Resonant spin-changing collisions in spinor Fermi gases

Spin-changing collisions in trapped Fermi gases may acquire a resonant character due to the compensation of quadratic Zeeman effect and trap energy. These resonances are absent in spinor condensates and pseudo-spin-1/2 Fermi gases, being a characteristic feature of high-spin Fermi gases that allows spinor physics at large magnetic fields. We analyze these resonances in detail for the case of lattice spinor fermions, showing that they permit to selectively target a spin-changing channel while suppressing all others. These resonances allow for the controlled creation of non-trivial quantum superpositions of many-particle states with entangled spin and trap degrees of freedom, which remarkably are magnetic-field insensitive. Finally, we show that the intersite tunneling may lead to a quantum phase transition described by an effective quantum Ising model.