Polaronic Properties of an Ion in a Bose-Einstein Condensate in the Strong-Coupling Limit

Cold atoms can be used to model the Fröhlich polaron Hamiltonian using an impurity in a condensate. To probe the strong-coupling regime (which remains elusive in the solid state) charged impurities can be better suited that neutral impurities. However, the ion–atom interaction leads to a stronger de...

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Bibliographic Details
Published in:Journal of low temperature physics 2011-02, Vol.162 (3-4), p.266-273
Main Authors: Casteels, W., Tempere, J., Devreese, J. T.
Format: Article
Language:English
Subjects:
Approximation
Characterization and Evaluation of Materials
Cold atoms
Condensates
Condensed Matter Physics
Depletion
Estimates
Impurities
Joining
Magnetic Materials
Magnetism
Physics
Physics and Astronomy
Polarons
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Summary:Cold atoms can be used to model the Fröhlich polaron Hamiltonian using an impurity in a condensate. To probe the strong-coupling regime (which remains elusive in the solid state) charged impurities can be better suited that neutral impurities. However, the ion–atom interaction leads to a stronger depletion of the condensate as compared to the depletion from interaction with neutral impurities, and a good correspondence between the Fröhlich Hamiltonian and the cold atom system is only possible when the Bogoliubov approximation is valid. We use a strong-coupling variational approach to estimate an upper limit to the ion-atom coupling strength (expressed through a dimensionless coupling constant). The all-coupling path integral approach is used to estimate the values of the coupling constant that would need to be reached to probe the strong-coupling polaron physics. From these two approaches, we identify a regime where ions in condensates can model strong-coupling polarons and we calculate ground state properties in this regime.
ISSN:0022-2291
1573-7357
DOI:10.1007/s10909-010-0286-0