Security of a new two-way continuous-variable quantum key distribution protocol

摘要

The original two-way continuous-variable quantum-key-distribution (CV QKD)protocols [S. Pirandola, S. Mancini, S. Lloyd, and S. L. Braunstein, NaturePhysics 4, 726 (2008)] give the security against the collective attack on thecondition of the tomography of the quantum channels. We propose a family of newtwo-way CV QKD protocols and prove their security against collective entanglingcloner attacks without the tomography of the quantum channels. The simulationresult indicates that the new protocols maintain the same advantage as theoriginal two-way protocols whose tolerable excess noise surpasses that of theone-way CV-QKD protocol. We also show that all sub-protocols within the familyhave higher secret key rate and much longer transmission distance than theone-way CV-QKD protocol for the noisy channel.