Precision tomography of a three-qubit donor quantum processor in silicon
Precision tomography of a three-qubit donor quantum processor in silicon
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DOI：
10.1038/s41586-021-04292-7
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发表时间：
2022-01-20
期刊：
影响因子：
64.8
通讯作者：
Morello, Andrea
中科院分区：
文献类型：
--
作者：
Madzik, Mateusz T.;Asaad, Serwan;Morello, Andrea
核自旋是第一个被考虑用于量子信息处理的物理平台之一（1，2），因为它们具有特殊的量子相干性（3）和原子尺度的足迹。然而，它们在量子计算方面的全部潜力尚未实现，这是由于缺乏将可扩展设备内的核量子位与具有足够保真度的多量子位操作相结合以维持容错量子计算的方法。在这里，我们展示了通用的量子逻辑操作使用一对离子注入的P-31施主核在硅纳米电子器件。通过对共享电子自旋（4）赋予几何相位，得到了一个核双量子比特控制Z门，并用于制备纠缠态，量子效率高达94.2（2.7）%。量子操作使用门集层析成像（GST）（5）进行精确表征，产生高达99.95（2）%的单量子位平均门保真度，99.37（11）%的双量子位平均门保真度和98.95（4）%的双量子位制备/测量保真度。这三个指标表明，硅中的核自旋正在接近容错量子处理器所需的性能。然后，我们通过产生具有92.5（1.0%）保真度的Greenberger-Horne-Zeilinger三量子比特态来证明两个核和共享电子之间的纠缠。由于半导体中的电子自旋量子比特可以进一步耦合到其他电子（7-9）或物理穿梭于不同的位置（10，11），这些结果为使用供体核和电子自旋的可扩展量子信息处理建立了可行的路线。
Nuclear spins were among the first physical platforms to be considered for quantum information processing(1,2), because of their exceptional quantum coherence(3) and atomic-scale footprint. However, their full potential for quantum computing has not yet been realized, owing to the lack of methods with which to link nuclear qubits within a scalable device combined with multi-qubit operations with sufficient fidelity to sustain fault-tolerant quantum computation. Here we demonstrate universal quantum logic operations using a pair of ion-implanted P-31 donor nuclei in a silicon nanoelectronic device. A nuclear two-qubit controlled-Z gate is obtained by imparting a geometric phase to a shared electron spin(4), and used to prepare entangled Bell states with fidelities up to 94.2(2.7)%. The quantum operations are precisely characterized using gate set tomography (GST)(5), yielding one-qubit average gate fidelities up to 99.95(2)%, two-qubit average gate fidelity of 99.37(11)% and two-qubit preparation/measurement fidelities of 98.95(4)%. These three metrics indicate that nuclear spins in silicon are approaching the performance demanded in fault-tolerant quantum processors(6). We then demonstrate entanglement between the two nuclei and the shared electron by producing a Greenberger-Horne-Zeilinger three-qubit state with 92.5(1.0)% fidelity. Because electron spin qubits in semiconductors can be further coupled to other electrons(7-9) or physically shuttled across different locations(10,11), these results establish a viable route for scalable quantum information processing using donor nuclear and electron spins.