2011/12/18 by Wojciech Ganczarek, Marek Kuś, Karol Życzkowski · 1 citation
Physics and Astronomy · Mathematics · #quant-ph #math-ph #math.MP
paper · pdf · doi:10.1103/physreva.85.032314
published as Phys. Rev. A 85, 032314 (2012) · 11 pages, 13 figures
arxiv created 2011/12/18 · arxiv updated 2012/03/30
Majorana representation of quantum states by a constellation of n 'stars' (points on the sphere) can be used to describe any pure state of a simple system of dimension n+1 or a permutation symmetric pure state of a composite system consisting of n qubits. We analyze the variance of the distribution of the stars, which can serve as a measure of the degree of non-coherence for simple systems, or an entanglement measure for composed systems. Dynamics of the Majorana points induced by a unitary dynamics of the pure state is investigated.