Interplay between coherence and entanglement in macroscopic cat states of a bosonic Josephson junction

Interplay between coherence and entanglement in macroscopic cat states of a bosonic Josephson junction

Seminar author:Giovanni Mazzarella

Event date and time:04/08/2011 12:30:pm

Event location:Sala de Graus II

Event contact:

We study the interplay between coherence and entanglement in macroscopic Schr\”odinger-cat states of a bosonic Josephson junction made of $N$ ultracold and dilute atoms confined in a quasi-one-dimensional double-well optical trap. We characterize the presence of macroscopic Schrodinger-cat states by using the Fisher information $F$, the coherence by using the visibility $\alpha$ of the interference fringes in the momentum distribution, and the entanglement of the ground-state by using the entanglement entropy $S$. Within the two-site Bose-Hubbard model framework these quantities are calculated by changing the inter-atomic interaction strength from the strongly attractive regime to the strongly repulsive one. In this way we investigate the crossover from a macroscopic Schr\”odinger-cat state across an atomic coherent state to a pure Fock state.