Berlin 2008 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 15: Superconductivity: Poster Session
TT 15.37: Poster
Tuesday, February 26, 2008, 14:00–18:00, Poster B
SQUID readout of the magnetic flux states of fractional Josephson vortices. — •Andreas Dewes, Dieter Kölle, Reinhold Kleiner, and Edward Goldobin — Physikalisches Institut-Experimentalphysik II and Center for Collective Quantum Phenomena, Universität Tübingen
We present an experimental study of a direct SQUID readout of the various states of a fractional vortex molecule in a long 0-κ-0 or 0-κ-2κ Josephson junction[1]. The fractional vortices appear at the discontinuities of the Josephson phase that are created by using tiny pairs of current injectors[2,3]. The magnetic field of each vortex is coupled to an integrated DC SQUID placed in front of it. In experiment, we measure the magnetic flux Φ in the SQUID loop as a function of the bias current of the junction I, of the injector current Iinj and of the magnetic field H. By changing the bias current of the junction or by modifying the discontinuity κ∝ Iinj we can induce and observe transitions between all four states of the fractional vortex molecule (↑↑, ↓↑, ↑↓ and ↓↓). The readout system is intended to be part of a prospective fractional vortex qubit[4].
[1] E. Goldobin et. al., Phys. Rev. B 70, 174519 (2004).
[2] B. A. Malomed et. al., Phys. Rev. B 69, 064502 (2004).
[3] E. Goldobin et. al., Phys. Rev. Lett. 92, 057005 (2004).
[4] E. Golodbin et. al., Phys. Rev. B 72, 054527 (2005).