Title: Implementation of a scalable universal two-qubit quantum processor with electron and nuclear spins in a trapped ion Show Chinese title

Title: 具有被捕获离子中电子自旋和核自旋的可扩展通用两量子比特量子处理器的实现

Abstract: Increasing the quantum information processing power with limited number of hosts is vital for achieving quantum advantage. Here we propose a novel scheme that achieves a scalable n-ion-2n-qubit quantum processor utilizing four internal levels of each ion, and experimentally implement a 1-ion-2-qubit universal processor using the valence electron spin and nuclear spin of a single 171Yb+ ion. Fidelities of single-qubit and two-qubit gates are around 0.98 obtained by quantum process tomography. Additionally, the Grover's algorithm is implemented with a successful rate exceeding 0.99. We provide explicit scaling-up protocols based on standard laser-less and laser-based frameworks, and further demonstrate that the electron/nuclear-spin scheme allows less demanding two-qubit entangling gates between different ions. The replacement of some inter-atomic gates by intra-atomic gates could increase the fidelity of some quantum circuits. Our work paves the way towards achieving 2n-times increase in the size of quantum computational Hilbert space with n ions. Show Chinese abstract

Abstract: 增加有限数量的宿主量子信息处理能力对于实现量子优势至关重要。 这里我们提出一种新方案，利用每个离子的四个内部能级，实现可扩展的n离子-2n量子比特量子处理器，并实验实现了使用单个171Yb+离子的价电子自旋和核自旋的1离子-2量子比特通用处理器。 通过量子过程层析成像获得的单量子比特和双量子比特门保真度约为0.98。 此外，Grover算法的实现成功率超过0.99。 我们提供了基于标准无激光和有激光框架的明确扩展协议，并进一步证明电子/核自旋方案允许在不同离子之间实现要求更低的双量子比特纠缠门。 将一些原子间门替换为原子内门可以提高某些量子电路的保真度。 我们的工作为实现n离子情况下量子计算希尔伯特空间大小2n倍的增长铺平了道路。