Narrow Results

We present the Gross–Pitaevskii equation for Bose–Einstein condensates (BECs) possessing the electric dipole and the electric quadrupole moments in a non-integral form. These equations are coupled with the Maxwell equations. The model under consideration includes the dipole–dipole, the dipole–quadrupole, and the quadrupole–quadrupole interactions in terms of the electric field created by the dipoles and quadrupoles. We apply this model to obtain the Bogoliubov spectrum for three-dimensional BECs with a repulsive short-range interaction. We obtain an extra term in the Bogoliubov spectrum in comparison with the dipolar BECs. We show that the quadrupole–quadrupole interaction gives a positive contribution in the Bogoliubov spectrum. Hence, this spectrum is stable.

This article summarizes recent work on the exciton-polariton BEC at Stanford, which was presented at ICAP 2008. The covered topics include cooperative cooling of exciton-polariton spin mixtures, quantum degeneracy at thermal equilibrium condition, Bogoliubov excitation spectrum, first and second order coherence, and dynamical condensation at excited Bloch bands in a one-dimensional lattice.