Collective modes across the soliton-droplet crossover in binary Bose mixtures

Year: 2018

Authors: Cappellaro A., Macri T., Salasnich L.

Autors Affiliation: [Cappellaro, Alberto; Salasnich, Luca] Univ Padua, Dipartimento Fis & Astron Galileo Galilei, Via Marzolo 8, I-35131 Padua, Italy.
[Macri, Tommaso] Univ Fed Rio Grande do Norte, Dept Fis Teor & Expt, BR-59078970 Natal, RN, Brazil and Int Inst Phys, BR-59078970 Natal, RN, Brazil.
[Salasnich, Luca] CNR, INO, Via Nello Carrara 1, I-50019 Sesto Fiorentino, Italy.

Abstract: We study the collective modes of a binary Bose mixture across the soliton to droplet crossover in a quasione-dimensional waveguide with a beyond-mean-field equation of state and a variational Gaussian ansatz for the scalar bosonic field of the corresponding effective action. We observe a sharp difference in the collective modes in the two regimes. Within the soliton regime, modes vary smoothly upon the variation of particle number or interaction strength. On the droplet side, collective modes are inhibited by the emission of particles. This mechanism turns out to be dominant for a wide range of particle numbers and interactions. In a small window of particle number range and for intermediate interactions, we find that monopole frequency is likely to be observed. We focus on the spin-dipole modes for the case of equal intraspecies interactions and equal equilibrium particle numbers in the presence of a weak longitudinal confinement. We find that such modes might be unobservable in the real-time dynamics close to the equilibrium as their frequency is higher than the particle emission spectrum by at least one order of magnitude in the droplet phase. Our results are relevant for experiments with two-component Bose-Einstein condensates for which we provide realistic parameters.


Volume: 97 (5)      Pages from: 053623-1  to: 053623-7

KeyWords: soft-core bosons; Einstein condensate; quantum liquid; dynamics; gases
DOI: 10.1103/PhysRevA.97.053623

Citations: 35
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