Collective Excitations of Bose–Einstein Condensate in a Rydberg Atom

In this work, we investigated a Bose–Einstein condensate (BEC) inside a Rydberg atom. We first observed the system’s density profile using the Gross–Pitaevskii equation, and then we used the Bogoliubov theory to examine the collective excitation spectra. We have also extended our study by taking into account a hybrid of two BEC species. Again, for this new system, the density profile and the collective excitation are investigated in a similar manner. The results of the BEC for one species reveal that the Rydberg atom can trap the BEC and that the excitation curve moves upward with increasing Rydberg atom interaction. We have seen roton minima for two species of BEC, and the depth of the minima shifts with the Rydberg interaction.