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arXiv · 0809.1346

Semifluxon molecule under control

Andreas Dewes·Tobias Gaber·Dieter Koelle·Reinhold Kleiner·Edward Goldobin
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Abstract

Josephson junctions with a phase drop pi in the ground state allow to create vortices of supercurrent carrying only half of the magnetic flux quantum Phi_0~2.07*10^-15 Wb. Such semifluxons have two-fold degenerate ground states denoted up (with flux +Phi_0/2 and supercurrent circulating clockwise) and down (with flux -Phi_0/2 and supercurrent circulating counterclockwise). We investigate a molecule consisting of two coupled semifluxons in a 0-pi-0 long Josephson junction. The fluxes (polarities) of semifluxons are measured by two on-chip SQUIDs. By varying the dc bias current applied to the 0-pi-0 junction, we demonstrate controllable manipulation and switching between two states, up-down and down-up, of a semifluxon molecule. These results provide a major step towards employing semifluxons as bits or qubits for classical and quantum digital electronics.

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Andreas Dewes, Tobias Gaber, Dieter Koelle, Reinhold Kleiner, Edward Goldobin. 2008-09-08. Semifluxon molecule under control. https://doi.org/10.1103/physrevlett.101.247001

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