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

TL;DR

This paper introduces a new family of two-way continuous-variable quantum key distribution protocols that are secure against collective entangling cloner attacks without requiring quantum channel tomography, offering improved performance over one-way protocols.

Contribution

The paper presents a novel family of two-way CV QKD protocols with proven security against specific attacks without channel tomography, enhancing key rate and transmission distance.

Findings

Protocols maintain advantage over one-way CV-QKD.

Higher secret key rate in noisy channels.

Longer transmission distances achieved.

Abstract

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