Toward a Large-Scale Superconducting Quantum Computer: Error Management and Scalability

实用的量子计算机比以往任何时候都更接近现实。在许多实现中，捕获离子、半导体器件和超导量子电路是最有希望实现约100-100000量子比特的中型和大规模量子计算机的候选者。超导量子比特已经集成到~50个量子比特的阵列中，并且原则上可以进一步集成。然而，由于材料不完善或工程不充分而导致的耗散现象可能导致量子位失效，并且迄今为止仍然是一个主要挑战。此外，从中型到大型系统的转变将需要真正可扩展的经典量子比特布线和控制技术，而这些技术目前还无法实现。在过去的五年里，致力于实用量子计算机的社区发生了巨大的变化。IBM和b谷歌等大型企业正在投资数亿美元来改进和扩大量子比特阵列。为了具有竞争力，临床研究计划的选择势在必行。以经典集成电路产业为例。大型企业建立一个完整的计算平台所需的硬件和软件；研究实验室调查开放的科学和技术挑战，并找到解决方案，然后被大公司采用。我的研究计划的长期愿景是减少量子比特错误，并为大型量子计算机开发可扩展的技术。两个主要目标是：1)误差管理：a.通过集成一种新型超导电路：口袋囊谐振器来消除由于材料不完美而导致的耗散。实现一个新的量子位：口袋币量子位。2)可扩展性：a.为大规模量子计算机开发一种新的量子比特布线技术：用于完全垂直互连的引脚芯片连接。b.基准引脚芯片与量子位键合。超导片上器件的材料缺陷是由于在量子比特附近存在氧化层。pocketmon量子比特是一种新型的超导装置，我们不是去除氧化层，而是将量子比特的能量存储在一个空间区域，这个区域只受不需要的层的轻微影响。Pin-chip键合是我发明的一种新型量子比特布线技术。这项技术使得操作超过100000个量子比特的二维数组成为可能，允许从上方到达数组中的任何量子比特，而不是像目前使用传统技术那样横向到达。如果一个方形芯片包含NxN个量子位，从上面访问量子位可以让我们从侧面获得N2个量子位，而不是仅仅4N个量子位。加拿大，特别是滑铁卢，已经建立了一个强大的“量子生态系统”。我的研究计划旨在加强这方面的努力，朝着实用量子计算技术的方向发展。这将产生一个强大的高技能的加拿大学生在一个快速发展的研究领域的专业知识。

Practical quantum computers are closer to reality than ever before. Among many implementations, trapped ions, semiconducting devices, and superconducting quantum circuits are among the most promising candidates to implement medium- and large-scale quantum computers with ~100-100000 qubits. Superconducting qubits have already been integrated in arrays of ~50 qubits and can in principle be further integrated. However, dissipation phenomena due to imperfect materials or inadequate engineering can cause a qubit to fail and, to date, continue to be a major challenge. Additionally, moving from medium- to large-scale systems will require truly scalable classical qubit wiring and control techniques that are not yet available. The community working on practical quantum computers has evolved dramatically in the last five years. Major ventures such as IBM and Google are investing hundreds of millions of dollars to improve and scale up qubit arrays. In order to be competitive, it is imperative to choose a research plan clinically. The classical integrated circuit industry should serve as an example. Major ventures build the hardware and software required for a complete computing platform; research labs investigate the open scientific and technological challenges and find solutions that are then adopted by the large companies. The long-term vision of my research program is to reduce qubit errors and develop scalable technologies for a large-scale quantum computer. The two main objectives are: O1)Error management: a.Banish dissipation due to imperfect materials by integrating a novel superconducting circuit: The pocketmon resonator. b.Realize a new qubit: The pocketmon qubit. O2)Scalability: a.Develop a new qubit wiring technique for a large-scale quantum computer: Pin-chip bonding for fully vertical interconnects. b.Benchmark pin-chip bonding with qubits. Material imperfections in superconducting on-chip devices are due to the presence of oxidized layers in proximity of the qubits. The pocketmon qubit is a new type of superconducting device where, instead of removing the oxidized layers, we store the qubit energy in a region of space that is only marginally affected by the unwanted layers. Pin-chip bonding is a novel qubit wiring technique that I invented. This technique makes it possible to operate two-dimensional arrays with more than 100000 qubits, permitting to reach any qubit in the array from above instead of laterally, as presently done with traditional techniques. If a square chip contains NxN qubits, accessing the qubits from above allows us to reach N2 qubits instead of just 4N qubits from the sides. Canada in general and, in particular, Waterloo have already created a strong "quantum ecosystem." My research program aims at strengthening this effort in the direction of practical quantum computing technologies. This will generate a strong class of highly skilled Canadian students with expertise in a rapidly blooming field of research.