Long-distance quantum communication with quantum repeaters

Efficient long-distance (≥1000 km) quantum communication remains an outstanding challenge due to fiber attenuation and operation errors accumulated over the entire communication distance. Quantum repeaters (QRs), as a promising approach, can overcome both photon loss and operation errors, and significantly speedup the communication rate. Depending on the methods used to correct the two errors, all the proposed QR schemes can be classified into three generations. In this talk, I will present the first systematic comparison of the three generations by evaluating the cost of both temporal and physical resources. The application of cat codes as a single-mode encoding scheme to one-way QRs (i.e. the third generation) will be discussed. We will show that QRs with cat codes can lead to ultra-high secure key rate per mode.