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Moscow University Physics Bulletin

Conditional density matrix: Entangled states in the Heisenberg representation

O. D. Timofeevskaya

Published Apr 1, 2010• 0 citations
Publisher

Abstract

The application of the conditional density matrix in the Heisenberg representation to the processes caused by entanglement allows elimination of any misunderstanding of these phenomena. We consider quantum entanglement of two- and four-particle systems, quantum correlations different from entanglement, and their causes.
DOI
10.3103/s002713491002013x

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We point out that density matrices can only be used to describe quantum states, so the entanglement contained in a density matrix is just quantum entanglement. This means a bipartite state described by a density matrix contains quantum entanglement, unless the density matrix has the form ρAB=ρA⊗ρBρ_{AB}=ρ_A\otimes ρ_BρAB​=ρA​⊗ρB​.