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Practical quantum key distribution protocol without monitoring signal disturbance
Toshihiko, Sasaki
2385
Yoshihisa, Yamamoto
2386
Masato, Koashi
2387
Quantum information
Quantum cryptograph exploits the fundamental laws of quantum mechanics to provide a secure way to exchange private information. Such an exchange requires a common random bit sequence, called a key, to be shared secretly between the sender and the receiver. The basic idea behind quantum key distribution (QKD) has widely been understood as the property that any attempt to distinguish encoded quantum states causes a disturbance in the signal. As a result, implementation of a QKD protocol involves an estimation of the experimental parameters influenced by the eavesdropper’s intervention, which is achieved by randomly sampling the signal. If the estimation of many parameters with high precision is required, the portion of the signal that is sacrificed increases, thus decreasing the efficiency of the protocol. Here we propose a QKD protocol based on an entirely different principle. The sender encodes a bit sequence onto non-orthogonal quantum states and the receiver randomly dictates how a single bit should be calculated from the sequence. The eavesdropper, who is unable to learn the whole of the sequence, cannot guess the bit value correctly. An achievable rate of secure key distribution is calculated by considering complementary choices between quantum measurements of two conjugate observables. We found that a practical implementation using a laser pulse train achieves a key rate comparable to a decoy-state QKD protocol, an often-used technique for lasers. It also has a better tolerance of bit errors and of finite-sized-key effects. We anticipate that this finding will give new insight into how the probabilistic nature of quantum mechanics can be related to secure communication, and will facilitate the simple and efficient use of conventional lasers for QKD.
UTokyo Research掲載「量子暗号に30年ぶりの新原理」 URI: http://www.u-tokyo.ac.jp/ja/utokyo-research/research-news/first-breakthrough-in-quantum-cryptography-in-30-years/
UTokyo Research "First breakthrough in quantum cryptography in 30 years" URI: http://www.u-tokyo.ac.jp/en/utokyo-research/research-news/first-breakthrough-in-quantum-cryptography-in-30-years/
journal article
Nature Publishing Group
2014-05-22
application/pdf
Nature
509
475
478
AA00752384
0028-0836
1476-4687
https://repository.dl.itc.u-tokyo.ac.jp/record/669/files/nature13303_author_version.pdf
eng
info:doi/10.1038/nature13303
http://www.u-tokyo.ac.jp/ja/utokyo-research/research-news/first-breakthrough-in-quantum-cryptography-in-30-years/
http://www.u-tokyo.ac.jp/en/utokyo-research/research-news/first-breakthrough-in-quantum-cryptography-in-30-years/
http://www.nature.com/nature/journal/v509/n7501/abs/nature13303.html
Copyright (C) 2014, Rights Managed by Nature Publishing Group