Fluctuation assisted collapses of Bose–Einstein condensates

Abstract

We study the collapse dynamics of a Bose–Einstein condensate subjected to a sudden change of the scattering length to a negative value by adopting the self-consistent Gaussian state theory for mixed states. Compared to the Gross–Pitaevskii and the Hartree–Fock–Bogoliubov approaches, both fluctuations and three-body loss are properly treated in our theory. We find a new type of collapse assisted by fluctuations that amplify the attractive interaction between atoms. Moreover, the calculation of the fluctuated atoms, the entropy, and the second-order correlation function showed that the collapsed gas significantly deviated from a pure state.