Finite-frequency noise in a quantum dot with normal and superconducting leads

Droste, Stephanie; Splettstoesser, Janine; Governale, Michele

doi:10.1103/physrevb.91.125401

Cited by 24 publications

(32 citation statements)

References 77 publications

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“…Further parameters are = −8Γ, U = 16Γ. The black solid lines are shown for reference and present results obtained with perturbation theory [20,21]. improvement.…”

Section: Tddft Noise Spectra Of the Interacting Mesoscopic Capacitormentioning

confidence: 94%

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Equilibrium finite-frequency noise of an interacting mesoscopic capacitor studied in time-dependent density functional theory

Dittmann

Splettstoesser

Helbig

2018

J. Phys.: Conf. Ser.

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We calculate the frequency-dependent equilibrium noise of a mesoscopic capacitor in time-dependent density functional theory (TDDFT). The capacitor is modeled as a singlelevel quantum dot with on-site Coulomb interaction and tunnel coupling to a nearby reservoir. The noise spectra are derived from linear-response conductances via the fluctuation-dissipation theorem. Thereby, we analyze the performance of a recently derived exchange-correlation potential with time-nonlocal density dependence in the finite-frequency linear-response regime. We compare our TDDFT noise spectra with real-time perturbation theory and find excellent agreement for noise frequencies below the reservoir temperature.

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“…Further parameters are = −8Γ, U = 16Γ. The black solid lines are shown for reference and present results obtained with perturbation theory [20,21]. improvement.…”

Section: Tddft Noise Spectra Of the Interacting Mesoscopic Capacitormentioning

confidence: 94%

“…As a reference, the black solid lines present the result of an analytic calculation based on perturbation theory, see e. g. Refs. [20,21]. This method applies an expansion in the tunnel coupling.…”

Section: Tddft Noise Spectra Of the Interacting Mesoscopic Capacitormentioning

confidence: 99%

Equilibrium finite-frequency noise of an interacting mesoscopic capacitor studied in time-dependent density functional theory

Dittmann

Splettstoesser

Helbig

2018

J. Phys.: Conf. Ser.

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“…Reference [164]-limited in the linear transport regime-points out that the effect of the interaction is to renormalize the coupling S and the dot level ε 0 in the regime U S . A similar approach was employed in S-QD-S [166,167] and N-QD-S [168,169] junctions which focused on the regime S N and in the large gap limit to discuss the effective Hamiltonian for the proximized quantum dot whose behavior is ruled by the ration U/ S . This approach predicts essentially that, when S N it is still possible to establish a BCS-like state in a single-level quantum dot even in the presence of Coulomb repulsion, i.e., U/ S < 1.…”

Section: Model and Approximationmentioning

confidence: 99%

Charge-vibration interaction effects in normal-superconductor quantum dots

2017

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We study the quantum transport and the nonequilibrium vibrational states of a quantum dot embedded between a normal-conducting and a superconducting lead with the charge on the quantum dot linearly coupled to a harmonic oscillator of frequency ω. To the leading order in the charge-vibration interaction, we calculate the current and the nonequilibrium phonon occupation by the Keldsyh Green's function technique. We analyze the inelastic, vibration-assisted tunneling processes in the regime ω < , with the superconducting energy gap , and for sharp resonant transmission through the dot. When the energy ε 0 of the dot's level is close to the Fermi energy μ, i.e., |ε 0 − μ| , inelastic vibration-assisted Andreev reflections dominate up to voltage eV . The inelastic quasiparticle tunneling becomes the leading process when the dot's level is close to the superconducting gap |ε 0 − μ| ∼ ± ω. In both cases, the inelastic tunneling processes appear as sharp and prominent peaks-not broadened by temperature-in the current-voltage characteristic and pave the way for inelastic spectroscopy of vibrational modes even at temperatures T ω. We also found that inelastic vibration-assisted Andreev reflections as well as quasiparticle tunneling induce a strong nonequilibrium state of the oscillator. In different ranges on the dot's level, we found that the current produces: (i) ground-state cooling of the oscillator with phonon occupation n 1, (ii) accumulation of energy in the oscillator with n 1, and (iii) a mechanical instability characterized by a negative damping coefficient. We show that ground-state cooling is achieved simultaneously for several modes of different frequencies. Finally, we discuss how the nonequilibrium vibrational state can be readily detected by the asymmetric behavior of the inelastic current peaks with respect to the gate voltage.

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“…Moreover, the frequency dependence of the noise spectrum can be related to energy emission and absorption processes, which has been demonstrated in transport through nanoscale devices in the stationary regime as well [15][16][17]. Theoretically, finite-frequency noise of quantum dots has been analyzed mostly for the stationary regime [18][19][20][21][22][23][24][25][26][27][28][29][30][31] and the study of time-dependent setups [32][33][34][35] has so far been limited to systems where Coulomb interaction seems to play no major role. In this paper, we study the finite-frequency noise of a slowly time-dependently driven quantum dot with possibly strong on-site Coulomb interaction, weakly tunnelcoupled to a single electron reservoir, as shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Finite-frequency noise of interacting single-electron emitters: Spectroscopy with higher noise harmonics

Dittmann

Splettstoesser

2018

Phys. Rev. B

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We derive the symmetrized current-noise spectrum of a quantum dot, which is weakly tunnelcoupled to an electron reservoir and driven by a slow time-dependent gate voltage. This setup can be operated as an on-demand emitter of single electrons into a mesoscopic conductor. By extending a real-time diagrammatic technique which is perturbative in the tunnel coupling, we obtain the timeresolved finite-frequency noise as well as its decomposition into noise harmonics in the presence of both strong Coulomb interaction and slow time-dependent driving. We investigate the noise over a large range of frequencies and point out where the interplay of Coulomb interaction and driving leads to unique signatures in finite-frequency noise spectra, in particular in the first harmonic. Besides that, we employ the first noise harmonic as a spectroscopic tool to access individual fluctuation processes. We discuss how the inverse noise frequency sets a time scale for fluctuations, which competes with time scales of the quantum-dot relaxation dynamics as well as the driving. arXiv:1805.03130v1 [cond-mat.mes-hall]

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Finite-frequency noise in a quantum dot with normal and superconducting leads

Cited by 24 publications

References 77 publications

Equilibrium finite-frequency noise of an interacting mesoscopic capacitor studied in time-dependent density functional theory

Equilibrium finite-frequency noise of an interacting mesoscopic capacitor studied in time-dependent density functional theory

Charge-vibration interaction effects in normal-superconductor quantum dots

Finite-frequency noise of interacting single-electron emitters: Spectroscopy with higher noise harmonics

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