Kondo Resonance versus Fano Interference in Double Quantum Dots Coupled to a Two-Lead One-Ring System

We analyse the transport properties of a coupled double quantum dot （DQD） device with one of the dots （QD1） coupled to metallic leads and the other （QD2） embedded in an Aharonov-Bhom （A-B） ring by means of the slaveboson mean-field theory. It is found that in this system, the Kondo resonance and the Fano interference exist simultaneously, the enhancing Kondo effect and the increasing hopping of the QD2-Ring destroy the localized electron state in the QD2 for the QD1-leads, and accordingly, the Fano interference between the DQD-leads and the QD1-leads are suppressed. Under some conditions, the Fano interference can be quenched fully and the single Kondo resonance of the QD1-leads comes into being. Moreover, when the magnetic flux of the A-B ring is zero, the influence of the parity of the A-B ring on the transport properties is very weak, but this influence becomes more obvious with non-zero magnetic flux. Thus this model may be a candidate for future device applications.     

T型耦合双量子点系统的非对等Kondo共振分裂传输

利用隶玻色子平均场近似理论,并借助于单杂质的Anderson模型的哈密顿量,研究了T型耦合双量子点嵌入正常电极的基态输运性质.结果表明：在体系处于平衡状态时,随着双量子点的耦合强度增加,体系的Kondo 效应被削弱. 当耦合强度足够强时,Kondo量子点态密度的Kondo共振单峰分裂成两个不对等的Kondo共振双峰.在体系处于非平衡状态时,增加两电极的偏压,态密度的Kondo分裂的非对等性明显加强. 关键词： Kondo效应 态密度 格林函数法 耦合双量子点     

Fano Interference versus Kondo Effect in Strongly Correlated T-Shaped Quantum Dots Embedded in an Aharonov-Bohm Ring

We theoretically investigate the properties of the ground state of the strongly correlated T-shaped double quantum dots embedded in an Aharonov-Bohm ring in the Kondo regime by means of the one-impurity Anderson Hamiltonian. It is found that in this system, the persistent current depends sensitively on the parity and size of the ring. With the increase of interdot coupling, the persistent current is suppressed due to the enhancing Fano interference weakening the Kondo effect. Moreover, when the spin of quantum dot embedded in the Aharonov- Bohm ring is screened, the persistent current peak is not affected by interdot coupling. Thus this model may be a new candidate for detecting Kondo screening cloud.     

嵌入T型耦合双量子点介观A-B环系统的显著Fano 效应

利用平均场近似理论,研究了一个嵌入T型弱耦合双量子点的介观环系统的基态性质. 结果表明,体系中复杂的基态性质源于Kondo效应与Fano效应相互竞争. 当介观环的尺寸达到足以产生完全Kondo共振时,随双量子点间耦合强度的增强,尖锐的持续电流峰出现了,且越发显著,这说明体系中存在着显著的Fano 效应. 但介观环的Kondo共振持续电流峰值却几乎不发生变化,这为测定Kondo 屏蔽云提供了一个新的可能模型. 关键词： 耦合量子点 持续电流 Kondo效应 Fano 效应