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arXiv 0706.2240cond-mat.mes-hall
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分子量子点中振动介导的共振隧穿和散粒噪声

Vibration-mediated resonant tunneling and shot noise through a molecular quantum dot

X. Y. Shen, Bing Dong, X. L. Lei, N. J. M. Horing

摘要:

受最近的一个实验的启发,在悬浮的碳纳米管连接到两个正常电极的非线性隧穿[S。Sapmaz,{ \it等人},物理修订版信函{ \bf 96},26801(2006)],我们研究了通过具有两个电子轨道的分子量子点的非平衡振动介导的顺序隧穿,所述两个电子轨道不对称地耦合到两个电极并且与内部振动模式强烈相互作用,所述内部振动模式本身弱耦合到耗散声子浴。为了这个目的,我们建立速率方程使用通用的量子朗之万方程的方法。基于这些方程,我们详细研究了电流-电压特性和零频率散粒噪声,特别注意了由电子-声子耦合诱导的{ \em选择性单电子单向级联}引起的负微分电导和超泊松电流噪声的出现的提前或推迟。

英文摘要:

Motivated by a recent experiment on nonlinear tunneling in a suspended Carbon nanotube connected to two normal electrodes [S. Sapmaz, {\it et al}., Phys. Rev. Lett. {\bf 96}, 26801 (2006)], we investigate nonequilibrium vibration-mediated sequential tunneling through a molecular quantum dot with two electronic orbitals asymmetrically coupled to two electrodes and strongly interacting with an internal vibrational mode, which is itself weakly coupled to a dissipative phonon bath. For this purpose, we establish rate equations using a generic quantum Langevin equation approach. Based on these equations, we study in detail the current-voltage characteristics and zero-frequency shot noise, paying special attention to the advanced or postponed of the appearance of negative differential conductance and super-Poissonian current noise resulting from electron-phonon-coupling induced {\em selective unidirectional cascades of single-electron transitions}.

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