Entanglement improvement of pair coherent state via catalytic quantum scissors

Abstract A class of finite-dimensional quantum entanglement states is generated by applying a catalytic quantum scissors device (QSD) to one mode of the pair coherent state (PCS), which is just a superposition of | 0 , q ⟩ , | 1 , 1 + q ⟩ and | 2 , 2 + q ⟩ , with q being the photon number difference between the two modes of the PCS. The enhancement of entanglement is numerically examined in terms of the von Neumann entropy and linear entropy, depending on the parameters of the catalytic QSD and PCS. The results show that the entanglement of the truncated PCS is stronger than that of the PCS within a certain region of the parameters. In addition, the performance of the fidelity of the standard Braunstein–Kimble protocol is investigated to teleport a coherent state by using the truncated PCS as an entangled resource. Comparing with the PCS as an entangled resource, the teleportation fidelity for the truncated PCS is improved at a small parameter | ζ | of PCS and a large transmissivity T 2 of the beam-splitter. Our work reveals that the catalytic QSD is also an efficient method to realize entanglement enhancement in quantum optics and quantum information processing.