Macroscopic Quantum Tunneling and Entangled States in Bose-Einstein Condensates

We use a multi-band Hubbard model to study beyond-mean-field effects in macroscopic quantum tunneling of excited states in Bose-Einstein condensates. Our goal is to determine straightforward observables such as the oscillation frequency of kink-like structures between two wells or the propagation speed of such structures on a lattice. As a preliminary step, we present some surprising new results for entangled states of N bosons in two wells.