Experimental Observation of Ferrodark Solitons in 1D and 2D spinor BEC experiments*

Spinor BEC experiments have proven themselves as excellent quantum simulators of classical turbulent dynamics, owing to their rich spin symmetry, quantum phases and experimental control. A hot topic in this field is the observation and characterization of topological defects such as quantum vortices and solitons which are analogous to swirls, eddys and rogue waves in classical dynamics. However, these excitations persist for long times within the Spinor BEC due to defects or kinks of the quantum wavefunction.

The polar core vortex (PCV) is an example of a unique defect occurring in a transversely magnetized, ferromagnetic sBEC. PCVs exhibit opposing spin circulation in the 𝑚𝐹 = ±1

components and an unmagnetized vortex core populated by atoms in the 𝑚𝐹 = 0 state. The resulting defect is a topologically protected winding of the transverse magnetization and a flat density profile [4]. These features result in a defect that is a dissipation-free carrier of spin information with controllable dynamics, local state manipulation and read-out which will provide a testbed for ultracold spintronic devices with applications in novel magnetic memories and spin transport. The first experimental observation of a PCV was achieved by Sadler et al [3] in 2006, where the vortex sporadically formed following a magnetic field quench. Due to the non-deterministic nature of creating PCVs, further experimental study of their properties and dynamics has been limited, thus leaving a wide range of PCV applications left to be explored. In this presentation, I report on realising the first on-demand creation of PCVs in a uniform 2D 𝑅𝑏87 sBEC using tailored optical potentials and phase imprinting. We also demonstrate fine experimental control of density and transverse magnetization profiles in the condensate via the use of DMDs [1]. This capability directs our investigations into tests of ultracold spintronic devices, PCV stability, dynamics, and PCV-driven turbulence