Muñoz, Bolech, and Kirchner Reply:

Muñoz, Enrique; Bolech, C. J.; Kirchner, Stefan

doi:10.1103/physrevlett.111.089702

Cited by 31 publications

(64 citation statements)

References 7 publications

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“…2. From previous results it is known that the differential conductance ∂j/∂φ is not affected by this difference, since it shows qualitatively the same functional dependence on T as on φ 47,48,54,66,67,128,129 . The question arises whether this holds true also for ∂j/∂(∆T ).…”

Section: Resultsmentioning

confidence: 86%

“…In particular, we focused on the differential response of the current to a temperature gradient ∂j/∂(∆T ) in the nonequilibrium Kondo regime (φ = 0 and T < T K ), for the case of an infinitesimal temperature difference d(∆T ). When compared to the results for the differential conductance ∂j/∂φ known from previous studies 47,48,54,66,67,128,129 , we find that ∂j/∂(∆T ) exhibits a more complex behavior. On the one hand, the equilibrium and nonequilibrium properties turn out to be quite different, i.e.…”

Section: Discussionmentioning

confidence: 88%

“…While the electronic transport has been studied extensively, the thermoelectric transport theory mostly focused on the linear response regime 13,25,[71][72][73][74][75][76][77][78][79][80][81][82][83][84][85][86][87][88][89] . The nonlinear regime has been addressed mainly in the weak coupling limit 32,78,[90][91][92][93][94][95][96][97] , a systematic analysis including renormalization effects 66,67,98,99 beyond the perturbative regime is still missing. Recent findings 90,99 indicate a Seebeck coefficient which is enhanced with respect to the equilibrium result.…”

Section: Introductionmentioning

confidence: 99%

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Thermoelectric response of a correlated impurity in the nonequilibrium Kondo regime

et al. 2016

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We study nonequilibrium thermoelectric transport properties of a correlated impurity connected to two leads for temperatures below the Kondo scale. At finite bias, for which a current flows across the leads, we investigate the differential response of the current to a temperature gradient. In particular, we compare the influence of a bias voltage and of a finite temperature on this thermoelectric response. This is of interest from a fundamental point of view to better understand the two different decoherence mechanisms produced by a bias voltage and by temperature. Our results show that in this respect the thermoelectric response behaves differently from the electric conductance. In particular, while the latter displays a similar qualitative behavior as a function of voltage and temperature, both in theoretical and experimental investigations, qualitative differences occur in the case of the thermoelectric response. In order to understand this effect, we analyze the different contributions in connection to the behavior of the impurity spectral function versus temperature. Especially in the regime of strong interactions and large enough bias voltages we obtain a simple picture based on the asymmetric suppression or enhancement of the split Kondo peaks as a function of the temperature gradient. Besides the academic interest, these studies could additionally provide valuable information to assess the applicability of quantum dot devices as responsive nanoscale temperature sensors.

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Section: Resultsmentioning

confidence: 86%

Section: Discussionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

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Thermoelectric response of a correlated impurity in the nonequilibrium Kondo regime

et al. 2016

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“…22 and 23) or the dual-fermion superperturbation theory. 24 Finally, perturbative renormalization group studies have mostly started from the Kondo-model mapping of the Anderson model, either working with Keldysh Green's functions 25 or the reduced density operator approach. 26,27 The density operator approach has a long history in various fields of physics and chemistry.…”

Section: Introductionmentioning

confidence: 99%

Fermionic superoperators for zero-temperature nonlinear transport: Real-time perturbation theory and renormalization group for Anderson quantum dots

