Noiseless linear amplification of polarization-encoded quantum states with efficient quantum scissors

Polarization-encoded single-photon qubit and single-photon entanglement are important resources of quantum communication. In practical long-distance quantum communication, photon transmission loss caused by the channel noise is a big obstacle. Noiseless linear amplification (NLA) is a useful method to solve the photon transmission loss problem. In the paper, we propose two efficient NLA protocols for the polarization-encoded single-photon qubit and single-photon entanglement, respectively. Our NLA protocols can increase the fidelity of the target photon state and perfectly preserve the encoded polarization feature. Moreover, local-quadrature squeezing operation is introduced into the NLA protocols to further improve the amplification. Our NLA protocols have important application in future quantum communication field.