Entanglement, mixedness, and q-entropies

Abstract We revisit the relationship between entanglement and purity of states of two-qubits systems, using the  q -entropies as measures of the degree of mixture. The  q -entropies depend on the density matrix eigenvalues p i through the quantity ω q =∑ i p i q . Renyi's measures constitutes particular instances of these entropies. We pay particular attention to the case q =2 and to the limit case q →∞. We provide analytical support to numerical results recently reported in the literature.

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