Regensburg 2013 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 6: Superconductivity: Tunnelling & Josephson Junctions
TT 6.6: Vortrag
Montag, 11. März 2013, 10:45–11:00, H18
ϕ Josephson junctions with a tunable current-phase relation — •Hanna Sickinger1, Adi Lipman2, Roman Mints2, Martin Weides3, Hermann Kohlstedt4, Dieter Koelle1, Reinhold Kleiner1, and Edward Goldobin1 — 1Universität Tübingen, Germany — 2Tel Aviv University, Israel — 3KIT Karlsruhe, Germany — 4Universität zu Kiel, Germany
Josephson junctions (JJs) with a ferromagnetic interlayer can be used to fabricate π JJs, which have a phase drop of π in the ground state in comparison to conventional JJs having a phase drop of 0 (0 JJs). One can use these π JJs in superconducting circuits as a device that provides a constant phase shift, i.e. as a π phase battery.
A generalization of a π JJ is a ϕ JJ, which has the phase ± ϕ in the ground state. The value of ϕ can be chosen by design and tuned in the interval 0< ϕ < π.
The ϕ JJs we used in our experiment are fabricated as 0-π JJs with asymmetric current densities in the 0 and π facets [1].
This system can be described by an effective current phase relation [1], which is tunable by an externally applied magnetic field.
We present the experimental evidence of such a ϕ JJ [2]. In particular we demonstrate that: (a) a ϕ JJ has two states −ϕ and +ϕ, (b) the unknown state can be detected (read out) by measuring Ic (Ic+ or Ic−), and (c) we can prepare a particular state by applying a magnetic field or a special bias sweep sequence.
The experimental data are in good agreement with the theoretical predictions.
[1] E. Goldobin, et al., Phys. Rev. Lett. 107, 227001 (2011)
H. Sickinger, et al., Phys. Rev. Lett. 109, 107002 (2012)