Debbie Leung, Ke Li, et al.
Physical Review Letters
An even stronger effect that bound entangled states can have is presented; states which are conjectured to be undistillable become distillable by adding positive partial transpose (PPT) bound entanglement. These conjectured bound entangled states are referred to as negative partial transpose (NPT) bound entangled states.
Debbie Leung, Ke Li, et al.
Physical Review Letters
Charles H. Bennett, Peter W. Shor
Science
Graeme Smith, John A. Smolin, et al.
IEEE Trans. Inf. Theory
Charles H. Bennett, David P. DiVincenzo, et al.
Physical Review A - AMO