Signatures of the Higgs mode in transport through a normal-metal–superconductor junction

Tang, Gaomin; Belzig, Wolfgang; Zülicke, U.; Bruder, Christoph

doi:10.1103/physrevresearch.2.022068

Cited by 10 publications

(3 citation statements)

References 48 publications

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“…Signatures of the Higgs mode in the charge current of a superconductor-normal metal tunnel junction were reported in Ref. [23]. Superconductors can induce superconducting correlations in nearby nonsuperconducting materials via the proximity effect.…”

Section: Introductionmentioning

confidence: 80%

Pair-amplitude dynamics in strongly-coupled superconductor-quantum dot hybrids

Heckschen,

Sothmann

2021

Preprint

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We consider a three-terminal system consisting of a quantum dot strongly coupled to two superconducting reservoirs in the infinite gap limit and weakly coupled to a normal metal. Using a real-time diagrammatic approach, we calculate the dynamics of the proximity-induced pair amplitude on the quantum dot. We find that after a quench the pair amplitude shows pronounced oscillations with a frequency determined by the coupling to the superconductors. In addition, it decays exponentially on a time scale set by the coupling to the normal metal. Strong oscillations of the pair amplitude occur also when the system is periodically driven both in the adiabatic and fast-driving limit. We relate the dynamics of the pair amplitude to the Josephson and Andreev current through the dot to demonstrate that it is an experimentally accessible quantity.

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Section: Introductionmentioning

confidence: 80%

Pair-amplitude dynamics in strongly-coupled superconductor-quantum dot hybrids

Heckschen,

Sothmann

2021

Preprint

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“…Irrespective of microscopic models of the Dynes formula, we can incorporates Γ into the quasiclassical formalism of the BCS theory (see e.g., Refs. [21,22,[38][39][40][41]). Also, microscopic derivations of the Dynes formula have been investigated [42,43].…”

Section: Introductionmentioning

confidence: 99%

Effects of nonmagnetic impurities and subgap states on the kinetic inductance, complex conductivity, quality factor and depairing current density

Kubo

2021

Preprint

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We investigate how a combination of a nonmagnetic-impurity scattering rate γ and finite subgap states parametrized by Dynes Γ affects various physical quantities relevant to to superconducting devices: kinetic inductance L k , complex conductivity σ, surface resistance Rs, quality factor Q, and depairing current density J d . All the calculations are based on the Eilenberger formalism of the BCS theory. We assume the device materials are extreme type-II s-wave superconductors. It is well known that the optimum impurity concentration (γ/∆0 ∼ 1) minimizes Rs. Here, ∆0 is the pair potential for the idealized (Γ → 0) superconductor for the temperature T → 0. We find the optimum Γ can also reduce Rs by one order of magnitude for a clean superconductor (γ/∆0 < 1) and a few tens % for a dirty superconductor (γ/∆0 > 1). Also, we find a nearly-ideal (Γ/∆0 ≪ 1) clean-limit superconductor exhibits a frequency-independent Rs for a broad range of frequency ω, which can significantly improve Q of a very compact cavity with a few tens of GHz frequency. As Γ or γ increases, the plateau disappears, and Rs obeys the ω 2 dependence. The subgap-state-induced residual surface resistance Rres is also studied, which can be detected by an SRF-grade high-Q 3D resonator. We calculate L k (γ, Γ, T ) and J d (γ, Γ, T ), which are monotonic increasing and decreasing functions of (γ, Γ, T ), respectively. Measurements of (γ, Γ) of device materials can give helpful information on engineering (γ, Γ) via materials processing, by which it would be possible to improve Q, engineer L k , and ameliorate J d .

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“…Additional theoretical works have studied the Higgs mode in unconventional superconductors [22] as well as the interplay of Higgs and Leggett modes in multi-band superconductors [23,24]. Furthermore, the occurrence of Higgs mode in superconductor-normal metal junctions [25] and its signatures in transport properties have been analyzed [26]. Recent reviews on Higgs physics in superconductors can be found in Refs.…”

Section: Introductionmentioning

confidence: 99%

Higgs-like pair amplitude dynamics in superconductor-quantum dot hybrids

Kamp,

Sothmann

2020

Preprint

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We consider a quantum dot weakly tunnel coupled to superconducting reservoirs. A finite superconducting pair amplitude can be induced on the dot via the proximity effect. We investigate the dynamics of the induced pair amplitude after a quench and under periodic driving of the system by means of a real-time diagrammatic approach. We find that the quench dynamics is dominated by an exponential decay towards equilibrium. In contrast, the periodically driven system can sustain coherent oscillations of both the amplitude and the phase of the induced pair amplitude in analogy to Higgs and Nambu-Goldstone modes in driven bulk superconductors.

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Signatures of the Higgs mode in transport through a normal-metal–superconductor junction

Cited by 10 publications

References 48 publications

Pair-amplitude dynamics in strongly-coupled superconductor-quantum dot hybrids

Pair-amplitude dynamics in strongly-coupled superconductor-quantum dot hybrids

Effects of nonmagnetic impurities and subgap states on the kinetic inductance, complex conductivity, quality factor and depairing current density

Higgs-like pair amplitude dynamics in superconductor-quantum dot hybrids

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