Spin and occupation number entanglement of Dirac fields for non-inertial observers

We investigate the Unruh effect on entanglement taking into account the spin degree of freedom of the Dirac field. We analyze spin Bell states in this setting, obtaining their entanglement dependance on the acceleration of one of the partners. Then, we consider simple analogs to the occupation number entangled state |00>+|11>, but with spin quantum numbers for |11> showing that, despite their apparent similitude, while the spinless case is always qubit x qubit, for the spin case acceleration produces a qubit x qu4it state. We also introduce a procedure to consistently erase the spin information from our setting preserving occupation numbers. We show how the maximally entangled state for occupation number emerges from our setting, we also analyze its entanglement dependance on acceleration, obtaining a greater entanglement degradation than in the spinless case.