An addressable quantum dot qubit with fault-tolerant control-fidelity
An addressable quantum dot qubit with fault-tolerant control-fidelity
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DOI：
10.1038/nnano.2014.216
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发表时间：
2014-12-01
影响因子：
38.3
通讯作者：
Dzurak, A. S.
中科院分区：
文献类型：
--
作者：
Veldhorst, M.;Hwang, J. C. C.;Dzurak, A. S.
基于自旋的量子计算（1，2）最近取得了令人兴奋的进展，量子比特是利用金刚石中的氮空位中心和硅中的磷原子实现的（3）。例如，碳（4）和硅（5）的无自旋同位素的存在使长相干时间成为可能。然而，尽管单原子纳米技术前景看好，但在耦合这些量子位并单独寻址它们方面仍然存在重大挑战。相反，光刻定义的量子点具有可以精确设计的交换耦合（1），但与噪声的强耦合严重限制了它们的失相时间和控制精度。在这里，我们联合收割机结合了两种自旋量子比特方案的最佳方面，并在同位素工程硅中展示了一种门可寻址量子点量子比特，其控制保真度为99.6%，通过基于Clifford的随机基准测试获得，并与容错量子计算所需的一致（7，8）。该量子比特具有失相时间T-2（*）= 120 μ s和相干时间T-2 = 28 ms，这两个数量级都比其他类型的半导体量子比特大。通过栅极电压调整电子g* 因子，我们可以使电子自旋共振频率斯塔克移动超过2.4 kHz电子自旋共振线宽的3,000倍，为可寻址高保真量子位的大规模阵列提供了一条直接途径，这些量子位与现有的制造技术兼容。
Exciting progress towards spin-based quantum computing(1,2) has recently been made with qubits realized using nitrogen-vacancy centres in diamond and phosphorus atoms in silicon(3). For example, long coherence times were made possible by the presence of spin-free isotopes of carbon(4) and silicon(5). However, despite promising single-atom nanotechnologies(6), there remain substantial challenges in coupling such qubits and addressing them individually. Conversely, lithographically defined quantum dots have an exchange coupling that can be precisely engineered(1), but strong coupling to noise has severely limited their dephasing times and control fidelities. Here, we combine the best aspects of both spin qubit schemes and demonstrate a gate-addressable quantum dot qubit in isotopically engineered silicon with a control fidelity of 99.6%, obtained via Clifford-based randomized benchmarking and consistent with that required for fault-tolerant quantum computing(7,8). This qubit has dephasing time T-2(*) = 120 mu s and coherence time T-2 = 28 ms, both orders of magnitude larger than in other types of semiconductor qubit. By gate-voltage-tuning the electron g*-factor we can Stark shift the electron spin resonance frequency by more than 3,000 times the 2.4 kHz electron spin resonance linewidth, providing a direct route to large-scale arrays of addressable high-fidelity qubits that are compatible with existing manufacturing technologies.