Zhang Xin, Morozova Elizaveta, Rimbach-Russ Maximilian, Jirovec Daniel, Hsiao Tzu-Kan, Fariña Pablo Cova, Wang Chien-An, Oosterhout Stefan D, Sammak Amir, Scappucci Giordano, Veldhorst Menno, Vandersypen Lieven M K
QuTech, Delft University of Technology, Delft, Netherlands.
Kavli Institute of Nanoscience, Delft University of Technology, Delft, Netherlands.
Nat Nanotechnol. 2025 Feb;20(2):209-215. doi: 10.1038/s41565-024-01817-9. Epub 2024 Oct 31.
The coherent control of interacting spins in semiconductor quantum dots is of strong interest for quantum information processing and for studying quantum magnetism from the bottom up. Here we present a 2 × 4 germanium quantum dot array with full and controllable interactions between nearest-neighbour spins. As a demonstration of the level of control, we define four singlet-triplet qubits in this system and show two-axis single-qubit control of each qubit and SWAP-style two-qubit gates between all neighbouring qubit pairs, yielding average single-qubit gate fidelities of 99.49(8)-99.84(1)% and Bell state fidelities of 73(1)-90(1)%. Combining these operations, we experimentally implement a circuit designed to generate and distribute entanglement across the array. A remote Bell state with a fidelity of 75(2)% and concurrence of 22(4)% is achieved. These results highlight the potential of singlet-triplet qubits as a competing platform for quantum computing and indicate that scaling up the control of quantum dot spins in extended bilinear arrays can be feasible.
半导体量子点中相互作用自旋的相干控制对于量子信息处理以及从微观层面研究量子磁性具有重要意义。在此，我们展示了一个2×4锗量子点阵列，其中最近邻自旋之间存在完全且可控的相互作用。作为控制水平的一个例证，我们在该系统中定义了四个单重态 - 三重态量子比特，并展示了每个量子比特的两轴单比特控制以及所有相邻量子比特对之间的SWAP型两比特门，单比特门平均保真度达到99.49(8)-99.84(1)%，贝尔态保真度为73(1)-90(1)%。通过组合这些操作，我们通过实验实现了一个旨在在阵列中生成和分布纠缠的电路。实现了一个保真度为75(2)%且并发度为22(4)%的远程贝尔态。这些结果突出了单重态 - 三重态量子比特作为量子计算竞争平台的潜力，并表明在扩展的双线性阵列中扩大对量子点自旋的控制是可行的。
