title: Observation of solitonic vortices in Bose-Einstein condensates.
abstract: We observe solitonic vortices in an atomic Bose-Einstein condensate (BEC) after free expansion. Clear signatures of the nature of such defects are the twisted planar density depletion around the vortex line, observed in absorption images, and the double dislocation in the interference pattern obtained through homodyne techniques. Both methods allow us to determine the sign of the quantized circulation. Experimental observations agree with numerical simulations. These solitonic vortices are the decay product of phase defects of the BEC order parameter spontaneously created after a rapid quench across the BEC transition in a cigar-shaped harmonic trap and are shown to have a very long lifetime.
authors.affiliation: INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Povo, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: Donadello
authors.affiliation: INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Povo, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: Serafini
authors.affiliation: INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Povo, Italy.
authors.forename: Marek
authors.initials: M
authors.lastname: Tylutki
authors.affiliation: INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Povo, Italy and Kapitza Institute for Physical Problems RAS, Kosygina 2, 119334 Moscow, Russia.
authors.forename: Lev P
authors.initials: LP
authors.lastname: Pitaevskii
authors.affiliation: INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Povo, Italy.
authors.forename: Franco
authors.initials: F
authors.lastname: Dalfovo
authors.affiliation: INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Povo, Italy.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Lamporesi
authors.affiliation: INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Povo, Italy.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Ferrari