2012

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We study electron quantum transport through a strongly interacting Anderson quantum dot at finite bias voltage and magnetic field at zero temperature using the real-time renormalization group (RT-RG) in the framework of a kinetic (generalized master) equation for the reduced density operator. To this end, we further develop the general, finite-temperature real-time transport formalism by introducing field superoperators that obey fermionic statistics. This direct second quantization in Liouville Fock space strongly simplifies the construction of operators and superoperators that transform irreducibly under the Anderson-model symmetry transformations. The fermionic field superoperators naturally arise from the univalence (fermion-parity) superselection rule of quantum mechanics for the total system of quantum dot plus reservoirs. Expressed in these field superoperators, the causal structure of the perturbation theory for the effective time-evolution superoperator kernel becomes explicit. Using the constraints of the causal structure, we construct a parametrization of the exact effective time-evolution kernel for which we analytically find the eigenvectors and eigenvalues in terms of a minimal set of only 30 independent coefficients. The causal structure also implies the existence of a fermion-parity protected eigenvector of the exact Liouvillian, explaining a recently reported result on adiabatic driving [Contreras-Pulido et al., Phys. Rev. B 85, 075301 (2012)] and generalizing it to arbitrary order in the tunnel coupling . Furthermore, in the wide-band limit, the causal representation exponentially reduces the number of diagrams for the time-evolution kernel. The remaining diagrams can be identified simply by their topology and are manifestly independent of the energy cutoff term by term. By an exact reformulation of this series, we integrate out all infinite-temperature effects, obtaining an expansion targeting only the nontrivial, finite-temperature corrections, and the exactly conserved transport current follows directly from the time-evolution kernel. From this new series, the previously formulated RT-RG equations are obtained naturally. We perform a complete one-plus-two-loop RG analysis at finite voltage and magnetic field, while systematically accounting for the dependence of all renormalized quantities on both the quantum dot and reservoir frequencies. Using the second quantization in Liouville space and symmetry restrictions, we obtain analytical RT-RG equations, which can be solved numerically in an efficient way, and we extensively study the model parameter space, excluding the Kondo regime where the one-plus-two-loop approach is obviously invalid. The incorporated renormalization effects result in an enhancement of the inelastic cotunneling peak, even at a voltage ∼magnetic field ∼tunnel coupling . Moreover, we find a tunnel-induced nonlinearity of the stability diagrams (Coulomb diamonds) at finite voltage, both in the single-electron tunneling and inelastic cotunneling regime.

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“…Approximation (32) provides some insight into the physics of the hybrid structures discussed in this work but other advanced techniques 67 would be needed to describe an interplay between the Kondo and Andreev effects 4 on a some qualitative level. Analysis of the Kondo correlations 56,68 under the non-equilibrium conditions 69 can be done, for instance using the suitably generalized non-crossing approximation 66,67 or the numerical renormalization group approach 34,70 . Let us recall 56 that within EOM method the optimal conditions for enhancing the Andreev conductance by the Kondo resonance occur when Γ S ∼ Γ L .…”

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confidence: 99%

Interplay between direct and crossed Andreev reflections in hybrid nanostructures

et al. 2013

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The interplay between various many body effects in a quantum dot attached to two normal and one superconducting lead is considered in the limit of large superconducting gap. By the proximity effect the superconducting lead induces pairing correlations on the quantum dot. In the subgap region one observes the anomalous tunneling via direct and crossed Andreev scattering, whereas the usual single particle electronic transfer is suppressed. The interactions of electrons on the dot leading to such phenomena as the Coulomb blockade and the Kondo effect severely modify the currents flowing in the system. In particular: (i) they prevent the existence of the negative differential conductance observed for non-interacting quantum dot over the whole range of voltages, (ii) affect the distribution of the currents as function of the applied voltage and (iii) lead to the appearance of additional low bias feature due to the formation of the Abrikosov-Suhl resonance. The non-local correlations in the Coulomb blockade regime are most pronounced for the particle-hole symmetric dot and thus can be easily tuned by means of gate voltage. They are observed even in the Kondo regime and dominate the behavior close to the Abrikosov-Suhl resonance showing convincingly that Kondo correlations do not destroy subtle entanglement between electrons.

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Muñoz, Bolech, and Kirchner Reply:

Cited by 31 publications

References 7 publications

Thermoelectric response of a correlated impurity in the nonequilibrium Kondo regime

Thermoelectric response of a correlated impurity in the nonequilibrium Kondo regime

Fermionic superoperators for zero-temperature nonlinear transport: Real-time perturbation theory and renormalization group for Anderson quantum dots

Interplay between direct and crossed Andreev reflections in hybrid nanostructures

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