Divergences in the 2-qubits' Space: Werner and thermal states

We revisit the notion of using divergences, or relative-entropies, as measures of the distance between two mixed states, with special emphasis on power-law entropies. We analyze the Csisźar and Bregmantype q-divergences with reference to i) Werner states, and ii) thermal states obtained using a one-...

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Autores principales: Plastino, Ángel Luis, Borrás, A., Casas, Montserrat, Plastino, Ángel Ricardo
Formato: Articulo
Lenguaje:Inglés
Publicado: 2009
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Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/36276
http://www.m-hikari.com/ams/ams-password-2009/ams-password21-24-2009/plastinoAMS21-24-2009.pdf
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Sumario:We revisit the notion of using divergences, or relative-entropies, as measures of the distance between two mixed states, with special emphasis on power-law entropies. We analyze the Csisźar and Bregmantype q-divergences with reference to i) Werner states, and ii) thermal states obtained using a one-dimensional Heisenberg two-spin chain with a magnetic field <i>B</i> along the <i>z</i>-axis. In both cases, we find that the q-Jensen-Shannon divergence enlarges the range of permissible powerlaw exponents, as compared to results of previous literature. It is also shown that this divergence-measure serves as a good indicator for critical phenomena in the Heisenberg model.