Distillation of GHZ State from Multiple Copies of Arbitrary W-Class State

W. Dür et al. have shown that it is impossible to obtain a GHZ state from one copy of arbitrary W-class state via local operations and classical communication (LOCC) W. Dür, G. Vidal, and J.I. Cirac, Phys. Rev. A 62 (2000) 062314]. In our paper, the more general case is carefully investigated. We first show that, with a supply of two copies of arbitrary W-class state, we can always construct an explicit procedure to distill a GHZ state with a nonzero probability. Then based on this result, a simple procedure for distilling GHZ state from $n$ copies of arbitrary W-class state is presented. Finally, we briefly discuss the applications.