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A subsystem-independent generalization of entanglement

Howard Barnum·Emanuel Knill·Gerardo Ortiz·Rolando Somma·Lorenza Viola
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Abstract

We introduce a generalization of entanglement based on the idea that entanglement is relative to a distinguished subspace of observables rather than a distinguished subsystem decomposition. A pure quantum state is entangled relative to such a subspace if its expectations are a proper mixture of those of other states. Many information-theoretic aspects of entanglement can be extended to the general setting, suggesting new ways of measuring and classifying entanglement in multipartite systems. By going beyond the distinguishable-subsystem framework, generalized entanglement also provides novel tools for probing quantum correlations in interacting many-body systems.

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Howard Barnum, Emanuel Knill, Gerardo Ortiz, Rolando Somma, Lorenza Viola. 2003-05-05. A subsystem-independent generalization of entanglement. https://doi.org/10.1103/physrevlett.92.107902

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