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Conditional q-entropies and quantum separability: a numerical exploration

J Batle1, A R Plastino1,2, M Casas1 and A Plastino2

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We revisit the relationship between quantum separability and the sign of the relative q-entropies of composite quantum systems. The q-entropies depend on the density matrix eigenvalues pi through the quantity ωq = ∑ipqi. Rényi's and Tsallis' measures constitute particular instances of these entropies. We perform a systematic numerical survey of the space of mixed states of two-qubit systems in order to determine, as a function of the degree of mixture, and for different values of the entropic parameter q, the volume in state space occupied by those states characterized by positive values of the relative entropy. Similar calculations are performed for qubit–qutrit systems and for composite systems described by Hilbert spaces of larger dimensionality. We pay particular attention to the limit case q. Our numerical results indicate that, as the dimensionalities of both subsystems increase, typical mixed states of composite quantum systems tend, as far as their relative q-entropies are concerned, to behave in a classical way.


PACS

03.67.Lx Quantum computation architectures and implementations

03.65.-w Quantum mechanics

89.70.-a Information and communication theory

MSC

81P68 Quantum computation and quantum cryptography (See also 68Q05, 94A60)

94A17 Measures of information, entropy

Subjects

Computational physics

Statistical physics and nonlinear systems

Quantum information and quantum mechanics

Dates

Issue 48 (6 December 2002)

Received 1 August 2002, in final form 2 October 2002

Published 19 November 2002



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