Entanglement-assisted noiseless linear amplification for arbitrary two-photon polarization–time-bin hyperentanglement

Hyperentanglement is a quantum system which simultaneously entangles in several degrees of freedom. It is an important resource in quantum communication field. In practical application of hyperentanglement, the photon transmission loss is a big obstacle. In the paper, we propose an entanglement-assisted noiseless linear amplification (NLA) protocol to protect the two-photon polarization–time-bin hyperentanglement. Our protocol can effectively increase the fidelity of this hyperentanglement, while preserve its polarization and time-bin features. Our NLA protocol can be realized under current experimental condition and further extended to protect the general N-photon polarization–time-bin hyperentanglement in the multi-directional transmission process. This NLA protocol may have important applications in future hyperentanglement-based quantum communication network field.