Noiseless linear amplification for the single-photon entanglement of arbitrary polarization–time-bin qudit**Project supported by the National Natural Science Foundation of China (Grant Nos. 11474168 and 11747161), the Priority Academic Program Development of Jiangsu Higher Education Institutions, China, and the China Postdoctoral Science Foundation (Grant No. 2018M642293).

Abstract

Single-photon entanglement (SPE) is an important source in quantum communication. In this paper, we put forward a single-photon-assisted noiseless linear amplification protocol to protect the SPE of an arbitrary polarization–time-bin qudit from the photon transmission loss caused by the practical channel noise. After the amplification, the fidelity of the SPE can be effectively increased. Meanwhile, the encoded polarization–time-bin features of the qudit can be well preserved. The protocol can be realized under the current experimental conditions. Moreover, the amplification protocol can be extended to resist complete photon loss and partial photon loss during the photon transmission. After the amplification, we can not only increase the fidelity of the target state, but also solve the decoherence problem simultaneously. Based on the above features, our amplification protocol may be useful in future quantum communication.