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arXiv 1607.08696cond-mat.mes-hall
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单原子电子泵的动力学

Dynamics of a single-atom electron pump

J. van der Heijden, G. C. Tettamanzi, S. Rogge

摘要:

基于孤立杂质原子的单电子泵最近已经在实验上得到证实。在这些装置中,原子的库仑势产生具有大的充电能量和相当大的轨道能级间距的局部电子状态,从而实现稳健的电荷捕获过程。在这些单原子泵中,限制势几乎不受系统周期性驱动的影响。这与经常使用的栅极定义的量子点泵相反,对于栅极定义的量子点泵,强烈的时间依赖性电势导致显著不同的电荷泵浦过程。在这里,我们描述的行为和性能的原子,单参数,电子泵。这是通过考虑一个电子在嵌入硅双栅晶体管的磷原子上的加载、隔离和卸载来完成的。原子泵的最重要的特征是其非常孤立的基态,其可以通过高得多的激发态的快速加载和随后的快速弛豫过程来填充。这导致泵浦精度的显著增加,并且与由于非绝热激发而对量子点泵浦观察到的激发态的不利作用相反。的泵浦性能作为掺杂剂的位置的函数进行了研究,揭示了对预期的原子位置的变化鲁棒的泵浦行为。

英文摘要:

Single-electron pumps based on isolated impurity atoms have recently been experimentally demonstrated. In these devices the Coulomb potential of an atom creates a localised electron state with a large charging energy and considerable orbital level spacings, enabling robust charge capturing processes. In these single-atom pumps, the confinement potential is hardly affected by the periodic driving of the system. This is in contrast to the often used gate-defined quantum dot pumps, for which a strongly time-dependent potential leads to significantly different charge pumping processes. Here we describe the behaviour and the performance of an atomic, single parameter, electron pump. This is done by considering the loading, isolating and unloading of one electron at the time, on a phosphorous atom embedded in a silicon double gate transistor. The most important feature of the atom pump is its very isolated ground state, which can be populated through the fast loading of much higher lying excited states and a subsequent fast relaxation proces. This leads to a substantial increase in pumping accuracy, and is opposed to the adverse role of excited states as observed for quantum dot pumps due to non-adiabatic excitations. The pumping performances are investigated as a function of dopant position, revealing a pumping behaviour robust against the expected variability in atomic position.

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