Sudden death of entanglement in fermionic systems under collective decoherence

Abstract

We analyze the dynamics of entanglement due to decoherence in asystem of two identical fermions with spin 3/2 interacting with a global bosonicenvironment. We make use of an appropriate measure of the so-called fermionicentanglement to quantify the fermionic correlations, and compare the dynamicaleffects due to decoherence with those that arise in a pair of distinguishablequbits immersed in the same environment. According to the system?s initialstate, three types of qualitatively different dynamics are identified: i) invariantregime, corresponding to initial states that belong to a decoherence free subspace(DFS), which maintain invariant their entanglement and coherence throughoutthe evolution; ii) exponential decay, corresponding to initial states orthogonal tothe DFS, and evolve towards states whose entanglement and coherence decreaseexponentially; iii) entanglement sudden death, corresponding to initial states that havesome overlap with the DFS and exhibit a richer dynamics leading, in particular,to the sudden death of the fermionic entanglement, while the coherence decaysexponentially. Our analysis offers insights into the dynamics of entanglementin open systems of identical particles and into the existence of decoherence freesubspaces and entanglement sudden death in indistinguishable-fermion systems.