Publisher’s Note: First-Order<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mn>0</mml:mn><mml:mtext mathvariant="normal">−</mml:mtext><mml:mi>π</mml:mi></mml:math>Quantum Phase Transition in the Kondo Regime of a Superconducting Carbon-Nanotube Quantum Dot [Phys. Rev. X<b>2</b>, 011009 (2012)]

Maurand, Romain; Meng, Tobias; Bonet, Edgar; Florens, Serge; Marty, Laëtitia; Wernsdorfer, Wolfgang

doi:10.1103/physrevx.2.019901

Cited by 20 publications

(46 citation statements)

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“…There, a reversal of the supercurrent across the device is observed when the GS of the QD changes from singlet to doublet [5,[19][20][21]. However, the back gate evolution of ∆G max 1…”

Section: Non-local Conductance Correlationsmentioning

confidence: 99%

Nonlocal spectroscopy of Andreev bound states

et al. 2014

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We experimentally investigate Andreev bound states (ABSs) in a carbon nanotube quantum dot (QD) connected to a superconducting Nb lead (S). A weakly coupled normal metal contact acts as a tunnel probe that measures the energy dispersion of the ABSs. Moreover we study the response of the ABS to non-local transport processes, namely Cooper pair splitting and elastic co-tunnelling, that are enabled by a second QD fabricated on the same nanotube on the opposite side of S. We find an appreciable non-local conductance with a rich structure, including a sign reversal at the ground state transition from the ABS singlet to a degenerate magnetic doublet. We describe our device by a simple rate equation model that captures the key features of our observations and demonstrates that the sign of the non-local conductance is a measure for the charge distribution of the ABS, given by the respective Bogoliubov-de Gennes amplitudes u and v.

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“…There, a reversal of the supercurrent across the device is observed when the GS of the QD changes from singlet to doublet [5,[19][20][21]. However, the back gate evolution of ∆G max 1…”

Section: Non-local Conductance Correlationsmentioning

confidence: 99%

Nonlocal spectroscopy of Andreev bound states

et al. 2014

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“…The simplest techniques are based on static renormalization group ideas, and have been formulated both within a perturbative expansion in the effective Coulomb interaction in the framework of the functional renormalization group (fRG) 48,[85][86][87][88] , or around the large gap limit by a selfconsistent Andreev bound state picture (SCABS) 32,73,89 . Both techniques achieve surprisingly good agreement (in their range of validity) with full-scale numerical renormalization group (NRG) computations [90][91][92][93][94][95][96][97][98][99][100] , while their low numerical cost allows to efficiently explore the effective Andreev levels over the whole parameter space.…”

Section: Introductionmentioning

confidence: 99%

Magnetoelectric spectroscopy of Andreev bound states in Josephson quantum dots

et al. 2016

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We theoretically investigate the behavior of Andreev levels in a single-orbital interacting quantum dot in contact to superconducting leads, focusing on the effect of electrostatic gating and applied magnetic field, as relevant for recent experimental spectroscopic studies. In order to account reliably for spin-polarization effects in presence of correlations, we extend here two simple and complementary approaches that are tailored to capture effective Andreev levels: the static functional renormalization group (fRG) and the self-consistent Andreev bound states (SCABS) theory. We provide benchmarks against the exact large-gap solution as well as NRG calculations and find good quantitative agreement in the range of validity. The large flexibility of the implemented approaches then allows us to analyze a sizable parameter space, allowing to get a deeper physical understanding into the Zeeman field, electrostatic gate, and flux dependence of Andreev levels in interacting nanostructures.

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“…Carbon nanotubes (CNTs) have proved to be well suited for the observation of both Kondo effect 6,7,14,18 and ABS 4 because they fulfill three basic requirements: (i) At low enough temperatures (below 4 K) they behave as QDs whereby electron occupancy can be electrostatically tuned. (ii) Good S-X coupling with conventional superconductors (that can be turned into the normal state with a moderate magnetic field) were recently achieved, 2,3 and (iii) there is a possibility of simultaneous weak coupling to a probe that allows tunneling spectroscopy of ABS.…”

Section: A Sample Fabrication and Characterizationmentioning

confidence: 99%

“…6,7,[14][15][16][17][18] In this work, instead of relying on transport through a QD, we perform tunneling spectroscopy of a single QD (coupled to a superconducting reservoir) in order to investigate this interplay in a direct way. In particular, we explore how the Kondo resonance, observed when the QD's occupancy is odd and the reservoir is in the normal state, is replaced by ABS within the gap as the reservoir becomes superconducting.…”

Section: Introductionmentioning

confidence: 99%

To Screen or Not to Screen, That is the Question!

Maurand¹,

Schönenberger²

2013

Physics

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We performed tunneling spectroscopy of a carbon nanotube quantum dot (QD) coupled to a metallic reservoir either in the normal or in the superconducting state. We explore how the Kondo resonance, observed when the QD's occupancy is odd and the reservoir is normal, evolves towards Andreev bound states (ABS) in the superconducting state. Within this regime, the ABS spectrum observed is consistent with a quantum phase transition from a singlet to a degenerate magnetic doublet ground state, in quantitative agreement with a single-level Anderson model with superconducting leads.

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Publisher’s Note: First-Order0−πQuantum Phase Transition in the Kondo Regime of a Superconducting Carbon-Nanotube Quantum Dot [Phys. Rev. X2, 011009 (2012)]

Cited by 20 publications

References 0 publications

Nonlocal spectroscopy of Andreev bound states

Nonlocal spectroscopy of Andreev bound states

Magnetoelectric spectroscopy of Andreev bound states in Josephson quantum dots

To Screen or Not to Screen, That is the Question!

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