Existence of Shapiro Steps in the Dissipative Regime in Superconducting Weak Links

Shelly, Connor; See, P.; Rungger, Ivan; Williams, Jonathan M. J.

doi:10.1103/physrevapplied.13.024070

Cited by 14 publications

(8 citation statements)

References 44 publications

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“…The observation of suppressed odd Shapiro steps does not necessarily imply the presence of a Majorana mode. The lowest Shapiro steps can be suppressed at low RF power in underdamped junctions [12], as well as in overdamped junctions with substantial self-heating [45,46]. The small capacitance and lack of hysteresis in our junctions is not consistent with these effects; furthermore, these effects cannot suppress the third step while leaving the second step intact.…”

Section: Junctions Under Rf Irradiationmentioning

confidence: 83%

Fractional AC Josephson effect in a topological insulator proximitized by a self-formed superconductor

Rosen¹,

Trimble²,

Andersen³

et al. 2021

Preprint

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A lateral Josephson junction in which the surface of a 3D topological insulator serves as the weak link should support topologically protected excitations related to Majorana fermions. The resulting 4π-periodic current-phase relationship could be detected under high-frequency excitation by the suppression of odd Shapiro steps. Here, we demonstrate such devices through the self-formation of a Pd-Te superconducting layer from a telluride topological insulator, and observe suppressed first and third Shapiro steps. Yet many of our devices, including ones where the Pd-Te layer is bolstered by an additional Al layer, show no suppression of Shapiro steps. Though we rule out the known trivial causes of suppressed Shapiro steps in our devices, our results serve as a warning that the non-equilibrium physics of these systems must be better understood before confidently claiming the observation of Majorana states.

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Section: Junctions Under Rf Irradiationmentioning

confidence: 83%

Fractional AC Josephson effect in a topological insulator proximitized by a self-formed superconductor

Rosen¹,

Trimble²,

Andersen³

et al. 2021

Preprint

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“…In both cases, the sudden voltage jump could lead to the observation of one or more missing Shapiro steps as strikingly observed recently in ref. 40 . Such a mechanism cannot suppress the third step without affecting the second one, as a consequence, we focus the following discussion on device A1.…”

Section: Resultsmentioning

confidence: 99%

Missing Shapiro steps in topologically trivial Josephson junction on InAs quantum well

et al. 2021

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Josephson junctions hosting Majorana fermions have been predicted to exhibit a 4π periodic current phase relation. One experimental consequence of this periodicity is the disappearance of odd steps in Shapiro steps experiments. Experimentally, missing odd Shapiro steps have been observed in a number of materials systems with strong spin-orbit coupling and have been interpreted in the context of topological superconductivity. Here we report on missing odd steps in topologically trivial Josephson junctions fabricated on InAs quantum wells. We ascribe our observations to the high transparency of our junctions allowing Landau-Zener transitions. The probability of these processes is shown to be independent of the drive frequency. We analyze our results using a bi-modal transparency distribution which demonstrates that only few modes carrying 4π periodic current are sufficient to describe the disappearance of odd steps. Our findings highlight the elaborate circumstances that have to be considered in the investigation of the 4π Josephson junctions in relationship to topological superconductivity.

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“…Thus, the frequency, as well as the average velocity of the chain, are locked. There emerge Shapiro steps which one can compare with experimental results [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15].…”

Section: Discussionmentioning

confidence: 99%

“…Shapiro steps are reported in the observation of different experiments [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. We concentrate here on the emergence of such steps in calculations with the FK model with periodic boundary conditions (PBC) [16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 96%

Description of Shapiro steps on the potential energy surface of a Frenkel–Kontorova model Part I: The chain in a variable box

Quapp

Bofill

2021

Eur. Phys. J. B

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We explain the vibrations of a Frenkel–Kontorova (FK) model under Shapiro steps by the action of an external alternating force. We demonstrate Shapiro steps for a case with soft ‘springs’ between an 8-particles FK chain. Shapiro steps start with a single jump over the highest $$\hbox {SP}_4$$ SP 4 in the global valley through the PES. They finish with doubled, and again doubled oscillations. We study in this part I a traditional FK model with periodic boundary conditions.

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Existence of Shapiro Steps in the Dissipative Regime in Superconducting Weak Links

Cited by 14 publications

References 44 publications

Fractional AC Josephson effect in a topological insulator proximitized by a self-formed superconductor

Fractional AC Josephson effect in a topological insulator proximitized by a self-formed superconductor

Missing Shapiro steps in topologically trivial Josephson junction on InAs quantum well

Description of Shapiro steps on the potential energy surface of a Frenkel–Kontorova model Part I: The chain in a variable box

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