Generalized measures of quantum correlations for mixed states |
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Authors: | R Rossignoli N Canosa L Ciliberti |
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Institution: | 1.Departamento de Física - IFLP,Universidad Nacional de La Plata,Buenos Aires,Argentina;2.Comisión de Investigaciones Científicas (CIC),Buenos Aires,Argentina;3.Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET),Buenos Aires,Argentina |
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Abstract: | The exponential speedup achieved in certain quantum algorithms based on mixed states with negligible entanglement has renewed
the interest on alternative measures of quantum correlations. Here we discuss a general measure of quantum correlations for
composite systems based on generalized entropic functions, defined as the minimum information loss due to a local measurement.
For pure states, the present measure becomes an entanglement entropy, i.e., it reduces to the generalized entropy of the reduced
state. However, for mixed states it can be nonzero in separable states, vanishing just for states diagonal in a general product
basis, like the quantum discord. Quadratic measures of quantum correlations can be derived as particular cases of the present
formalism. The minimum information loss due to a joint local measurement is also considered. The evaluation of these measures
in a simple yet relevant case is also discussed. |
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