Collision of impurities with Bose-Einstein condensates

Year: 2018

Authors: Lingua F., Lepori L., Minardi F., Penna V., Salasnich L.

Autors Affiliation: Politecn Torino, Dipartimento Sci Appl & Tecnol, Corso Duca Abruzzi 24, I-10129 Turin, Italy; Clark Univ, Dept Phys, Worcester, MA 01610 USA; Univ Aquila, Dipartimento Sci Fis & Chim, Via Vetoio, I-67010 Coppito, Italy; INFN, Lab Nazl Gran Sasso, Via Acitelli 22, I-67100 Assergi, Italy; CNR, INO, Via Giovanni Sansone 1, I-50019 Sesto Fiorentino, Italy; LENS European Lab Nonlinear Spect, Via Nello Carrara 1, I-50019 Sesto Fiorentino, Italy; Dipartimento Fis & Astron, Via Nello Carrara 1, I-50019 Sesto Fiorentino, Italy; Univ Padua, Dipartimento Fis & Astron Galileo Galilei, Via Marzolo 8, I-35131 Padua, Italy; Univ Padua, CNISM, Via Marzolo 8, I-35131 Padua, Italy.

Abstract: Quantum dynamics of impurities in a bath of bosons is a long-standing problem in solid-state, plasma, and atomic physics. Recent experimental and theoretical investigations with ultracold atoms have focused on this problem, studying atomic impurities immersed in an atomic Bose-Einstein condensate (BEC) and for various relative coupling strengths tuned by the Fano-Feshbach resonance technique. Here, we report extensive numerical simulations on a closely related problem: the collision between a bosonic impurity consisting of a few (41)Katoms and a BEC of Rb-87 atoms in a quasi one-dimensional configuration and under a weak harmonic axial confinement. For small values of the inter-species interaction strength (regardless of its sign), we find that the impurity, which starts from outside the BEC, simply causes the BEC cloud to oscillate back and forth, but the frequency of oscillation depends on the interaction strength. For intermediate couplings, after a few cycles of oscillation the impurity is captured by the BEC, and strongly changes its amplitude of oscillation. In the strong interaction regime, if the inter-species interaction is attractive, a local maximum (bright soliton) in the BEC density occurs where the impurity is trapped; if, instead, the inter-species interaction is repulsive, the impurity is not able to enter the BEC cloud and the reflection coefficient is close to one. However, if the initial displacement of the impurity is increased, the impurity is able to penetrate the cloud, leading to the appearance of a moving hole (dark soliton) in the BEC.

Journal/Review: NEW JOURNAL OF PHYSICS

Volume: 20      Pages from: 45001-1  to: 45001-10

More Information: We thank Giacomo Lamporesi for useful discussions. FM acknowledges funding from FP7 Cooperation STREP Project EQuaM (Grant n. 323714). LS acknowledges Project BIRD164754 of University of Padova for partial support.
KeyWords: Atoms; Bose-Einstein condensation; Bosons; Phase separation; Quantum theory; Relativity; Solitons; Statistical mechanics, Bose; Bright solitons; Dark solitons; Einstein condensate; Gross-Pitaevskii equation; Species interactions, Impurities
DOI: 10.1088/1367-2630/aab1ae

Citations: 10
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