We show that all quantum states that do not have a positive partial transpose are distillable via channels, which preserve the positivity of the partial transpose. The question whether bound entangled states with nonpositive partial transpose exist is therefore closely related to the connection between the set of separable superoperators and positive partial transpose-preserving maps.

• Received 15 May 2001

DOI:https://doi.org/10.1103/PhysRevLett.87.257902