Observation of Massless and Massive Collective Excitations with Faraday Patterns in a Two-Component Superfluid

Abstract

We report on the experimental measurement of the dispersion relation of the density and spin collective excitation modes in an elongated two-component superfluid of ultracold bosonic atoms. Our parametric spectroscopic technique is based on the external modulation of the transverse confinement frequency, leading to the formation of density and spin Faraday waves. We show that the application of a coherent coupling between the two components reduces the phase symmetry and gives a finite mass to the spin modes.

Condensation and thermalization of an easy-plane ferromagnet in a spinor Bose gas

“…3a). Compared to two-component BECs we find an additional mode due to the increased number of degrees of freedom [46,47]. Experimentally, we probe the three different modes by applying local perturbations (see Fig.…”