Scalable Quantum Computing

量子计算旨在以比经典计算机更快的速度解决一些经典（即非量子）问题。从技术上讲，这种加速意味着量子计算机的计算时间比传统计算机更好。三个例子有助于解释。然而，在N个项目的非结构化搜索中找到一个标记项目的时间在N中是线性的，量子搜索可以证明是二次更好的，即只需要N次求值的平方根。量子分解是基于在量子计算机上有效地发现隐藏的周期性，它比次指数时间的经典数场筛法快得多，在线性方程求解中具有潜在的应用前景。量子退火者渴望在一些困难的优化问题上证明比经典计算的加速，量子优势是一个悬而未决的问题。优化问题无处不在，例如在金融和蛋白质折叠中，因此量子退火的成功可能对社会产生巨大的积极影响。

Quantum computing aims to solve some classical (i.e., non-quantum) problems faster than classical computers allow. Technically, this speedup means that the computational time scales better for a quantum computer than for a classical computer. Three examples help to explain. Whereas the time to find a marked item in an unstructured search of N items is linear in N classically, a quantum search is provably quadratically better, i.e., requiring only the square root of N evaluations. Quantum factorization, which is based on finding hidden periodicity efficiently on a quantum computer, is superpolynomially faster than the sub-exponential-time classical number-field sieve and has potential applications to linear-equation solvers. Quantum annealers aspire to demonstrate speedup over classical computing for some hard optimization problems and the quantum advantage is an open question. Optimization problems are ubiquitous, such as in finance and protein folding, so success with quantum annealing could have enormous positive ramifications for society. A key point of these goals is that the quantum computer itself must scale well to larger numbers of qubits and run-times or the theoretical advantage of quantum computing is lost to hardware problems. This research program addresses and seeks to resolve the problems of scalability, driven by the principle of co-design, namely that the type of problem being solved influences choices about architecture and design and the limitations of the computer influences which computational problems are suitable for quantum computing. This research involves one undergraduate student annually, five graduate students and one postdoctoral researcher in strategically important research topics that underpin positively disrupting, i.e., rapidly transforming, computer technology with ramifications in many areas of science, technology and beyond. These trainees will have opportunities to work with experts in experimental physics and in computer science, which prepares them for academic and industrial opportunities in quantum computing. This project aims to advance scalability of quantum computing along the following avenues, namely designing high-fidelity quantum circuits, developing quantum algorithms for dozens-of-qubits quantum computing, creating algorithms for sampling problems inspired by the BosonSampling problem, articulating verification-and-validation to know that components and devices meet standards and do what they are supposed to, and establishing confidentiality, integrity and availability for interconnected quantum things. In this last case, things refers to components, devices and systems and pertains to quantum networking, multi-party quantum communication and quantum computing on the cloud. One graduate student will work on each of these five avenues and a postdoctoral researcher will have the grand view and interconnect these discoveries. The undergraduate students will focus on solving technical issues.