Ghost Fano resonance in a double quantum dot molecule attached to leads

Guevara, M. L. Ladrón de; Claro, F.; Orellana, P. A.

doi:10.1103/physrevb.67.195335

Cited by 307 publications

(162 citation statements)

References 30 publications

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“…The asymmetric peak, which may be regarded as a Fanolike structure, is caused by the interference between two conduction channels having two distinct Kondo resonances. This type of interference plays a crucial role to determine the Kondo-assisted conductance in DQD systems [15,19,20,21,34,51]. With the increase of x, the maximum of the asymmetric resonance of T (ε) in Fig.…”

Section: Non-polarized Leadsmentioning

confidence: 99%

“…4(a). As x increases, one of the resonances (lower-energy side), which is composed of the "bonding" Kondo state of the DQD, becomes sharp around the Fermi energy, while the other "anti-bonding" Kondo state (higher-energy side) is broadened above the Fermi level [15,19,20,21,34,51]. This tendency results from the fact that the bonding state is almost decoupled from the leads while the anti-bonding state is still tightly connected to the leads as x → 1.…”

Section: Non-polarized Leadsmentioning

confidence: 99%

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Interference effects on Kondo-assisted transport through double quantum dots

2005

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We systematically investigate electron transport through double quantum dots with particular emphasis on interference induced via multiple paths of electron propagation. By means of the slave-boson mean-field approximation, we calculate the conductance, the local density of states, the transmission probability in the Kondo regime at zero temperature. It is clarified how the Kondoassisted transport changes its properties when the system is continuously changed among the serial, parallel and T-shaped double dots. The obtained results for the conductance are explained in terms of the Kondo resonances influenced by interference effects. We also discuss the impacts due to the spin-polarization of ferromagnetic leads.

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Section: Non-polarized Leadsmentioning

confidence: 99%

Section: Non-polarized Leadsmentioning

confidence: 99%

Interference effects on Kondo-assisted transport through double quantum dots

2005

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“…One of the simplest systems where the interference effects are clearly visible, consists of two QDs connected in parallel to electron reservoirs (metallic or semiconducting leads). This interferometer-like geometry allows observation of such quantum phenomena like the Aharonov-Bohm oscillations and the Fano antiresonance 1,2,3,4,5,6,7,8,9,10,11,12,13 . Conductance of systems consisting of three or more QDs reveals further interesting features of quantum transport 14,15,16,17,18,19,20,21,22,23,24 .…”

Section: Introductionmentioning

confidence: 99%

Dicke-like effect in spin-polarized transport through coupled quantum dots

Trocha

Barnaś

2008

J. Phys.: Condens. Matter

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Spin-dependent electronic transport through a quantum dot side-coupled to two quantum dots and attached to ferromagnetic leads with collinear (parallel and antiparallel) magnetizations is analyzed theoretically. The intra-dot Coulomb correlations are taken into account, whereas the inter-dot ones are neglected. Transport characteristics, i.e. conductance and tunnel magnetoresistance associated with the magnetization rotation from parallel to antiparallel configurations, are calculated by the noneqiulibrium Green function technique. The Green functions are derived by the equation of motion method in the Hartree-Fock approximation. The conductance spectra are shown to reveal features similar to the Dicke resonance in atomic physics.

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“…A similar coupling configuration of the DQD model has been studied in the noninteracting case. [22] Since the ISS interaction can be written in an SU(2) singlet form [23] …”

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confidence: 99%

Swapping Kondo resonances in coupled double quantum dots

et al. 2005

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Strong electron and spin correlations are studied in parallel-coupled double quantum dots with interdot spin superexchange J. In the Kondo regime with degenerate dot energy levels, a coherent transport occurs at zero temperature, where two entangled (bonding and antibonding) resonances are formed near the Fermi energy. When increasing J or the dot-lead parallel-coupling asymmetry ratio Γ2/Γ1, a swap between two entangled resonances occurs and the line shapes of the linear conductance are interchanged. The zero-bias differential conductance shows a peak at the critical values. Such a peculiar effect with the virtue of many-body coherence may be useful in future quantum computing.A large number of proposals have been made to materialize quantum bits (qubits) and quantum computing. Among these proposals, coupled quantum dot (QD) systems are particularly attractive.[1] The spin degree of freedom of the localized electrons on the dots is considered as a qubit due to the comparatively long coherence time. A key challenge is the construction of coupled double QD (DQD) to perform a swap operation, i.e. exchanging the electron spin states on the two dots. When the square root of a swap operation is combined with other isolated qubit rotations, a quantum controlled-NOT gate can be built and any quantum algorithms can be implemented.[2] In the coupled DQD, two local electrons form a singlet state. It has been proposed that the swap operation can be realized by tuning the time-dependent interdot spin superexchange (ISS) J(t) from positive to negative, flopping the singlet and triplet states. [1,3] In this Letter, we propose a simple and reliable mechanism to perform such a swap process in a parallel-coupled DQD at low temperatures. It has been well-established that under the Coulomb blockade with odd number electrons on a single QD, a quantum coherent many-body (Kondo) resonance is formed near the Fermi energy in the dot density of states (DOS) [4]. The Kondo effect for even number electrons on a single multilevel dot and possible phase transitions between singlet and triplet states have been considered for both "vertical" [5] and "lateral" [6,7,8,9] configurations. For the coupled DQD with degenerate energy levels, the Kondo behavior and the ISS interplay and strongly compete, as seen in the bulk two-impurity Kondo problem,[10] and a question arises whether there exists a spin entangled state composed of the coherent Kondo resonances.[11] Previous experimental and theoretical studies have mainly focused on the serial-coupled DQD [12,13,14,15,16,17,18,19], except for Ref. 9, 19. However, it has been recently realized that the serial geometry is unsuitable for studying this competition experimentally and a direct evidence for observing spin entanglement between the dot local electrons could be sought in the parallel coupled configuration. [20] It has thus motivated us to investigate whether and how this competition manifests itself in the coherent transport through DQD in the parallel configuration.For a degenerate DQD with ...

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Ghost Fano resonance in a double quantum dot molecule attached to leads

Cited by 307 publications

References 30 publications

Interference effects on Kondo-assisted transport through double quantum dots

Interference effects on Kondo-assisted transport through double quantum dots

Dicke-like effect in spin-polarized transport through coupled quantum dots

Swapping Kondo resonances in coupled double quantum dots

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