Relativity of pure states entanglement. (Q1597380)

Entanglement is a salient feature of quantum phenomena, and is regarded as an important source of computational power of quantum computers. All kinds of quantifications of entanglement are proposed. In the article under review, the authors analyze various measures of entanglement from the generalized entropies of the vector of Schmidt coefficients. For a pure state of \(N\times N,\) \(N\geq 3\) different orderings of pure states arise from the measures of entanglement used. In analogy to special relativity the set of pure states equivalent under local unitaries has a causal structure so that at each point the set splits into the future, the past, and the set of incomparable states.