W-like bound entangled states and secure key distillationR. Augusiak1, 2 and P. Horodecki2, 3
1 ICFO-Institut de Ciències Fotòniques, Mediterranean Technology Park - 08860 Castelldefels (Barcelona), Spain, EU
2 Faculty of Applied Physics and Mathematics, Gdańsk University of Technology - G. Narutowicza 11/12, 80-952 Gdańsk, Poland, EU
3 National Quantum Information Centre of Gdańsk - W. Andersa 27, 81-824 Sopot, Poland, EU
received on 26 November 2008; accepted in final form by M. Lewenstein on 18 January 2009; published March 2009
published online 18 March 2009
We construct multipartite entangled states with underlying W-type structure satisfying positive partial transpose (PPT) condition under any (N- 1)|1 partition. Then we show how to distill a N-partite secure key from the states using two different methods: direct application of local filtering and novel random key distillation scheme in which we adopt the idea from recent results on entanglement distillation. Open problems and possible implications are also discussed.
03.67.Dd - Quantum cryptography and communication security.
© EPLA 2009