Emergence of atomic semifluxons in optical Josephson junctions
M. Grupp, W. P. Schleich, E. Goldobin, D. Koelle, R. Kleiner, and R. Walser
Accepted
We propose to create pairs of semifluxons starting from a flat-phase state in long, optical 0-p-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 p-junction, the detuning d of the optical transition, or the strength W0 of the laser-coupling, to induce transitions from the flat-phase state to such a semifluxon-pair state. Similarly as in superconducting 0-p-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.