Magnetic defects in an imbalanced mixture of two Bose-Einstein condensates

Year: 2018

Authors: A. Gallemm; L. P. Pitaevskii; S. Stringari; A. Recati

Autors Affiliation: Univ Trento, INO CNR BEC Ctr, I-38123 Povo, Italy; Univ Trento, Dipartimento Fis, I-38123 Povo, Italy; RAS, Kapitza Inst Phys Problems, Kosygina 2, Moscow 119334, Russia

Abstract: When the spectrum of magnetic excitations of a quantum mixture is much softer than the density spectrum, the system becomes effectively incompressible and can host magnetic defects. These are characterized by the presence of a topological defect in one of the two species and by a local modification of the density in the second one, the total density being practically unaffected. For miscible mixtures interacting with equal intraspecies coupling constants the width of these magnetic defects is fixed by the difference between the intraspecies and interspecies coupling constants and becomes larger and larger as one approaches the demixing transition. When the density of the filling component decreases, the incompressibility condition breaks down and we predict the existence of a critical filling, below which all the atoms of the minority component remain bound in the core of the topological defect. Applications to the sodium case both in uniform and harmonically trapped configurations are considered and a protocol to produce experimentally these defects is discussed. The case of binary mixtures interacting with unequal intraspecies forces and experiencing buoyancy is also addressed.


Volume: 97 (6)      Pages from: 063615  to: 2-s2.0-85048887827

More Information: This project has received funding from the European Union´s Horizon 2020 research and innovation program under Grant Agreement No. 641122 “QUIC” and the Istituto Nazionale di Fisica Nucleare. We would also like to acknowledge enlightening discussions with A. Fetter and the members of the BEC Center. We are also indebted to M. Pi for his ideas on numerically solving the problem in a homogeneous system.
DOI: 10.1103/PhysRevA.97.063615