Qubits in isotopically enriched 28Si

同位素富集 28Si 中的量子位

• 批准号: 496720564
• 负责人: Professor Dr. Michael Oestreich
• 金额: --
• 依托单位: Institut für Festkörperphysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/496720564?language=en
• 关键词: Qubits; isotopically; enriched; 28Si

Isotopically enriched 28Si is a fascinating material system for spin-based quantum devices. Electron and nuclear qubits using shallow donors in phosphorous doped 28Si offer extremely long spin relaxation and dephasing times and are thereby among the most promising candidates for a semiconductor quantum information technology. One of the major challenges of quantum logic in 28Si:P is of course the electron and nuclear spin initialization which has been achieved by Yang et al. by selective optical pumping of the phosphorous donor transitions. The linewidths of these optical transitions are among the narrowest linewidths of shallow donor ensembles in semiconductors and the experimentally demonstrated degree of optical spin initialization is rather high. However, the degree of spin polarization is well below the desirable 100 % so far which is most likely linked to the observation of spectral holes burned into the donor transitions.The first goal of this proposal is a profound understanding of the non-trivial physics of this hole burning dynamics. The group of Thewalt observed in continuous wave experiments minimal hole burning linewidths which are a factor of four larger than calculated from the donor bound trion recombination time. The cause is unknown but might be attributed to a combination of (a) interaction with optically excited free electrons and holes, (b) fluctuating internal electric fields due to unavoidable, unintentional, p-type background doping, and (c) electron-electron interaction. We will apply a special time-resolved pump-probe absorption setup to determine quantitatively the different contributions and use this information (a) to optimize the optically induced spin polarization to well above 99% and (b) to write energetically separated spin sub-ensembles into the donor bound electron ensemble. The second goal of this proposal is entanglement of macroscopic donor spin ensembles. We will use the optimized spin initialization and write two, spatially separated, macroscopic spin ensembles into a high quality 28Si sample. Afterwards, we entangle these spin ensembles by an optical pulse and verify the entanglement by a spin noise like technique. Entanglement of a donor-bound electron spin ensemble with the respective nuclear spin ensemble has been demonstrated before but entanglement of spatially separated macroscopic donor electron spin ensembles has not been established in 28Si so far, to the best of our knowledge.Phosphorous donors in 28Si are excellent candidates for qubits but single optical defects which are isolated and bright and emitting at identical wavelengths in the telecom bands would enable additionally the implementation of scalable silicon quantum photonics. Very recent experiments on carbon implanted Si report on such single photon emitter but with strongly varying wavelengths. The search for single photon emitters with identical wavelengths in high quality 28Si will be the third task of this proposal.

同位素富集的 28Si 是一种用于自旋量子器件的令人着迷的材料系统。在磷掺杂 28Si 中使用浅施主的电子和核量子位可提供极长的自旋弛豫和相移时间，因此是半导体量子信息技术最有前途的候选者之一。 28Si:P 量子逻辑的主要挑战之一当然是电子和核自旋初始化，这已由 Yang 等人实现。通过磷供体跃迁的选择性光泵浦。这些光学跃迁的线宽是半导体中浅施主系综的最窄线宽之一，并且实验证明的光学自旋初始化程度相当高。然而，自旋极化程度远低于迄今为止理想的 100%，这很可能与观察到供体跃迁中燃烧的光谱空穴有关。该提案的第一个目标是深刻理解这种空穴燃烧动力学的重要物理原理。 Thewalt 小组在连续波实验中观察到最小烧孔线宽，该线宽比根据供体结合 Trion 重组时间计算出的线宽大四倍。原因尚不清楚，但可能归因于 (a) 与光激发自由电子和空穴的相互作用，(b) 由于不可避免的、无意的 p 型背景掺杂而导致的内部电场波动，以及 (c) 电子-电子相互作用。我们将应用特殊的时间分辨泵浦探针吸收装置来定量确定不同的贡献，并使用此信息（a）将光致自旋极化优化至远高于 99％，以及（b）将能量分离的自旋子系综写入供体束缚电子系综中。该提案的第二个目标是宏观供体自旋系综的纠缠。我们将使用优化的自旋初始化并将两个空间分离的宏观自旋系综写入高质量的 28Si 样本中。 之后，我们通过光脉冲使这些自旋系综纠缠，并通过自旋噪声等技术验证纠缠。供体束缚电子自旋系综与相应核自旋系综的纠缠之前已被证明，但据我们所知，迄今为止，空间分离的宏观供体电子自旋系综的纠缠尚未在 28Si 中建立。28Si 中的磷供体是量子位的绝佳候选者，但孤立且明亮且在电信频段中以相同波长发射的单一光学缺陷将 另外还可以实现可扩展的硅量子光子学。最近关于碳注入硅的实验报告了这种单光子发射器，但波长变化很大。在高质量 28Si 中寻找具有相同波长的单光子发射器将是该提案的第三个任务。