Storing quantum information for 30 seconds in a nanoelectronic device
Storing quantum information for 30 seconds in a nanoelectronic device
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DOI：
10.1038/nnano.2014.211
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发表时间：
2014-12-01
影响因子：
38.3
通讯作者：
Morello, Andrea
中科院分区：
文献类型：
--
作者：
Muhonen, Juha T.;Dehollain, Juan P.;Morello, Andrea
半导体(1)中电子或原子核的自旋自然实现了量子信息的单位--量子比特。此外，由于半导体目前被用于电子工业，在半导体中开发量子比特将是实现可扩展量子信息设备的一条很有前途的途径。然而，固态环境可能会在量子比特和周围原子的核自旋之间提供有害的相互作用(3)，或者由氧化物和界面中的缺陷引起的电荷和自旋波动(4)。对于硅这样的材料，自旋为零的Si-28同位素的浓缩大大减少了自旋浴的退相干(5)。对Si-28晶体中的体自旋系综的实验确实证明了超乎寻常的相干时间(6-8)。然而，目前还不清楚这些是否会在单自旋水平上持续存在，也就是在靠近非晶界面门控纳米结构中。在这里，我们介绍了单个P-31电子和核自旋量子比特在顶部选通纳米结构中的相干操作，该结构是在同位素工程的Si-28衬底上制造的。P-31核自旋设定了固态中任何单个量子比特的新基准相干时间(>；30 S，具有Carr-Purcell-Meiom-Gill(CPMG)序列)，并达到>；99.99%的控制保真度。电子自旋CpMG相干时间超过0.5S，详细的噪声谱(9)表明--与普遍认为的相反--它不受界面接近的限制。相反，消相干可能是由设备外部的热和磁噪声主导的，因此可以进一步改进。
The spin of an electron or a nucleus in a semiconductor(1) naturally implements the unit of quantum information-the qubit. In addition, because semiconductors are currently used in the electronics industry, developing qubits in semiconductors would be a promising route to realize scalable quantum information devices(2). The solid-state environment, however, may provide deleterious interactions between the qubit and the nuclear spins of surrounding atoms(3), or charge and spin fluctuations arising from defects in oxides and interfaces(4). For materials such as silicon, enrichment of the spin-zero Si-28 isotope drastically reduces spin-bath decoherence(5). Experiments on bulk spin ensembles in Si-28 crystals have indeed demonstrated extraordinary coherence times(6-8). However, it remained unclear whether these would persist at the single-spin level, in gated nanostructures near amorphous interfaces. Here, we present the coherent operation of individual P-31 electron and nuclear spin qubits in a top-gated nanostructure, fabricated on an isotopically engineered Si-28 substrate. The P-31 nuclear spin sets the new benchmark coherence time (>30 s with Carr-Purcell-Meiboom-Gill (CPMG) sequence) of any single qubit in the solid state and reaches >99.99% control fidelity. The electron spin CPMG coherence time exceeds 0.5 s, and detailed noise spectroscopy(9) indicates that-contrary to widespread belief-it is not limited by the proximity to an interface. Instead, decoherence is probably dominated by thermal and magnetic noise external to the device, and is thus amenable to further improvement.