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dc.contributor.authorTylutki, Marek
dc.contributor.authorAstrakharchik, Grigori
dc.contributor.authorMalomed, Boris A.
dc.contributor.authorPetrov, D. S.
dc.contributor.otherUniversitat Politècnica de Catalunya. Departament de Física
dc.identifier.citationTylutki, M. [et al.]. Collective excitations of a one-dimensional quantum droplet. "Physical review A", 21 Maig 2020, vol. 101, núm. 5, p. 051601:1-051601:5.
dc.description.abstractWe calculate the excitation spectrum of a one-dimensional self-bound quantum droplet in a two-component bosonic mixture described by the Gross-Pitaevskii equation (GPE) with cubic and quadratic nonlinearities. The cubic term originates from the mean-field energy of the mixture proportional to the effective coupling constant dg, whereas the quadratic nonlinearity corresponds to the attractive beyond-mean-field contribution. The droplet properties are governed by a control parameter ¿¿dgN2/3, where N is the particle number. For large ¿>0, the droplet features the flat-top shape with the discrete part of its spectrum consisting of plane-wave Bogoliubov phonons propagating through the flat-density bulk and reflected by edges of the droplet. With decreasing ¿, these modes cross into the continuum, sequentially crossing the particle-emission threshold at specific critical values. A notable exception is the breathing mode, which we find to be always bound. The balance point ¿=0 provides implementation of a system governed by the GPE with an unusual quadratic nonlinearity. This case is characterized by the ratio of the breathing-mode frequency to the particle-emission threshold equal to 0.8904. As ¿ tends to -8, this ratio tends to 1 and the droplet transforms into the soliton solution of the integrable cubic GPE.
dc.rightsAttribution-NonCommercial-NoDerivs 3.0 Spain
dc.subjectÀrees temàtiques de la UPC::Física
dc.subject.lcshBose-Einstein condensation
dc.subject.otherBose-Einstein condensates
dc.subject.otherUltracold gases
dc.titleCollective excitations of a one-dimensional quantum droplet
dc.subject.lemacCondensació de Bose-Einstein
dc.contributor.groupUniversitat Politècnica de Catalunya. SIMCON - First-principles approaches to condensed matter physics: quantum effects and complexity
dc.rights.accessOpen Access
dc.description.versionPostprint (author's final draft)
local.citation.authorTylutki, M.; Astrakharchik, G.; Malomed, B.; Petrov, D.
local.citation.publicationNamePhysical review A

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