Gaussian time dependent variational principle for the Bose-Hubbard model

Understand

We systematically extend Bogoliubov theory beyond the mean field approximation of the Bose-Hubbard model in the superfluid phase.

• Our approach is based on the time dependent variational principle applied to the family of all Gaussian states (i.e.
• Gaussian TDVP).
• First, we find the best ground state approximation within our variational class using imaginary time evolution in 1d, 2d and 3d.