Amplitude Higgs Mode and Admittance in Superconductors with a Moving Condensate

Moor, Andreas; Volkov, A. N.; Efetov, K. B.

doi:10.1103/physrevlett.118.047001

Cited by 74 publications

(76 citation statements)

References 56 publications

(120 reference statements)

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“…However, as we have shown recently, 32 the situation changes in the presence of the condensate flow. In this case, even a weak ac field E(t ) leads to a perturbation of ∆, δ∆ Ω ∝ Q Ω Q 0 , where Q 0 = mv 0 is the condensate momentum, v 0 is the velocity of the condensate, and Q Ω is the ac condensate momentum induced by the electric field E Ω according to the expression…”

Section: δ∆(T ) ∝ δ∆(0)mentioning

confidence: 88%

“…The hump in the obtained dependence Y ′ (Ω) is much broader than the peak in absorption in a current-carrying superconductor. 32 The mechanisms causing these maxima are different. In the first case, the maximum stems from excitation of quasiparticles with energy range defined by Eq.…”

Section: Discussionmentioning

confidence: 99%

“…In the second case, in Ref. 32, the peak is related to a resonance excitation of the Higgs mode by an ac field.…”

Section: Discussionmentioning

confidence: 99%

“…These equations were employed in our previous work for analysis of a uniform case 32 and will be used for calculating the admittance of a non-uniform superconductor, i.e., a short S-c-S JJ. We have shown earlier that the AM can be excited even by a weak ac field E(t ) in the presence of a condensate flow.…”

Section: Basic Equationsmentioning

confidence: 99%

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Alternating-current properties of short Josephson weak links

Moor

Volkov

2017

Phys. Rev. B

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We calculate the admittance of two types of Josephson weak links-the first is a one-dimensional superconducting wire with a local suppression of the order parameter, and the second is a short S-c-S structure, where S denotes a superconducting reservoir and c is a constriction. The systems of the first type are analyzed on the basis of time-dependent Ginzburg-Landau equations derived by Gor'kov and Eliashberg for gapless superconductors with paramagnetic impurities. It is shown that the impedance Z (Ω) has a maximum as a function of the frequency Ω, and the electric field E Ω is determined by two gauge-invariant quantities. One of them is the condensate momentum Q Ω and another is a potential µ related to charge imbalance. The structures of the second type are studied on the basis of microscopic equations for quasiclassical Green's functions in the Keldysh technique. For short S-c-S contacts (the Thouless energy E Th = D/L 2 ≫ ∆) we present a formula for admittance Y valid frequencies Ω and temperatures T less than the Thouless energy E Th (ħΩ,T ≪ E Th ) but arbitrary with respect to the energy gap ∆. It is shown that, at low temperatures, the absorption is absent [Re(Y ) = 0] if the frequency does not exceed the energy gap in the center of the constriction (Ω < ∆ cos ϕ 0 , where 2ϕ 0 is the phase difference between the S reservoirs). The absorption gradually increases with increasing the difference (Ω − ∆ cos ϕ 0 ) if 2ϕ 0 is less than the phase difference 2ϕ c corresponding to the critical Josephson current. In the interval 2ϕ c < 2ϕ 0 < π, the absorption has a maximum. This interval of the phase difference is achievable in phase-biased Josephson junctions. Close to T c the admittance has a maximum at low Ω which is described by an analytical formula.

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Section: δ∆(T ) ∝ δ∆(0)mentioning

confidence: 88%

Section: Discussionmentioning

confidence: 99%

“…In the second case, in Ref. 32, the peak is related to a resonance excitation of the Higgs mode by an ac field.…”

Section: Discussionmentioning

confidence: 99%

Section: Basic Equationsmentioning

confidence: 99%

See 2 more Smart Citations

Alternating-current properties of short Josephson weak links

Moor

Volkov

2017

Phys. Rev. B

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“…the second harmonic measurements has been recently for the current carrying states [35]. In this Letter we address an important effect of the quasiparticle spectrum of the superconducting system on long-time dynamic properties of Higgs modes and apply it to a system with proximity induced superconducting gap.…”

