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arXiv 0806.2176cond-mat.mes-hall
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Aharonov-Bohm环中量子点的Josephson电流输运

Josephson current transport through a Quantum Dot in an Aharonov-Bohm Ring

Shu-guang Cheng, Yanxia Xing, X. C. Xie, Qing-feng Sun

摘要:

研究了一个量子点位于一个臂上,磁通量$Φ$穿过量子点环的Aharonov-Bohm(AB)干涉仪中的约瑟夫森电流.当磁通量存在时,约瑟夫森电流与超导相的关系变得复杂,通过调节磁通量或量子点的能级$\varepsilon_d$,可以将系统调节到$π$结。由于电子-空穴对称性,约瑟夫森电流$I$具有特性$I(\varepsilon_d,Φ)=I(-\varepsilon_d,Φ+π)$。当一对Andreev束缚态与费米能级对齐时,约瑟夫森电流呈现跳跃。给出了电流跳变的条件。特别地,我们发现电流跳跃的位置和临界电流$I_c$的最大值的位置是相同的。由于两条路径之间的干涉,临界电流PDMATHAMR与量子点能级$\varepsilon_d$的关系呈现出典型的Fano形状,这与相应的正常器件中的Fano效应相似。但它们也表现出一些差异。例如,对于任何参数,临界电流都不会达到零,而正常器件中的电流可以在破坏点达到零。

英文摘要:

The Josephson current through an Aharonov-Bohm (AB) interferometer, in which a quantum dot (QD) is situated on one arm and a magnetic flux $Φ$ threads through the ring, has been investigated. With the existence of the magnetic flux, the relation of the Josephson current and the superconductor phase is complex, and the system can be adjusted to $π$ junction by either modulating the magnetic flux or the QD's energy level $\varepsilon_d$. Due to the electron-hole symmetry, the Josephson current $I$ has the property $I(\varepsilon_d,Φ)=I(-\varepsilon_d,Φ+π)$. The Josephson current exhibits a jump when a pair of Andreev bound states aligns with the Fermi energy. The condition for the current jump is given. In particularly, we find that the position of the current jump and the position of the maximum value of the critical current $I_c$ are identical. Due to the interference between the two paths, the critical current $I_c$ versus the QD's level $\varepsilon_d$ shows a typical Fano shape, which is similar to the Fano effect in the corresponding normal device. But they also show some differences. For example, the critical current never reaches zero for any parameters, while the current in the normal device can reach zero at the destruction point.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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