Quenching of dynamic nuclear polarization by spin-orbit coupling in GaAs quantum dots.
Quenching of dynamic nuclear polarization by spin-orbit coupling in GaAs quantum dots.
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DOI：
10.1038/ncomms8682
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发表时间：
2015-07-17
影响因子：
16.6
通讯作者：
Yacoby A
中科院分区：
文献类型：
--
作者：
Nichol JM;Harvey SP;Shulman MD;Pal A;Umansky V;Rashba EI;Halperin BI;Yacoby A
中心自旋问题是广泛研究的量子退相干模型。当电子角动量转移到核自旋时，动态核极化发生在中心自旋系统中，并在量子信息处理中用于相干自旋操纵。然而，限制这一过程的机制仍然只有部分被了解。在这里，我们证明自旋轨道耦合可以淬灭 GaAs 量子点中的动态核极化，因为尽管 GaAs 中的自旋轨道耦合较弱，但电子核系统中的自旋守恒定律被违反。使用朗道-齐纳扫描来测量电子自旋翻转概率的静态和动态特性，我们观察到自旋轨道和超精细相互作用的大小取决于所施加磁场的大小和方向。我们发现，当自旋轨道贡献超过超精细时，动态核极化就会被淬灭，这与理论模型一致。我们的结果揭示了中心自旋系统中自旋轨道耦合的惊人强烈效应。 动态核极化是电子角动量向核自旋的转移，是相干操纵量子信息中自旋的潜在途径。在这里，作者表明自旋轨道耦合可以淬灭砷化镓量子点中的动态核极化。
The central-spin problem is a widely studied model of quantum decoherence. Dynamic nuclear polarization occurs in central-spin systems when electronic angular momentum is transferred to nuclear spins and is exploited in quantum information processing for coherent spin manipulation. However, the mechanisms limiting this process remain only partially understood. Here we show that spin–orbit coupling can quench dynamic nuclear polarization in a GaAs quantum dot, because spin conservation is violated in the electron–nuclear system, despite weak spin–orbit coupling in GaAs. Using Landau–Zener sweeps to measure static and dynamic properties of the electron spin–flip probability, we observe that the size of the spin–orbit and hyperfine interactions depends on the magnitude and direction of applied magnetic field. We find that dynamic nuclear polarization is quenched when the spin–orbit contribution exceeds the hyperfine, in agreement with a theoretical model. Our results shed light on the surprisingly strong effect of spin–orbit coupling in central-spin systems. Dynamic nuclear polarization is the transfer of electronic angular momentum to nuclear spins and is a potential route for coherently manipulating spin in quantum information. Here, the authors show that spin–orbit coupling can quench dynamic nuclear polarization in a gallium arsenide quantum dot.