Shot noise refers to the autocorrelation of current related to the quantum statistics of discrete electrons. The study of shot noise can provide a deep understanding of the quantum fluctuation of current, owing to the interference between incident and reflected electrons. Electrons experience scattering when in the mesoscopic quantum point contact with materials of intermediate lengths. Thus, electron transport is typically incoherent and quantum channels are reformed in leads through adiabatic constriction. The starting point of the shot noise theory is based on a field operator constructed from incoherent wave functions in leads. However, electron transport is coherent in single-molecule junctions with length scales smaller than the dephasing length. In investigations regarding shot noise in systems with coherent electron transport, using a field operator constructed from coherent wave functions is natural. In this study, we investigated shot noise in a 1,4-benzenedithiol single-molecule junction on the basis of coherent wave functions obtained self-consistently from first-principles approaches. The theoretical value of shot noise in our calculations is S ≈ 4.03 × 10^–26 A²/Hz at V_Bias = 0.01 V. This value is in good agreement with that obtained from a recent experimental measurement (S ≈ 4.37 × 10^–26 A²/Hz).

中文翻译：

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1,4-苯二硫醇单分子结中电流的量子噪声：第一性原理计算

散粒噪声是指与离散电子的量子统计有关的电流的自相关。由于入射和反射电子之间的干扰，散粒噪声的研究可以提供对电流量子波动的深刻理解。当电子在介观量子点与中等长度的材料接触时，电子会经历散射。因此，电子传输通常是不相干的，并且通过绝热收缩在引线中重新形成了量子通道。散粒噪声理论的起点是基于由导线中非相干波函数构造的场算子。但是，电子传输在单分子结中是连贯的，其长度尺度小于移相长度。在有关具有相干电子传输的系统中散粒噪声的研究中，使用由相干波函数构造的场算子是很自然的。在这项研究中，我们根据从第一原理方法自洽获得的相干波函数，研究了1,4-苯二硫醇单分子结中的散粒噪声。在我们的计算中散粒噪声的理论值为小号≈4.03×10 ^-26阿² / Hz的在V_偏压= 0.01V。该值是在与从最近的实验测量（获得良好的协议小号≈4.37×10 ^-26阿² /赫兹）。