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confidence: 99%

Higgs modes in proximized superconducting systems

2019

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The proximity effect in hybrid superconducting -normal metal structures is shown to affect strongly the coherent oscillations of the superconducting order parameter ∆ known as the Higgs modes. The standard Higgs mode at the frequency 2∆ is damped exponentially by the quasiparticle leakage from the primary superconductor. Two new Higgs modes with the frequencies depending on both the primary and induced gaps in the hybrid structure are shown to appear due to the coherent electron transfer between the superconductor and the normal metal. Altogether these three modes determine the long-time asymptotic behavior of the superconducting order parameter disturbed either by the electromagnetic pulse or the quench of the system parameters and, thus, are of crucial importance for the dynamical properties and restrictions on the operating frequencies for superconducting devices based on the proximity effect used, e.g., in quantum computing, in particular, with topological low-energy excitations.The progress of modern nanotechnology opens new horizons for engineering superconducting correlations in various hybrid structures and creating, in fact, novel types of artificial superconducting materials with controllable properties [1][2][3][4][5][6][7][8][9][10][11]. The proximity phenomenon arising in a non-superconducting material from the electron exchange with a primary superconductor can generate the induced superconducting ordering in a wide class of materials, including unconventional ones [1][2][3][4][5][8][9][10][11]. The resulting superconducting state in these materials can controllably reveal the exotic properties very rarely found in natural metals or alloys and strongly different from the ones of the primary superconductor. The induced Cooper pairs can change, e.g., their spin structure from the singlet to a triplet one in the presence of strong spin-orbit coupling and Zeeman (or exchange) field [1,9,10] This spin transformation affects, of course, the momentum space structure of pairs: the routine swave condensate can turn into an exotic p-wave one. The resulting Cooper pair structure leads to the formation of topological low-energy excitations such as Majorana fermions [1,[9][10][11] and possesses a high potential for the development of new types of nanoelectronic devices perspective for applications in quantum computing, quantum information processing, quantum annealing, quantum memory and others [9,10].No wonder that the study of both equilibrium and nonequilibrium spectral and transport properties of these systems with engineered superconducting state has become recently one of the central research directions in condensed matter physics. While dc properties of these structures have been investigated in numerous theoretical and experimental works, the dynamic effects and, in particular, high frequency response remains an appealing problem which definitely deserves deeper understanding. Indeed, the limitations on the operating frequencies for above mentioned proximized devices [12][13][14][15][16][17] can be solel...

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Collective dynamics and the Anderson-Higgs mechanism in a bona fide holographic superconductor

Jeong

Baggioli

Kim

et al. 2023

J. High Energ. Phys.

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The holographic superconductor is one of the most popular models in the context of applied holography. Despite what its name suggests, it does not describe a superconductor. On the contrary, the low temperature phase of its dual field theory is a superfluid with a spontaneously broken U(1) global symmetry. As already observed in the previous literature, a bona fide holographic superconductor can be constructed using mixed boundary conditions for the bulk gauge field. By exploiting this prescription, we study the near-equilibrium collective dynamics in the Higgs phase and reveal the characteristic features of the Anderson-Higgs mechanism. We show that second sound disappears from the spectrum and the gauge field acquires a finite energy gap of the order of the plasma frequency. We observe an overdamped to underdamped crossover for the Higgs mode which acquires a finite energy gap below ≈ Tc/2, with Tc the superconducting critical temperature. Interestingly, the energy gap of the Higgs mode at low temperature is significantly smaller than 2∆, with ∆ the superconducting energy gap. Finally, we interpret our results using Ginzburg-Landau theory and we confirm the validity of previously derived perturbative analytic expressions.

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Amplitude Higgs Mode and Admittance in Superconductors with a Moving Condensate

Cited by 74 publications

References 56 publications

Alternating-current properties of short Josephson weak links

Alternating-current properties of short Josephson weak links

Higgs modes in proximized superconducting systems

Collective dynamics and the Anderson-Higgs mechanism in a bona fide holographic superconductor

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