Kondo and Dicke effect in quantum dots side coupled to a quantum wire

Orellana, P. A.; Lara, Gustavo A.; Anda, E. V.

doi:10.1103/physrevb.74.193315

Cited by 37 publications

(31 citation statements)

References 22 publications

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“…The MO |− , in the 2LSU2 regime (ν = 1), is an electronic dark state that cannot interact directly with the conduction electrons. Such state has been extensively studied in different systems, namely, as Dicke effect [22][23][24] or bound states in the continuum (BICs), 25,26 which can produce Fano resonances in the conductance. 27 The original Dicke effect in quantum optics 28 takes place through spontaneous emission, by two closely spaced atoms (of the same species), which emit a photon into a common environment.…”

Section: A Model Hamiltonianmentioning

confidence: 99%

Transport in carbon nanotubes: Two-level SU(2) regime reveals subtle competition between Kondo and intermediate valence states

et al. 2011

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In this work, we use three different numerical techniques to study the charge transport properties of a system in the two-level SU(2) (2LSU2) regime, obtained from an SU(4) model Hamiltonian by introducing orbital mixing of the degenerate orbitals via coupling to the leads. SU(4) Kondo physics has been experimentally observed, and studied in detail, in Carbon Nanotube Quantum Dots. Adopting a two molecular orbital basis, the Hamiltonian is recast into a form where one of the molecular orbitals decouples from the charge reservoir, although still interacting capacitively with the other molecular orbital. This basis transformation explains in a clear way how the charge transport in this system turns from double-to single-channel when it transitions from the SU(4) to the 2LSU2 regime. The charge occupancy of these molecular orbitals displays gate-potential-dependent occupancy oscillations that arise from a competition between the Kondo and Intermediate Valence states. The determination of whether the Kondo or the Intermediate Valence state is more favorable, for a specific value of gate potential, is assessed by the definition of an energy scale T0, which is calculated through DMRG. We speculate that the calculation of T0 may provide experimentalists with a useful tool to analyze correlated charge transport in many other systems. For that, a current work is underway to improve the numerical accuracy of its DRMG calculation and explore different definitions.

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Section: A Model Hamiltonianmentioning

confidence: 99%

Transport in carbon nanotubes: Two-level SU(2) regime reveals subtle competition between Kondo and intermediate valence states

et al. 2011

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“…A prototype system where Fano physics may be observed consists of a single quantum dot side-coupled to a quantum wire [3][4][5][6][7][8][9][10][11][12][13][14][15] . The Fano line shape results from an interference of the quantum amplitudes for the conduction pathway directly through the quantum wire without passing through the quantum dot and the indirect conduction pathway via the quantum dot.…”

Section: Introductionmentioning

confidence: 99%

Fano-Kondo effect in side-coupled double quantum dots at finite temperatures and the importance of two-stage Kondo screening

Žitko

2010

Phys. Rev. B

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We study the zero-bias conductance through the system of two quantum dots, one of which is embedded directly between the source and drain electrodes, while the second dot is side-coupled to the first one through a tunneling junction. Modeling the system using the two-impurity Anderson model, we compute the temperaturedependence of the conductance in various parameter regimes using the numerical renormalization group. We consider the non-interacting case, where we study the extent of the departure from the conventional Fano resonance line shape at finite temperatures, and the case where the embedded and/or the side-coupled quantum dot is interacting, where we study the consequences of the coexistence of the Kondo and Fano effects. If the sidecoupled dot is very weakly interacting, the occupancy changes by two when the on-site energy crosses the Fermi level and a Fano-resonance-like shape is observed. If the interaction on the side-coupled dot is sizeable, the occupancy changes only by one and a very different line-shape results, which is strongly and characteristically temperature dependent. These results suggest an intriguing alternative interpretation of the recent experimental results study of the transport properties of the side-coupled double quantum dot [Sasaki et al., Phys. Rev. Lett. 103, 266806 (2009)]: the observed Fano-like conductance anti-resonance may, in fact, result from the two-stage Kondo effect in the regime where the experimental temperature is between the higher and the lower Kondo temperature.

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“…The situation is somehow different in multiple quantum dot systems where due to additional conduction channels one can observe more complex signatures of the Kondo and Fano effects [12][13][14][15][16]. In particular, in a two quantum dot system with one dot connected to the external leads and the other to the first dot but not to the external leads (T-shaped double-quantum-dot system), one has to account for a two state Kondo effect, as the localized spins in the system's component quantum dots are screened at different temperatures [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric transport properties of a T-shaped double quantum dot system in the Coulomb blockade regime

et al. 2014

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We investigate the thermoelectric properties of a T-shaped double quantum dot system described by a generalized Anderson Hamiltonian. The system's electrical conduction (G) and the fundamental thermoelectric parameters such as the Seebeck coefficient (S) and the thermal conductivity (κ), along with the system's thermoelectric figure of merit (ZT) are numerically estimated based on a Green's function formalism that includes contributions up to the Hartree-Fock level. Our results account for finite onsite Coulomb interaction terms in both component quantum dots and discuss various ways leading to an enhanced thermoelectric figure of merit for the system. We demonstrate that the presence of Fano resonances in the Coulomb blockade regime is responsible for a strong violation of the Wiedemann-Franz law and a considerable enhancement of the system's figure of merit (ZT ).

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Kondo and Dicke effect in quantum dots side coupled to a quantum wire

Cited by 37 publications

References 22 publications

Transport in carbon nanotubes: Two-level SU(2) regime reveals subtle competition between Kondo and intermediate valence states

Transport in carbon nanotubes: Two-level SU(2) regime reveals subtle competition between Kondo and intermediate valence states

Fano-Kondo effect in side-coupled double quantum dots at finite temperatures and the importance of two-stage Kondo screening

Thermoelectric transport properties of a T-shaped double quantum dot system in the Coulomb blockade regime

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