Double-layer Bose-Einstein condensates: A quantum phase transition in the transverse direction, and reduction to two dimensions

Mateus C.P. Dos Santos, Boris A. Malomed, Wesley B. Cardoso*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

We revisit the problem of the reduction of the three-dimensional (3D) dynamics of Bose-Einstein condensates, under the action of strong confinement in one direction (z), to a 2D mean-field equation. We address this problem for the confining potential with a singular term, viz., Vz(z)=2z2+ζ2/z2, with constant ζ. A quantum phase transition is induced by the latter term, between the ground state (GS) of the harmonic oscillator and the 3D condensate split in two parallel noninteracting layers, which is a manifestation of the "superselection"effect. A realization of the respective physical setting is proposed, making use of resonant coupling to an optical field, with the resonance detuning modulated along z. The reduction of the full 3D Gross-Pitaevskii equation (GPE) to the 2D nonpolynomial Schrödinger equation (NPSE) is based on the factorized ansatz, with the z -dependent multiplier represented by an exact GS solution of the 1D Schrödinger equation with potential Vz(z). For both repulsive and attractive signs of the nonlinearity, the 2D NPSE produces GS and vortex states, that are virtually indistinguishable from the respective numerical solutions provided by full 3D GPE. In the case of the self-attraction, the threshold for the onset of the collapse, predicted by the 2D NPSE, is also virtually identical to its counterpart obtained from the 3D equation. In the same case, stability and instability of vortices with topological charge S=1, 2, and 3 are considered in detail. Thus, the procedure of the spatial-dimension reduction, 3D → 2D, produces very accurate results, and it may be used in other settings.

Original languageEnglish
Article number042209
JournalPhysical Review E
Volume102
Issue number4
DOIs
StatePublished - Oct 2020

Funding

FundersFunder number
INCT465469/2014-0
National Institute of Science and Technology
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Conselho Nacional de Desenvolvimento Científico e Tecnológico306065/2019-3, 425718/2018-2
Israel Science Foundation1286/17, 88887.364746/2019-00
Fundação de Amparo à Pesquisa do Estado de Goiás201710267000540, 201710267000503

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