Quantum: Microarchitectures for Quantum Computers

如果大规模量子计算机今天存在，它将深刻影响几乎所有科学和工程领域。它将极大地加速新材料和新药物的开发，从而产生广泛的影响。它将提供新的安全通信基础设施。目前，只有小规模的原型量子计算机存在，并且在将这些设备扩展到足够大的尺寸以产生有意义的实际结果方面存在巨大的挑战。生产大规模量子计算机是我们国家和世界的一个非常重要的目标。这将需要科学和工程几个学科的共同努力，包括物理、材料、控制、计算机科学和计算机工程。该提案资助了量子计算机工程方面的工作，特别是此类设备的微架构。离子阱量子计算机的微结构显著地改变了它的性能。一个糟糕的微架构具有有限的科学价值，因为它无法正确计算量子算法的结果。一个好的微架构不仅能正常工作，还能揭示如何构建更大、更可扩展的设计。研究量子计算机的微结构需要工具。量子算法可以由数十亿个操作组成。大规模量子微架构的建议由数千个离散元素组成。手工研究如何将这数十亿个操作中的每一个操作的执行映射到数千个可用组件上是不实际的。相反，执行这种映射的自动化工具对于此类计算机系统的有用研究是必需的。这项工作的智力价值在于，它通过专注于这种工具的开发，精确地研究了如何构建真正的大规模量子计算机。特别是，我们之前的工作为基于离子阱的量子计算机开发了所谓的计算机辅助设计（CAD）工具套件。使用这些CAD工具，我们展示了构建量子计算机的难度要大得多。该提案为这些CAD工具的持续研究提供了资金。由该提案资助的特定工具开发如下：在编码方案中实现更多样化，对CAD工具套件核心的调度机制进行彻底检查，以及开发一组CAD单元，用于有效地计算量子软件中经常出现的执行模式。实现更多的纠错编码方案将使量子计算机架构师能够研究编码效率，并将编码方案专门用于最适合的设备区域。更新调度器将能够更好地利用并行性（一次做多件事）和局部性（在物理空间中使操作靠近在一起，以尽量减少移动它们所需的时间）。最后，CAD单元的开发将使我们能够将完全定制设计的组件合并到整个CAD框架中，从而利用这些努力获得更多的时间和面积效率高的组件。我们的研究目标是，通过这些技术的结合，我们可以减少我们在构建大型量子计算机时面临的挑战，从而使这样的设备能够更快地构建。

If a large-scale quantum computer existed today, it would profoundly impact almost every area of science and engineering. It would have broad impact by dramatically speeding up the development of new materials and medicines. It would provide new secure communication infrastructure. Currently, only small-scale prototype quantum computers exist, and enormous challenges exist in scaling these devices to sizes large enough to produce meaningful practical results. Producing a large-scale quantum computer is a profoundly important goal for our nation and the world to undertake. It will require a combined effort of several disciplines of science and engineering, including, physics, materials, controls, computer science and computer engineering. This proposal funds work on the engineering of quantum computers, specifically the microarchitecture of such devices. The microarchitecture of an ion-trap quantum computer significantly alters its capabilities. A poor microarchitecture has limited scientific value because it is unable to correctly compute the result of quantum algorithms. A good microarchitecture not only functions properly, but also reveals insights about how to build ever larger and more scalable designs.To study the microarchitecture of a quantum computer tools are required. Quantum algorithms can consist of billions of operations. Proposals for large-scale quantum microarchitectures consist of thousands of discrete elements. It is not practical to study by hand how to map execution of every one of these billions of operations onto the thousands of available components. Instead, automated tools that perform this mapping are required for the useful study of such computer systems.The intellectual merit of this work is that it studies precisely how to build a real large-scale quantum computer by focusing on such tool development. In particular, our prior work developed what is termed a computer-aided-design (CAD) suite of tools for ion-trap based quantum computers. Using these CAD tools we demonstrated the orders of magnitude more difficult challenge building a quantum computer will be. This proposal funds continued research on these CAD tools.The particular tool development funded by this proposal is the following: implementation of more variety in the coding schemes, an overhaul of the scheduling mechanism at the heart of the CAD tool suite, and development of a collection of CAD-cells, for efficiently computing often appearing patterns of execution in quantum software. Implementing more error correction coding schemes will enable quantum computer architects to study code efficiency and specialize the coding schemes to the areas of a device where they are best suited. Updating the scheduler will enable better exploitation of parallelism (doing more than one thing at a time) and locality (having operations close together in physical space, as to minimize the time required to move them around). Finally, development of CAD cells will enable us to merge fully custom designed components into the overall CAD framework, thereby leveraging such efforts for more time and area-efficient components. Our research aim is that through a combination of these techniques we can reduce the challenges facing us in the construction of a large-scale quantum computer, thereby enabling the construction of such a device sooner in time.