Tunneling Spectroscopy of Andreev Energy Levels in a Quantum Dot Coupled to a Superconductor

Deacon, Russell; Tanaka, Yoïchi; Oiwa, A.; Sakano, Rui; Yoshida, Kenji; Shibata, Kenji; Hirakawa, Kazuomi; Tarucha, Seigo

doi:10.1103/physrevlett.104.076805

Cited by 224 publications

(263 citation statements)

References 27 publications

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“…Its slope is given by the capacitive crosstalk from the source contact. However, the reason for the conductance difference between ζ and −ζ, also observed in [4][5][6][7][8], remains unclear. One possible explanation might be a soft superconducting gap for which quasiparticle states at energies E < ∆ are available [23].…”

Section: Discussionmentioning

confidence: 99%

“…A natural experiment to measure the Andreev addition energy ζ = |E − − E ↑,↓ |, defined as the energy difference between ABS and magnetic doublet, uses a normal conducting tunnel probe (N) in a N-QD-S geometry. If the tunnel coupling between N and the QD, Γ N , is sufficiently weak, the influence of the tunnel probe on the QD-S excitation spectrum is negligible and the differential conductance across the device, G = ∂I/∂V SD , shows a peak for |eV SD | = ζ [4][5][6][7][8][9].…”

Section: Local Spectroscopy Of Absmentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

Section: Local Spectroscopy Of Absmentioning

confidence: 99%

Nonlocal spectroscopy of Andreev bound states

et al. 2014

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“…This model exhibits also a transition to a degenerate S = 1/2 ground state and its spectral properties are relevant to understand the transport properties in N-QD-S systems when Γ N ≪ ∆ [22]. To obtain the numerically exact ABS spectrum for this case we have implemented an NRG algorithm following the lines of Refs.…”

Section: Abs Spectrum For the S-qd Casementioning

confidence: 99%

The Andreev states of a superconducting quantum dot: mean field versus exact numerical results

Martín‐Rodero

Yeyati

2012

J. Phys.: Condens. Matter

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Esta es la versión de autor del artículo publicado en: This is an author produced version of a paper published in: El acceso a la versión del editor puede requerir la suscripción del recurso Access to the published version may require subscriptionThe Andreev states of a superconducting quantum dot: mean field vs exact numerical results A. Martín-Rodero and A. Levy Yeyati Departamento de Física Teórica de la Materia Condensada and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, E-28049 Madrid, SpainWe analyze the spectral density of a single level quantum dot coupled to superconducting leads focusing on the Andreev states appearing within the superconducting gap. We use two complementary approaches: the numerical renormalization group and the Hartree-Fock approximation. Our results show the existence of up to four bound states within the gap when the ground state is a spin doublet (π phase). Furthermore the results demonstrate the reliability of the mean field description within this phase. This is understood from a complete correspondence that can be established between the exact and the mean field quasiparticle excitation spectrum within the gap.

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“…In various experimental realizations of the quantum dots (such as self-assembled InAs islands [25], carbon nanotubes [26,27] or semiconducting nanowires [28,29]) attached to the superconducting leads the energy gap ∆ was safely smaller than the repulsion potential U . For this reason, in the subgap Andreev spectroscopy the correlations hardly contributed any Coulomb blockade.…”

Section: Correlation Effectsmentioning

confidence: 99%

Enhancements of the Andreev conductance due to emission/absorption of bosonic quanta

Barański

Domański

2015

J. Phys.: Condens. Matter

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We analyze the subgap spectrum and transport properties of the quantum dot embedded between one superconducting and another metallic reservoirs and additionally coupled to an external boson mode. Emission/absorption of the bosonic quanta induces a series of the subgap Andreev states, that eventually interfere with each other. We discuss their signatures in the differential conductance both, for the linear and nonlinear regimes.

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Tunneling Spectroscopy of Andreev Energy Levels in a Quantum Dot Coupled to a Superconductor

Cited by 224 publications

References 27 publications

Nonlocal spectroscopy of Andreev bound states

Nonlocal spectroscopy of Andreev bound states

The Andreev states of a superconducting quantum dot: mean field versus exact numerical results

Enhancements of the Andreev conductance due to emission/absorption of bosonic quanta

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