Spin-orbital Kondo decoherence by environmental effects in capacitively coupled quantum dots

Andergassen, Sabine; Simon, Pascal; Florens, Serge; Feinberg, Denis

doi:10.1103/physrevb.77.045309

Cited by 3 publications

(2 citation statements)

References 44 publications

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“…Only recently has this longrange interaction attracted more widespread attention of experimental and theory groups alike. [38][39][40][41][42][43] The T-shape configuration, where two QDs are mutually coupled via a tunneling matrix element, while only one of them is coupled to metallic contacts, has attracted considerable interest as it allows the study of the two stage Kondo (TSK) effect, and interference phenomena as the Fano effect 23,[44][45][46][47] by fine control of the inter-dot tunnel coupling. This effect results from the progressive screening of the localized spin of the electron in each QD as the system is cooled down to very low temperatures.…”

Section: Introductionmentioning

confidence: 99%

Capacitively coupled double quantum dot system in the Kondo regime

et al. 2011

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A detailed study of the low-temperature physics of an interacting double quantum dot system in a T-shape configuration is presented. Each quantum dot is modeled by a single Anderson impurity and we include an inter-dot electron-electron interaction to account for capacitive coupling that may arise due to the proximity of the quantum dots. By employing a numerical renormalization group approach to a multi-impurity Anderson model, we study the thermodynamical and transport properties of the system in and out of the Kondo regime. We find that the two-stage-Kondo effect reported in previous works is drastically affected by the inter-dot Coulomb repulsion. In particular, we find that the Kondo temperature for the second stage of the two-stage-Kondo effect increases exponentially with the inter-dot Coulomb repulsion, providing a possible path for its experimental observation.

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Section: Introductionmentioning

confidence: 99%

Capacitively coupled double quantum dot system in the Kondo regime

et al. 2011

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“…The focus of our study is the structure with the next to single QD complexity level -which is besides slight modifications and similar geometries 2-5 a double QD structure in parallel geometry. [6][7][8][9][10][11][12][13][14][15] The most widespread modeling strategy for a QD is the bottom-up approach. The structure is essentially assumed to be a zero-dimensional object, which is modeled by a single spin-degenerate fermionic level.…”

Section: Introductionmentioning

confidence: 99%

Nonequilibrium transport properties of a double quantum dot in the Kondo regime

Breyel

Komnik

2011

Phys. Rev. B

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We analyze the nonequilibrium transport properties of a parallel double quantum dot in terms of its full counting statistics (FCS). The parameters of the setup are assumed to be such that both subsystems are driven into the Kondo regime. After a series of transformations the Hamiltonian is then mapped onto a Majorana resonant level model, which effectively describes the Toulouse point of the respective double impurity two-terminal Kondo model. Its FCS is then obtained at arbitrary constellation of voltage, temperature, and local magnetic fields. We identify two different transport processes corresponding to single electron tunneling as well as an electron pair process and give the respective effective transport coefficients. In the most universal linear response regime the FCS turns out to be of a binomial shape with an effective transmission coefficient. Furthermore, we find a complete transport suppression (antiresonance) at a certain parameter constellation, which is similar to the one found in the noninteracting quantum dots. By an explicit expansion around the Toulouse point we show that the antiresonance is universal and should be observable in the generic Kondo dot setup. We discuss experimental implications of our predictions as well as possible routes for generalizations of our approach.

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Entanglement entropy and quantum phase transitions in quantum dots coupled to Luttinger liquid wires

2011

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We study a quantum phase transition which occurs in a system composed of two impurities (or quantum dots) each coupled to a different interacting (Luttinger-liquid) lead. While the impurities are coupled electrostatically, there is no tunneling between them. Using a mapping of this system onto a Kondo model, we show analytically that the system undergoes a Berezinskii-Kosterlitz-Thouless quantum phase transition as function of the Luttinger liquid parameter in the leads and the dot-lead interaction. The phase with low values of the Luttinger-liquid parameter is characterized by an abrupt switch of the population between the impurities as function of a common applied gate voltage. However, this behavior is hard to verify numerically since one would have to study extremely long systems. Interestingly though, at the transition the entanglement entropy drops from a finite value of ln(2) to zero. The drop becomes sharp for infinite systems. One can employ finite size scaling to extrapolate the transition point and the behavior in its vicinity from the behavior of the entanglement entropy in moderate size samples. We employ the density matrix renormalization group numerical procedure to calculate the entanglement entropy of systems with lead lengths of up to 480 sites. Using finite size scaling we extract the transition value and show it to be in good agreement with the analytical prediction.

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Spin-orbital Kondo decoherence by environmental effects in capacitively coupled quantum dots

Cited by 3 publications

References 44 publications

Capacitively coupled double quantum dot system in the Kondo regime

Capacitively coupled double quantum dot system in the Kondo regime

Nonequilibrium transport properties of a double quantum dot in the Kondo regime

Entanglement entropy and quantum phase transitions in quantum dots coupled to Luttinger liquid wires

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