Method of developing analytical multipartite delocalization measures for mixed W -like states
Cathal Smyth, Gregory D. Scholes · Physical Review A · 2014
We present a method of developing analytical measures of $k\text{\ensuremath{-}}\mathrm{partite}$ delocalization in arbitrary $n\text{\ensuremath{-}}\mathrm{body}$ $W$-like states, otherwise known as mixed states in the single-excitation subspace. These measures calculate the distance of a state to its closest reference state with $k\ensuremath{-}1$ entanglement. We find that the reference state is determined by the purity of the state undergoing measurement. Measures with up to 6-body delocalization for a 6-body system are derived in full, while an algorithm for general $k\text{\ensuremath{-}}\mathrm{partite}$ measures is given.