Maximally entangled mixed states and conditional entropies (4 pages)

Komal Kumar, Indranil Chakrabarty, Nirman Ganguly

Samuel R. Hedemann

Tzu-Chieh Wei, Kae Nemoto, Paul M. Goldbart +3 more

Maximally entangled mixed states are those states that, for a given mixedness, achieve the greatest possible entanglement. For two-qubit systems and for various combinations of entanglement and mixedness measures, the form of the corresponding maximally entangled mixed states is determined primarily analytically. As measures of entanglement, we consider entanglement of formation, relative entropy of entanglement, and negativity; as measures of mixedness, we consider linear and von Neumann entropies. We show that the forms of the maximally entangled mixed states can vary with the combination of (entanglement and mixedness) measures chosen. Moreover, for certain combinations, the forms of the maximally entangled mixed states can change discontinuously at a specific value of the entropy. Along the way, we determine the states that, for a given value of entropy, achieve maximal violation of Bell's inequality.

Youngrong Lim, Jaewan Kim, Soojoon Lee +1 more

Josep Amengual i Batle, M. Casas, Angel Ricardo Plastino +1 more

The maximally entangled mixed states of Munro et al. [Phys. Rev. A 64, 030302 (2001)] are shown to exhibit interesting features vis \'a vis conditional entropic measures. The same happens with the Ishizaka and Hiroshima states [Phys. Rev. A 62, 022310 (2000)], whose entanglement degree cannot be increased by acting on them with logic gates. Special types of entangled states that do not violate classical entropic inequalities are seen to exist in the space of two qubits. Special meaning can be assigned to the Munro et al. special participation ratio of 1.8.

Siping Liu

The maximally entangled mixed state in the sense of negativity for C~2C~n system is studied,and an obvious result is obtained.Moreover the relative quantum entropy of entanglement in the maximally entangled mixed state without full rank is calculated.