Quantum simulation with superconducting qubit arrays.

超导电路已经成为建造通用量子计算机的有力候选者，但在这个梦想最终实现之前，仍有一系列困难的挑战有待解决。除了商业上的相关应用，用于量子计算的相同电路也可以用于实现多体量子物理的精确模拟。这一科学应用对电路中控制操作的保真度提出了不那么严格的标准，因此很可能实现为最早的真实世界应用之一。该项目将建立在我们小组基于同轴电路元件和离面控制的量子计算新体系结构的最新开发基础上。我们已经演示了两个量子比特级的体系结构，包括接近最先进水平的完整两个量子比特量子逻辑(一个和两个量子比特门的保真度分别为99.9%和98%)[1]。最近尚未发表的工作表明，使用一项新的创新，我们可以在4量子比特电路中达到世界纪录的一致性和保真度，这将使我们能够扩展到大型的2D量子比特阵列[2]。该项目最初将涉及多量子比特电路的设计、模拟、制造和测量，这些电路旨在实现凝聚态物理中感兴趣的哈密顿量，例如玻色和费米-哈伯德模型，特别是为了将电路放大到2D(以及潜在的更远的)。然后，该项目将继续演示16+量子比特的中等规模的量子模拟，其中2D效应变得明显，从而能够观察到这些哈密顿中发生在整体和晶格边缘的现象。EPSRC优先领域：21世纪的产品：量子技术：量子计算机。本项目旨在展示量子计算机的一个重要科学应用--量子物理模拟的实现，它将发展成为物理学研究的一个有价值的新工具。[1]Patterson等人，PR Application12,064013(2019年)[2]Spring等人，PR Application14,024061(2020年)

Superconducting circuits have emerged as a strong candidate for building working universal quantum computers, but a range of difficult challenges still remain to be solved before this dream is finally realized. Besides commercially relevant applications, the same circuits used for quantum computing can also be employed to implement accurate simulations of many-body quantum physics. This scientific application places less stringent criteria on the fidelity of control operations in the circuits, and hence is likely to be realized as one of the earliest real-world applications.This project will build on the recent development of a new architecture for quantum computing in our group based on coaxial circuit elements and out-of-plane control. We have demonstrated the architecture at the two-qubit level, including full two-qubit quantum logic at close to state-of-the-art (99.9% and 98% fidelities for one and two-qubit gate fidelities respectively) [1]. Recent as-yet unpublished work shows that we can reach world record coherence and fidelities in 4-qubit circuits using a new innovation that will enable us to scale to large 2D arrays of qubits [2].The project will initially involve design, simulation, fabrication and measurement of multi-qubit circuits designed to implement Hamiltonians of interest in condensed matter physics, such as the Bose- and Fermi-Hubbard models, in particular with a view to scaling up the circuits to 2D (and potentially further). The project will then move on to demonstrate quantum simulations at an intermediate scale of 16+ qubits, where 2D effects become apparent, enabling observation of phenomena that occur in the bulk and at the edges of lattices in these Hamiltonians.EPSRC Priority area: 21st century products: Quantum technologies: Quantum computers. This project focuses on demonstrating an important scientific application of quantum computers, the implementation of quantum physics simulation, which will develop into a valuable new tool for Physics research.[1] Patterson et al., PR Applied 12, 064013 (2019)[2] Spring et al., PR Applied 14, 024061 (2020)