Signatures of nonlocal Cooper-pair transport and of a singlet-triplet transition in the critical current of a double-quantum-dot Josephson junction

Probst, Benedikt; Domínguez, Fernándo; Schroer, Alexander; Yeyati, A. Levy; Recher, Patrik

doi:10.1103/physrevb.94.155445

Cited by 29 publications

(23 citation statements)

References 52 publications

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“…[42] and [43] for recent reviews on experiments and theory, respectively. In particular, there are investigations of the Josephson effect through quantum dots [44][45][46][47][48][49], multiple Andreev reflections [50][51][52][53][54][55], the interplay between superconducting correlations and the Kondo effect [56][57][58][59][60][61], the generation of unconventional superconducting correlations in quantum dots [62][63][64][65], Cooper pair splitting [66][67][68][69][70][71] and the generation of Majorana fermions [72][73][74][75]. Thermoelectric effects in superconductor-quantum dot hybrids have been studied in the absence of Coulomb interactions [76].…”

Section: Introductionmentioning

confidence: 99%

Phase-dependent heat and charge transport through superconductor–quantum dot hybrids

Kamp

Sothmann

2019

Phys. Rev. B

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We analyze heat and charge transport through a single-level quantum dot coupled to two BCS superconductors at different temperatures to first order in the tunnel coupling. In order to describe the system theoretically, we extend a real-time diagrammatic technique that allows us to capture the interplay between superconducting correlations, strong Coulomb interactions and nonequilibrium physics. We find that a thermoelectric effect can arise due to the superconducting proximity effect on the dot. In the nonlinear regime, the thermoelectric current can also flow at the particle-hole symmetric point due to a level renormalization caused by virtual tunneling between the dot and the leads. The heat current through the quantum dot is sensitive to the superconducting phase difference. In the nonlinear regime, the system can act as a thermal diode. arXiv:1809.09428v3 [cond-mat.mes-hall]

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Section: Introductionmentioning

confidence: 99%

Phase-dependent heat and charge transport through superconductor–quantum dot hybrids

Kamp

Sothmann

2019

Phys. Rev. B

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“…These ground states can be obtained by tuning the DQD energy, ε δ > 0 corresponding to empty quantum dot, and ε δ < 0 corresponding to the single electron occupation. In the case where the quantum dots are singly occupied we consider only singlet state since it is the ground state of DQD in the strong Coulomb interaction limit 44 . It can also be shown that the nonlocal contribution to the Josephson current is absent for |T 0 , |↑↑ , |↓↓ DQD ground states when U → ∞ 49 .…”

Section: Josephson Currentmentioning

confidence: 99%

“…In addition, we assume that k B T ≪ J, therefore we can neglect the thermal excitation of the triplet states. Here J denotes the exchange interaction between the quantum dots (via superconducting electrodes) that can be also calculated with the 4-th order perturbation theory 44,49 . Since we consider the superconducting electrodes with the superconducting gap ∆ in the quasiparticle density of states with assumption ∆ ≫ k B T K one can neglect the effect of Kondo correlations on the value of the exchange interaction J.…”

Section: Josephson Currentmentioning

confidence: 99%

Aharonov-Bohm and Aharonov-Casher effects in a double quantum dot Josephson junction

et al. 2018

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We analyze a Josephson junction between two superconductors interconnected through a normalstate nanostructure made of two parallel nanowires with embedded quantum dots. We study the influence of interference effects due to the Aharonov-Bohm (AB) and Aharonov-Casher (AC) phases for local and nonlocal (split) Cooper pairs. In the AB effect the phase of electron is affected by magnetic flux, while in the AC effect the phase of the electron in solid state can be modified due to the Rashba spin-orbit coupling. In the low-transmission regime the AB and AC effects can be related to only local or nonlocal Cooper pair transport, respectively. We demonstrate that by the addition of the quantum dots the Cooper pair splitting can be made perfectly efficient, and that the AC phase is different for non-spin-flip and spin-flip transport processes.

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“…Several previous works on similar systems completely neglect the possibility of EC processes [7,52–54 71–72]. In other works EC coupling is taken into account [44,61,64–65 67–68 73], but in most of the cases it is defined as a constant coupling term that is equivalent to the IT coupling used here, therefore they can be incorporated to the same term. However, as we demonstrate below, in certain models the EC term is not constant, but it can depend on the on-site energies of the QDs.…”

Section: Introductionmentioning

confidence: 99%

Transport signatures of an Andreev molecule in a quantum dot–superconductor–quantum dot setup

Scherübl¹,

Pályi²,

Csonka³

2019

Beilstein J. Nanotechnol.

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Hybrid devices combining quantum dots with superconductors are important building blocks of conventional and topological quantum-information experiments. A requirement for the success of such experiments is to understand the various tunneling-induced non-local interaction mechanisms that are present in the devices, namely crossed Andreev reflection, elastic co-tunneling, and direct interdot tunneling. Here, we provide a theoretical study of a simple device that consists of two quantum dots and a superconductor tunnel-coupled to the dots, often called a Cooper-pair splitter. We study the three special cases where one of the three non-local mechanisms dominates, and calculate measurable ground-state properties, as well as the zero-bias and finite-bias differential conductance characterizing electron transport through this device. We describe how each non-local mechanism controls the measurable quantities, and thereby find experimental fingerprints that allow one to identify and quantify the dominant non-local mechanism using experimental data. Finally, we study the triplet blockade effect and the associated negative differential conductance in the Cooper-pair splitter, and show that they can arise regardless of the nature of the dominant non-local coupling mechanism. Our results should facilitate the characterization of hybrid devices, and their optimization for various quantum-information-related experiments and applications.

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Signatures of nonlocal Cooper-pair transport and of a singlet-triplet transition in the critical current of a double-quantum-dot Josephson junction

Cited by 29 publications

References 52 publications

Phase-dependent heat and charge transport through superconductor–quantum dot hybrids

Phase-dependent heat and charge transport through superconductor–quantum dot hybrids

Aharonov-Bohm and Aharonov-Casher effects in a double quantum dot Josephson junction

Transport signatures of an Andreev molecule in a quantum dot–superconductor–quantum dot setup

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