A Chip-scale Quantum Information Processor Using Atomic Ions and Photonic Circuits

摘要标题：一个使用原子离子和光子电路的芯片级量子信息处理器在复杂量子系统的经典模拟的困难、与加密有关的算法的执行和某些搜索问题的驱动下，量子态工程近年来被证明是一个卓有成效的领域。原子离子是发展量子信息处理器的主要途径。通常情况下，由于依赖于在自由空间中传播的光束来控制和读出离子，所以实验仅限于少数几个离子。通常光学方法的困难对近年来发展起来的有前途的基本思想的有效应用构成了巨大的障碍。这项工作旨在设计纳米光子设备和系统，其中光在芯片上以允许数千个独立光束的方式进行控制，这些光束可以与限制芯片上方离子的电极结构集成在一起。这项工作将导致对单个离子的光学控制和读出，其规模比目前的技术大得多；此外，拟议的集成将带来某些性能优势，包括由于更紧密地聚焦于单个离子而对激光光束的功率要求更低，以及由于光束的相位和相对于离子的位置的稳定性而降低噪声。这种方法将提高集成光子学领域的基本能力，并更接近在原子系统中进行任意量子状态操纵的目标，这些原子系统足够大，可以探索物理，以及进行有用的计算，而不是在目前的经典计算机上可以完成的工作。要实现所提出的系统，需要开发各种基本的光子器件，以及实现系统的方法。感兴趣的离子具有跨越可见光光谱的跃迁(对于88Sr+，422-1097 nm)，如果在相同的介质层中以低损耗引导所有波长，则该方法的影响最大。将开发一种光栅耦合器，将在单模介质波导中传播的光转换为向离子传播的聚焦光束。还将设计和制造以集成非线性材料作为有源核心材料的电光器件，用于对用于量子比特控制和读出的光束进行高消光(40分贝)调制。此外，我们还将寻求一种后处理技术，利用这种技术，可以在标准的cmos铸造厂制造的芯片中创建这样的设备；这将使系统有可能将波束形成光学器件、调制器和雪崩光电探测器与陷阱电极和控制电子设备结合在一起，以控制前所未有的囚禁离子系统。作为科学和工程研究平台的CMOS制芯片的一个关键优势是实验设备固有的重复性和易传播性。原子物理和可见光子学的学生将第一次能够利用CMOS数十亿美元的基础设施。通过深入借鉴集成光子学和原子物理学的思想，这项工作还为参与其中的本科生、研究生和研究人员创造了跨学科教育和合作的新机会；除了这里提出的工作提供的囚禁离子系统的能力外，我们预计这两个领域之间的交叉培养将为无法预见的想法创造肥沃的土壤。

Abstract Title: A Chip-scale Quantum Information Processor Using Atomic Ions and Photonic CircuitsDriven by the intractability of classical simulation of complex quantum systems, the execution of algorithms pertaining to encryption and certain search problems, quantum state engineering has proven a fruitful field in recent years. Atomic ions are a leading approach to development of quantum information processors. Typically experiments have been limited to a few ions because of the reliance on optical beams propagating in free space for control and readout of the ions. Difficulties with the usual optics approach pose formidable barriers to the useful application of the wealth of promising basic ideas that have been developed in recent years. This work seeks to devise nanophotonic devices and systems in which light is controlled on chip in a fashion allowing thousands of independent optical beams, which can be integrated with electrode structures that confine the ions above the chip. The work would lead to optical control and readout of individual ions at dramatically larger scales than possible with current technology; additionally, integration as proposed would bring certain performance advantages, including lower power requirements on the laser beams due to tighter focusing on individual ions, and reduced noise due to stability of the beams' phase and location with respect to ions. The approach would advance basic capabilities in the field of integrated photonics, and bring closer the goals of arbitrary quantum state manipulation in atomic systems large enough to allow exploration of physics, as well as useful computations, beyond what can be done on current classical computers. Realizing the systems proposed requires developments in a variety of basic photonic devices, and approaches to systems implementations. Ions of interest have transitions spanning the visible spectrum (for 88Sr+, 422-1097 nm), and the impact of the approach is greatest if all wavelengths are guided with low loss in the same dielectric layer. Grating couplers will be developed that convert light propagating in single-mode dielectric waveguides into focused beams propagating towards the ions. Electro-optic devices using integrated non-linear materials as the active core material for high-extinction (40 dB) modulation of beams used for qubit control and readout will be designed and fabricated as well. In addition, we will pursue a post-processing technique whereby devices such as these could be created in chips made in standard CMOS foundries; this would open the possibility for systems bringing together beam-forming optics, modulators and avalanche photodetectors together with trap electrodes and control electronics for control of trapped ion systems with unprecedented scale. A critical advantage of CMOS foundry-made chips as a platform for science and engineering research is the intrinsic reproducibility and ease of dissemination for the experimental devices. For the first time, students of atomic physics and visible photonics will be able to leverage the multi-billion dollar infrastructure of CMOS. By drawing deeply on ideas both in integrated photonics and atomic physics, this work additionally creates new opportunities for interdisciplinary education and collaboration for the undergraduates, graduate students and researchers involved; and in addition to the capabilities for trapped ion systems offered by the work proposed here, we expect cross-fertilization between the two areas will make fertile ground for unforeseen ideas.