Entangled states with strong positive partial transpose
Kil-Chan Ha · Physical Review A · 2010
Chru\ifmmode \acute{s}\else \'{s}\fi{}ci\ifmmode \acute{n}\else \'{n}\fi{}ski, Jurkowski, and Kossakowski [Phys. Rev. A 77, 022113 (2008)] studied quantum states with strong positive partial transpose (SPPT) and conjectured that all SPPT states are separable. We construct a two-parameter class of $3\ensuremath{\bigotimes}3$ entangled SPPT states, so the conjecture does not hold true for general SPPT states.