Fano resonance and persistent current of a quantum ring

Eric R. Hedin, Сатанин Аркадий Михайлович, Yong Suk Joe

Sigríður Sif Gylfadóttir

T. Bland, IV Yatsuta, M Edwards +4 more

Luo Guo-zhong

In this paper,we studied the problem of persistent current and transmission of two contacted Aharonov-Bohm Rings coupled to extent leads,and give the analytical solution.The conditions of observing persistent current,zero and perfect transmission are discussed,and the Fano resonance is studied.

Guang-Yu Yi, Zhichao Li, Xiaohui Chen +2 more

The Josephson effect in a superconductor/triple-quantum-dot ring/superconductor structure is theoretically investigated. We find that in this structure, interdot spin correlation can be driven, which contributes to the occurrence of new 0 and $\ensuremath{\pi}$ phases of the Josephson current. Moreover, in the 0-$\ensuremath{\pi}$ phase-transition process, an intermediate bistable phase appears in which the Josephson current is completely suppressed. By analyzing the interdot spin correlation, the electron motion mechanism is clarified. We then attribute the disappearance of the Josephson current to the occurrence of the Josephson-Fano effect. What is interesting is that the disappearing Josephson current is accompanied by the apparent persistent current in the ring whose direction is determined by the superconducting phase difference. With the calculated results, we consider such a structure to be a candidate for the realization of the persistent current bit.

Kai Ma, Yundong Zhang, Huaiyin Su +3 more

In this paper, we realize tunable Fano and electromagnetically induced transparency (EIT)-like resonances in the outputs of a nested feedback ring resonator. Compared with the traditional add-drop ring resonator, the feedback arm introduces interference between different resonance modes. Using coupled mode theory, we reveal that the output Fano resonances are the interference of discrete modes and continuum modes, whereas the EIT-like resonance only appears in the over-coupled state. We experimentally confirm the two effects using optical fiber ring resonators, finding that the Fano effect can be easily controlled with phase shifts in the feedback arm. Moreover, we achieve the double Fano resonance, which displays an ‘X’ type lineshape utilizing one ring resonator, predicting it to be a good candidate in wavelength monitor. The proposed simple configuration provides a platform to study Fano and EIT-like effect, which is useful in the optical filter, fast and slow light, optical switching, and optical sensing.