title: Nonequilibrium dynamics and superfluid ring excitations in binary Bose-Einstein condensates.
abstract: We revisit a classic study [D. S. Hall, Phys. Rev. Lett. 81, 1539 (1998)10.1103/PhysRevLett.81.1539] of interpenetrating Bose-Einstein condensates in the hyperfine states |F=1,m{f}=-1 identical with |1 and |F=2,m{f}=+1 identical with |2 of 87Rb and observe striking new nonequilibrium component separation dynamics in the form of oscillating ringlike structures. The process of component separation is not significantly damped, a finding that also contrasts sharply with earlier experimental work, allowing a clean first look at a collective excitation of a binary superfluid. We further demonstrate extraordinary quantitative agreement between theoretical and experimental results using a multicomponent mean-field model with key additional features: the inclusion of atomic losses and the careful characterization of trap potentials (at the level of a fraction of a percent).
authors.affiliation: Department of Physics, Amherst College, Amherst, MA 01002-5000, USA.
authors.forename: K M
authors.initials: KM
authors.lastname: Mertes
authors.forename: J W
authors.initials: JW
authors.lastname: Merrill
authors.forename: R
authors.initials: R
authors.lastname: Carretero-González
authors.forename: D J
authors.initials: DJ
authors.lastname: Frantzeskakis
authors.forename: P G
authors.initials: PG
authors.lastname: Kevrekidis
authors.forename: D S
authors.initials: DS
authors.lastname: Hall