Efficient three-to-one entanglement purification protocol

We present a new entanglement purification protocol on three copies of a state via two bilateral controlled-NOT operations. We show that one-round successful probability of our protocol is twice as large as that of the protocol by Feng et al. [Phys. Lett. A 271 (2000) 44], [8], and that our method can be applied to the existing best protocol so as to improve the efficiency.

► We present a new three-to-one entanglement purification protocol.
► Its one-round successful probability is twice as large as s that of the FGX protocol.
► Our three-to-one protocol is more efficient than the BBPSSW protocol.
► The existing best protocol can be improved by an application of our protocol.