Nuclear spin quantum register in an optically active semiconductor quantum dot
Nuclear spin quantum register in an optically active semiconductor quantum dot
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DOI：
10.1038/s41565-020-0769-3
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发表时间：
2020-09-28
影响因子：
38.3
通讯作者：
Rastelli, Armando
中科院分区：
文献类型：
--
作者：
Chekhovich, Evgeny A.;da Silva, Saimon F. Covre;Rastelli, Armando
外延量子点电荷自旋量子比特提供了有效的量子光连接，但它们的相干性受到与原子核自旋的纳米尺度集合相互作用的限制。利用核自旋替代其硬件，无应变的GaAs/AlGaAs量子点可以构成全功能的双量子位量子寄存器。外延量子点(QD)长期以来一直被认为是一种很有前途的电荷自旋量子位，为量子光和先进的半导体纳米制造技术提供了有效的接口。然而，电荷自旋相干性受到与原子核自旋的纳米尺度系综相互作用的限制，这在应变自组装点中尤其有问题。在这里，我们使用无应变的GaAs/AlGaAs量子点，展示了一个全功能的两量子位量子寄存器，它使用了纳米尺度的砷四极核自旋系综作为其硬件。定制的射频脉冲允许量子状态存储长达20ms，并用于几微秒的单量子比特和双量子比特控制门，保真度超过97%。将长相干和高保真控制与光学初始化和读出相结合，实现了Grover搜索和Deutsch-Jozsa算法等基准量子计算。我们的结果表明，QD核是一种潜在的量子信息源，可以在未来的QD电路中补充电荷自旋和轻粒子。
Epitaxial quantum dot charge spin qubits offer efficient quantum light links, but their coherence is limited by interactions with the nanoscale ensemble of atomic nuclear spins. Employing nuclear spins instead as its hardware, strain-free GaAs/AlGaAs quantum dots can constitute a fully functional two-qubit quantum register.Epitaxial quantum dots (QDs) have long been identified as promising charge spin qubits offering an efficient interface to quantum light and advanced semiconductor nanofabrication technologies. However, charge spin coherence is limited by interaction with the nanoscale ensemble of atomic nuclear spins, which is particularly problematic in strained self-assembled dots. Here, we use strain-free GaAs/AlGaAs QDs, demonstrating a fully functioning two-qubit quantum register using the nanoscale ensemble of arsenic quadrupolar nuclear spins as its hardware. Tailored radio-frequency pulses allow quantum state storage for up to 20 ms, and are used for few-microsecond single-qubit and two-qubit control gates with fidelities exceeding 97%. Combining long coherence and high-fidelity control with optical initialization and readout, we implement benchmark quantum computations such as Grover's search and the Deutsch-Jozsa algorithm. Our results identify QD nuclei as a potential quantum information resource, which can complement charge spins and light particles in future QD circuits.