Fast generation of spin-squeezed states in bosonic Josephson junctions

Understand

We describe methods for fast production of highly coherent-spin-squeezed many-body states in bosonic Josephson junctions (BJJs).

• We start from the known mapping of the two-site Bose-Hubbard (BH) Hamiltonian to that of a single effective particle evolving according to a Schr\"odinger-like equation in Fock space.
• Since, for repulsive interactions, the effective potential in Fock space is nearly parabolic, we extend recently derived protocols for shortcuts to adiabatic evolution in harmonic potentials to the many-body BH Hamiltonian.
• The best scaling of the squeezing parameter for large number of atoms N is \xi^2_S ~ 1/N.