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Dresden 2011 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 46: SC: Tunneling, Josephson Junctions, SQUIDs 1

TT 46.7: Talk

Thursday, March 17, 2011, 12:15–12:30, HSZ 301

Thermal and Quantum depinning of a fractional Josephson vortex — •Edward Goldobin1, Tobias Gaber1, Kai Buckenmaier1, Uta Kienzle1, Hanna Sickinger1, Dieter Koelle1, Reinhold Kleiner1, Max Meckbach2, Christoph Kaiser2, Konstantin Il’in2, and Michael Siegel21Physikalische Institut, University of Tübingen, Auf der Morgenstelle 14, 72076 Tübingen — 2Institut für Mikro- und Nanoelektronische Systeme, University of Karlsruhe, Hertzstraße 16, 76187, Karlsruhe

We investigate the bias current induced depinning of a fractional Josephson vortex in a 0-κ Josephson junction [1], where the κ-discontinuity of the phase is induced by current injectors. At high temperatures T≳ 100  mK the depinning is governed by thermal fluctuations. By measuring a depinning current histogram and extracting the effective barrier height vs. κ, one can see the signatures of fractional vortex escape [2,3]. At low T ≲ 100 mK, the escape is dominated by quantum fluctuations and the histogram width saturates. In spite of large currents involved (bias current ∼ 1 mA, injector current ∼ 5 mA), advanced experimental techniques such as superconducting bias filters and persistent mode loops for injector currents allow us to argue that the observed histograms correspond to MQT of a fractional vortex. We also discuss the particular histogram shape in this quantum regime.

[1] E. Goldobin et al., Phys. Rev. B 70, 174519 (2004).
[2] U. Kinzle et al., Phys. Rev. B 80, 014504 (2009).
[3] K. Vogel et al., Phys. Rev. B 80, 134515 (2009).

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