Enhancing quantum entanglement for continuous variables by a coherent superposition of photon subtraction and addition
We investigate how the entanglement properties of a two-mode state can be improved by performing a coherent superposition operation tâ+râ† of photon subtraction and addition, proposed by Lee and Nha Phys. Rev. A 82 053812 (2010), on each mode. We show that the degree of entanglement, the Einstein-Podolsky-Rosen–type correlation, and the performance of quantum teleportation can be all enhanced for the output state when the coherent operation is applied to a two-mode squeezed state. The effects of the coherent operation are more prominent than those of the mere photon subtraction â and the addition â† particularly in the small-squeezing regime, whereas the optimal operation becomes the photon subtraction (case of r=0) in the large-squeezing regime.
Author(s): Lee, SY (Lee, Su-Yong); Ji, SW (Ji, Se-Wan); Kim, HJ (Kim, Ho-Joon); Nha, H (Nha, Hyunchul)
Source: PHYSICAL REVIEW A 84(1): Art. No. 012302 Jul 2011