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arXiv 0811.3461cond-mat.mes-hall
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具有点间排斥的双量子点的输运

Transport through a double quantum dot with interdot repulsion

Yunori Nisikawa, Akira Oguri

摘要:

利用数值重整化群(NRG)方法研究了具有点间跳跃$t$、点内排斥$U$和点间排斥$U^{\prime}$的双量子点的输运.在半填充状态下,通过两个相移计算了双量子点连接到两个具有杂化强度$Γ$的非相互作用引线上的准粒子的二端串联和四端并联结构的电导.对于小的$t/Γ$和$U^{\prime}/U$值,在两端串联配置的电导被抑制到几乎为零。在此区域,四端并联结构的电导出现平台,几乎达到两种导电模式的统一极限值$4e^{2}/h$。对于较大的$t/Γ$或$U^{\prime}/U$值,两个电导都被抑制到几乎为零。在双量子点中,只有在电子组态的交叉区附近,二端串联组态的电导才几乎达到幺正极限值$2e^{2}/h$。通过局域电荷的行为和一些热力学量,讨论了输运与电子组态的关系。

英文摘要:

We study transport through a double quantum dot with interdot hopping $t$, intradot repulsion $U$ and interdot repulsion $U^{\prime}$, using the numerical renormalization group (NRG) method. At half-filling, the conductances in two-terminal series and four-terminal parallel configuration are calculated via two phase shifts for quasi-particles of double quantum dot connected to two noninteracting leads with hybridization strength $Γ$. For small values of $t/Γ$ and $U^{\prime}/U$, conductance in the two-terminal series configuration is suppressed to almost zero. In this region, plateau of conductance in the four-terminal parallel configuration appears and almost reaches a unitary limit value $4e^{2}/h$ of two conducting modes. For large values of $t/Γ$ or $U^{\prime}/U$, both conductances are suppressed to almost zero. The conductance in the two-terminal series configuration almost reaches a unitary limit value $2e^{2}/h$ only around cross-over regions of electron-configuration in double quantum dot. Through the behavior of the local charge and some thermodynamic quantities, we discuss the relation between transport and electron-configuration.

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