (QED) systems with funding from the Condensed Matter Physics (CMP) program in DMR, the Atomic, Molecular, and Optics (AMO) program in the Division of Physics (PHY), and the Office of Multidisciplinary Activities (OMA) of the Mathematical and Physical Sciences Directorate.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.