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 dependence 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 $|11⟩$. We show that, despite their apparent similitude, while the spinless case is always $\text{qubit}\times \text{qubit}$, for the spin case acceleration produces a $\text{qubit}\times \text{four-level}$ quantum system 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 as well analyze its entanglement dependence on acceleration, obtaining greater entanglement degradation than in the spinless case.

• Received 27 February 2009

DOI:https://doi.org/10.1103/PhysRevA.80.012314