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Updated: May 17, 2026

Excitonic Hamiltonians for Calculating Optical Absorption Spectra and Optoelectronic Properties of Molecular Aggregates and Solids
Published on: May 27, 2020
Anisotropic excitation spectrum of a dipolar quantum Bose gas
G Bismut1, B Laburthe-Tolra, E Maréchal
1Laboratoire de Physique des Lasers, UMR 7538 CNRS, Université Paris 13, Villetaneuse, France.
Abstract:
We measure the excitation spectrum of a dipolar chromium Bose-Einstein condensate with Raman-Bragg spectroscopy. The energy spectrum depends on the orientation of the dipoles with respect to the excitation momentum, demonstrating an anisotropy that originates from the dipole-dipole interactions between the atoms. We compare our results with the Bogoliubov theory based on the local density approximation and, at large excitation wavelengths, with the numerical simulations of the time-dependent Gross-Pitaevskii equation. Our results show an anisotropy of the speed of sound.
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