Dresden 2006 – scientific programme
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TT: Tiefe Temperaturen
TT 7: Superconductivity & Solids At Low Temperature - Poster Session
TT 7.49: Poster
Monday, March 27, 2006, 14:00–17:45, P1
Fractional Josephson vortices as candidates for the observation of macroscopic quantum effects — •T. Gaber1, E. Goldobin1, K. Buckenmeier1, K. Vogel2, O. Crasser2, R. Walser2, W. P. Schleich2, D. Koelle1, and R. Kleiner1 — 1Physikalisches Institut, Experimentalphysik II,Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen — 2Universität Ulm, Abteilung Quantenphysik, D-89069 Ulm
It is established experimentally that in long Josephson junctions (LJJ), where the phase dynamics can be mapped to the sine-Gordon equation with phase discontinuities, fractional vortices can appear spontaneously. In contrast to fluxons which are solitons and can move freely along LJJs, fractional vortices are pinned at the discontinuities and may have positive or negative polarity. They are useful for information encoding and are similar to spin-1/2 systems. In contrast to fluxon based devices, a fractional vortex can represent the ground state of the system which makes it more robust.
Fractional vortices, fractional vortex molecules and vortex crystals are interesting systems to study macroscopic quantum effects. We discuss the quantum properties of a single fractional vortex in a 0-π LJJ and a two-fractional-vortex molecule in a 0-π-0 LJJ and give an estimation of the crossover temperature in typical experiments. Several possibilities to construct and manipulate the quantum states of one or more vortices are presented. Possible readout schemes using integer fluxons and/or RSFQ logic are discussed.