Narrowing of the Overhauser field distribution by feedback-enhanced dynamic nuclear polarization
Narrowing of the Overhauser field distribution by feedback-enhanced dynamic nuclear polarization
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DOI：
10.1103/physrevb.92.195428
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发表时间：
2015-03
影响因子：
3.7
通讯作者：
S. Tenberg;R. McNeil;S. Rubbert;H. Bluhm
中科院分区：
文献类型：
--
作者：
S. Tenberg;R. McNeil;S. Rubbert;H. Bluhm
在许多电子自旋量子比特系统中，相干控制受到主体材料的波动核自旋浴的损害。以前的实验表明，动态核极化反馈，显着延长非均匀退相时间T_2 ^*$，缩小分布的核欧弗豪泽场波动。我们提出了一个模型，可实现的缩小的Overhauser场的泵浦速率和噪声幅度，并找到合理的协议与实验数据。结果表明，以往的量子点实验受到泵浦机制泵浦速率的限制。在这里，我们提出了一个替代的反馈方案，使用电子偶极自旋共振。顺序地施加两个交流电场，其频率与所需的拉莫尔频率稍微失谐，导致具有稳定固定点的泵浦曲线。我们的模型预测，可以实现微秒量级的T_2 ^*$值。
In many electron spin qubit systems coherent control is impaired by the fluctuating nuclear spin bath of the host material. Previous experiments have shown dynamic nuclear polarization with feedback to significantly prolong the inhomogeneous dephasing time $T_2^*$ by narrowing the distribution of nuclear Overhauser field fluctuations. We present a model relating the achievable narrowing of the Overhauser field to both the pump rate and the noise magnitude and find reasonable agreement with experimental data. It shows that former experiments on gated GaAs quantum dots were limited by the pump rate of the pumping mechanism used. Here we propose an alternative feedback scheme using electron dipole spin resonance. Sequentially applying two ac electric fields with frequencies slightly detuned from the desired Larmor frequency results in a pump curve with a stable fixed point. Our model predicts that $T_2^*$ values on the order of microseconds can be achieved.