Emergence of atomic semifluxons in optical Josephson junctions

M. Grupp; W. P. Schleich; E. Goldobin; D. Koelle; R. Kleiner; R. Walser

doi:10.1103/PhysRevA.87.021602

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Emergence of atomic semifluxons in optical Josephson junctions

M. Grupp, W. P. Schleich, E. Goldobin, D. Koelle, R. Kleiner, R. Walser

DOI 10.1103/PhysRevA.87.021602 · Physical Review A

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Abstract

We propose to create pairs of semifluxons starting from a flat-phase state in long, optical 0-π-0 Josephson junctions formed with internal electronic states of atomic Bose-Einstein condensates. In this optical system, we can dynamically tune the length a of the π junction, the detuning δ of the optical transition, or the strength Ω0 of the laser coupling to induce transitions from the flat-phase state to such a semifluxon-pair state. Similarly as in superconducting 0-π-0 junctions, there are two, energetically degenerate semifluxon-pair states. A linear mean-field model with two internal electronic states explains this degeneracy and shows the distinct static field configuration in a phase diagram of the junction parameters. This optical system offers the possibility to dynamically create a coherent superposition of the distinct semifluxon-pair states and observe macroscopic quantum oscillation.