Hou Y-H, Yi Y-J, Wu Y-K, Chen Y-Y, Zhang L, Wang Y, Xu Y-L, Zhang C, Mei Q-X, Yang H-X, Ma J-Y, Guo S-A, Ye J, Qi B-X, Zhou Z-C, Hou P-Y, Duan L-M
Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing, PR China.
Hefei National Laboratory, Hefei, PR China.
Nat Commun. 2024 Nov 9;15(1):9710. doi: 10.1038/s41467-024-53405-z.
Two-dimensional (2D) ion crystals may represent a promising path to scale up qubit numbers for ion trap quantum information processing. However, to realize universal quantum computing in this system, individually addressed high-fidelity two-qubit entangling gates still remain challenging due to the inevitable micromotion of ions in a 2D crystal as well as the technical difficulty in 2D addressing. Here we demonstrate two-qubit entangling gates between any ion pairs in a 2D crystal of four ions. We use symmetrically placed crossed acousto-optic deflectors (AODs) to drive Raman transitions and achieve an addressing crosstalk error below 0.1%. We design and demonstrate a gate sequence by alternatingly addressing two target ions, making it compatible with any single-ion addressing techniques without crosstalk from multiple addressing beams. We further examine the gate performance versus the micromotion amplitude of the ions and show that its effect can be compensated by a recalibration of the laser intensity without degrading the gate fidelity. Our work paves the way for ion trap quantum computing with hundreds to thousands of qubits on a 2D ion crystal.
二维（2D）离子晶体可能是扩大离子阱量子信息处理中量子比特数量的一条有前景的途径。然而，要在该系统中实现通用量子计算，由于二维晶体中离子不可避免的微运动以及二维寻址的技术难度，单独寻址的高保真两比特纠缠门仍然具有挑战性。在此，我们展示了在由四个离子组成的二维晶体中任意离子对之间的两比特纠缠门。我们使用对称放置的交叉声光偏转器（AOD）来驱动拉曼跃迁，并实现低于0.1%的寻址串扰误差。我们通过交替寻址两个目标离子来设计并展示一种门序列，使其与任何单离子寻址技术兼容，且不存在来自多个寻址光束的串扰。我们进一步研究了门性能与离子微运动幅度的关系，并表明通过重新校准激光强度可以补偿其影响，而不会降低门保真度。我们的工作为在二维离子晶体上实现具有数百到数千个量子比特的离子阱量子计算铺平了道路。
