Fast universal quantum gate above the fault-tolerance threshold in silicon
Fast universal quantum gate above the fault-tolerance threshold in silicon
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DOI：
10.1038/s41586-021-04182-y
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发表时间：
2022-01-20
期刊：
影响因子：
64.8
通讯作者：
Tarucha, Seigo
中科院分区：
文献类型：
--
作者：
Noiri, Akito;Takeda, Kenta;Tarucha, Seigo
能够解决难题的容错量子计算机依赖于量子纠错（1）。最有前途的纠错码之一是表面码（2），它要求通用门的纠错阈值超过99%（3）。在众多的量子位平台中，只有超导电路（4）、捕获离子（5）和金刚石中的氮空位中心（6）满足了这一要求。硅中的电子自旋量子位（7-15）由于其纳米制造能力而特别有希望用于大规模量子计算机，但由于操作缓慢，双量子位门保真度已被限制在98%。在这里，我们展示了一个两个量子比特门保真度为99.5%，沿着与99.8%的单量子比特门保真度，在硅自旋量子比特的快速电气控制使用微磁感应梯度场和可调的两个量子比特耦合。我们确定了量子比特的旋转速度和耦合强度，我们鲁棒地实现高保真门。我们实现了Deutsch-Jozsa和Grover搜索算法，使用我们的通用门集具有很高的成功率。我们的研究结果表明，通用门保真度超过容错阈值，并可能使可扩展的硅量子计算机。
Fault-tolerant quantum computers that can solve hard problems rely on quantum error correction(1). One of the most promising error correction codes is the surface code(2), which requires universal gate fidelities exceeding an error correction threshold of 99 per cent(3). Among the many qubit platforms, only superconducting circuits(4), trapped ions(5) and nitrogen-vacancy centres in diamond(6) have delivered this requirement. Electron spin qubits in silicon(7-15) are particularly promising for a large-scale quantum computer owing to their nanofabrication capability, but the two-qubit gate fidelity has been limited to 98 per cent owing to the slow operation(16). Here we demonstrate a two-qubit gate fidelity of 99.5 per cent, along with single-qubit gate fidelities of 99.8 per cent, in silicon spin qubits by fast electrical control using a micromagnet-induced gradient field and a tunable two-qubit coupling. We identify the qubit rotation speed and coupling strength where we robustly achieve high-fidelity gates. We realize Deutsch-Jozsa and Grover search algorithms with high success rates using our universal gate set. Our results demonstrate universal gate fidelity beyond the fault-tolerance threshold and may enable scalable silicon quantum computers.