Microscopic nonequilibrium theory of double-barrier Josephson junctions

Brinkman, Alexander; Golubov, Alexandre Avraamovitch; Rogalla, Horst; Wilhelm, Frank K.; Kupriyanov, M. Yu.

doi:10.1103/physrevb.68.224513

Cited by 53 publications

(53 citation statements)

References 52 publications

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“…(2) (see discussion in Ref. 18). The problem essentially simplifies if the distance eV between the harmonics is much smaller than the smallest scale δ E of variations in the quasiparticle spectrum,…”

Section: Model and Basic Equationsmentioning

confidence: 99%

Nonequilibrium effects in tunnel Josephson junctions

et al. 2005

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We study nonequilibrium effects in current transport through voltage biased tunnel junction with long diffusive superconducting leads at low applied voltage, eV ≪ 2∆, and finite temperatures. Due to a small value of the Josephson frequency, the quasiparticle spectrum adiabatically follows the time evolution of the superconducting phase difference, which results in the formation of oscillating bound states in the vicinity of the tunnel junction (Andreev band). The quasiparticles trapped by the Andreev band generate higher even harmonics of the Josephson ac current, and also, in the presence of inelastic scattering, a nonequilibrium dc current, which may considerably exceed the dc quasiparticle current given by the tunnel model. The distribution of travelling quasiparticles also deviates from the equilibrium due to the spectrum oscillations, which results in an additional contribution to the dc current, proportional to √ V .

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Section: Model and Basic Equationsmentioning

confidence: 99%

Nonequilibrium effects in tunnel Josephson junctions

et al. 2005

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“…These equations have been solved under certain simplifying assumptions, such as low interface NS interface transparency, 18 or in the limit of voltages small compared to E T h /e. 19 Unfortunately, these assumptions do not apply to our samples. Consequently, in the discussion below, we have chosen to discuss our results phenomenologically in the framework of RSJ model discussed above, but with the energy potential landscape being calculated using the quasiclassical theory of superconductivity.…”

mentioning

confidence: 99%

Thermal fluctuations and flux-tunable barrier in proximity Josephson junctions

et al. 2011

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The effect of thermal fluctuations in Josephson junctions is usually analysed using the Ambegaokar-Halperin (AH) theory in the context of thermal activation. "Enhanced" fluctuations, demonstrated by broadening of current-voltage characteristics, have previously been found for proximity Josephson junctions. Here we report measurements of micron-scale normal metal loops contacted with thin superconducting electrodes, where the unconventional loop geometry enables tuning of the junction barrier with applied flux; for some geometries, the barrier can be effectively eliminated. Stronger fluctuations are observed when the flux threading the normal metal loop is near an odd half-integer flux quantum, and for devices with thinner superconducting electrodes. These findings suggest that the activation barrier, which is the Josephson coupling energy of the proximity junction, is different from that of conventional Josephson junctions. Simple one dimensional quasiclassical theory can predict the interference effect due to the loop structure, but the exact magnitude of the coupling energy cannot be computed without taking into account the details of the sample dimensions. In this way, the physics of this system is similar to the phase slipping process in thin superconducting wires. Besides shedding light on thermal fluctuations in proximity junctions, the findings here also demonstrate a new type of superconducting interference device with two normal branches sharing the same SN interface on both sides of the device, which has technical advantages for making symmetrical interference devices.

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“…The relaxation role is obvious: it brings the distribution function closer to the equilibrium one, which is illustrated by solid curves in Figure 5. We would like to mention that the "subgap nonequilibrium" studied in this section is closely related to the "injection nonequilibrium" in the double-barrier junctions studied in [37,38,39,40].…”

Section: Nonequilibrium and Inelastic Relaxation Inside The Gapmentioning

confidence: 94%

Nonequilibrium and relaxation effects in tunnel superconducting junctions

Bezuglyĭ

Vasenko

Bratus

2016

Supercond. Sci. Technol.

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Abstract. The specific property of a planar tunnel junction with thin-film diffusive plates and long enough leads is an essential enhancement of its transmission coefficient compared to the bare transparency of the tunnel barrier [1,2]. In voltage-biased junctions, this creates favourable conditions for strong nonequilibrium of quasiparticles in the junction plates and leads, produced by multiparticle tunneling. We study theoretically the interplay between the nonequilibrium and relaxation processes in such junctions and found that nonequilibrium in the leads noticeably modifies the currentvoltage characteristic at eV > 2∆, especially the excess current, whereas strong diffusive relaxation restores the result of the classical tunnel model. At eV ≤ 2∆, the diffusive relaxation decreases the peaks of the multiparticle currents. The inelastic relaxation in the junction plates essentially suppresses the n-particle currents (n > 2) by the factor n for odd and n/2 for even n. The results may be important for the problem of decoherence in Josephson-junction based superconducting qubits.

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Microscopic nonequilibrium theory of double-barrier Josephson junctions

Cited by 53 publications

References 52 publications

Nonequilibrium effects in tunnel Josephson junctions

Nonequilibrium effects in tunnel Josephson junctions

Thermal fluctuations and flux-tunable barrier in proximity Josephson junctions

Nonequilibrium and relaxation effects in tunnel superconducting junctions

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