Direct Observation of the Current-Phase Relation of an Adjustable Superconducting Point Contact

Koops, Martijn C.; Duyneveldt, G. V. van; Ouboter, R. de Bruyn

doi:10.1103/physrevlett.77.2542

Cited by 52 publications

(38 citation statements)

References 20 publications

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“…Relationships of this type in the nontopological case have been known to provide a powerful way in quantitative experimental analyses of Josephson junctions. [66][67][68][69][70] Our results allow the application of the same strategy to the topological case.…”

Section: Discussionmentioning

confidence: 66%

Signatures of time-reversal-invariant topological superconductivity in the Josephson effect

Mellars

Béri

2016

Phys. Rev. B

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For Josephson junctions based on s-wave superconductors, time-reversal symmetry is known to allow for powerful relations between the normal-state junction properties, the excitation spectrum, and the Josephson current. Here we provide analogous relations for Josephson junctions involving one-dimensional time-reversal invariant topological superconductors supporting Majorana-Kramers pairs, considering both topological-topological and s-wave-topological junctions. Working in the regime where the junction is much shorter than the superconducting coherence length, we obtain a number of analytical and numerical results that hold for arbitrary normal-state conductance and the most general forms of spin-orbit coupling. The signatures of topological superconductivity we find include the fractional AC Josephson effect, which arises in topological-topological junctions provided that the energy relaxation is sufficiently slow. We also show, for both junction types, that robust signatures of topological superconductivity arise in the DC Josephson effect in the form of switches in the Josephson current due to zero-energy crossings of Andreev levels. The junction spinorbit coupling enters the Josephson current only in the topological-topological case and in a manner determined by the switch locations, thereby allowing quantitative predictions for experiments with the normal-state conductance, the induced gaps, and the switch locations as inputs.

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Section: Discussionmentioning

confidence: 66%

Signatures of time-reversal-invariant topological superconductivity in the Josephson effect

Mellars

Béri

2016

Phys. Rev. B

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“…Strongly nonsinusoidal CPRs at low T are also predicted in the diffusive regime for nanowires with lengths L Ӷ ͑ 0 l͒ 1/2 ͑where 0 is the BCS coherence length and l the electronic mean free path͒ and small transverse sizes W Ӷ L. These models were qualitatively verified for the CPR in clean ballistic niobium point contacts. 17 Recent quantitative agreement between experiment and theory was reported for aluminum atomic contacts. 18 Likharev and Yakobson first considered the effect of an increasing weak link length on the CPR for structures in which the temperature is close to the critical temperatures of both the electrodes ͑T c ͒ and the nanobridge ͑T c Ј͒.…”

Section: Introductionmentioning

confidence: 86%

Temperature dependence measurements of the supercurrent-phase relationship in niobium nanobridges

et al. 2008

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The current-phase relationship has been measured as a function of temperature for niobium nanobridges with different widths. A deformation from Josephson-like sinusoidal characteristics at high temperatures to sawtooth shaped curves at intermediate and multivalued relationships at low temperatures was observed. Based on this, possible hysteresis in the current-voltage characteristics of niobium nanobridge superconducting quantum interference devices can be attributed to phase slippage.

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“…13 The critical Josephson current and current-voltage characteristics have been thoroughly examined in these experiments by applying current or voltage bias. [13][14][15][16] There was, however, one experiment, particularly important in the qubit context, where the flux bias has been implemented: Koops et al 17 have inserted metallic QPC in a SQUID, and evaluated the Josephson current-phase dependence by measuring the induced flux with an inductively coupled SQUID magnetometer. The measurements have been only reported for the equilibrium state.…”

Section: 81mentioning

confidence: 99%

Dynamics and phonon-induced decoherence of Andreev level qubit

et al. 2005

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We present detailed theory for Andreev level qubit, the system consisting of a highly transmissive quantum point contact embedded in a superconducting loop. The two-level Hamiltonian for Andreev levels interacting with quantum phase fluctuations is derived by using the path integral method. We also derive kinetic equation describing qubit decoherence due to interaction of the Andreev levels with acoustic phonons. The collision terms are non-linear due to fermionic nature of the Andreev states, leading to slow non-exponential relaxation and dephasing of the qubit at temperature smaller than the qubit level spacing. PACS number(s): 74.50.+r, 85.25.Dq, 74.25.Kc, 03.67.Lx

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Direct Observation of the Current-Phase Relation of an Adjustable Superconducting Point Contact

Cited by 52 publications

References 20 publications

Signatures of time-reversal-invariant topological superconductivity in the Josephson effect

Signatures of time-reversal-invariant topological superconductivity in the Josephson effect

Temperature dependence measurements of the supercurrent-phase relationship in niobium nanobridges

Dynamics and phonon-induced decoherence of Andreev level qubit

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