Self-consistent field theory of polarised Bose-Einstein condensates: dispersion of collective excitationsстатья
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Дата последнего поиска статьи во внешних источниках: 6 февраля 2014 г.
Аннотация:We suggest the construction of a set of quantum hydrodynamic equations for Bose-Einstein
condensates (BECs), where the atoms have an electric dipole moment. The contribution of dipole-dipole
interactions (DDIs) to the Euler equation is obtained. Quantum equations for the evolution of a medium
polarisation are derived. A developed mathematical method allows us to study the effect of interactions on
the evolution of the polarisation. The developed method can be applied to various physical systems in which
dynamics are affected by DDIs. The derivation of the Gross-Pitaevskii equation for polarised particles from
quantum hydrodynamics is described. We show that the Gross-Pitaevskii equation applies when all the
dipoles have the same orientation which does not change with time. A comparison of the equation for
the electric dipole evolution with the equation for the magnetisation evolution is described. Dispersion of
collective excitations in the dipolar BEC, either under the influence or not under the influence of an uniform
external electric field, is considered using our method. We show that the evolution of the polarisation of
the BEC leads to the formation of a novel type of collective excitations. A detailed description of the
dispersion of the collective excitations is presented. We also consider the process of wave generation in the
polarised BEC by means of a monoenergetic beam of neutral polarised particles. We compute possibilities
for the generation of Bogoliubov and polarisation modes by the dipole beam.