Freely communicating

Lin Zhou, Lin Bai

Tianqi Dou, Hongwei Liu, Jipeng Wang +8 more

Quantum communication plays an important role in quantum information science due to its unconditional security. In practical implementations, the users of each communication vary with the transmitted information, and hence not all users are required to participate in each communication round. Therefore, improving the flexibility and efficiency of the actual communication process is highly demanded. Here, we propose a theoretical quantum communication scheme that realizes secret key distribution for both the two-party quantum key distribution (QKD) and multi-party quantum secret sharing (QSS) modes. The sender, Alice, can freely select one or more users to share keys among all users, and nonactive users will not participate in the process of secret key sharing. Numerical simulations show the superiority of the proposed scheme in transmission distance and secure key rate. Consequently, the proposed scheme is valuable for secure quantum communication network scenarios.

Willy Haeberli

Ryan Wilkinson

A new device can freely and efficiently change the frequency of microwave signals, enabling communication between otherwise incompatible quantum systems.

Stephen Patrick Walborn

Deng Fu-Guo, Xihan Li, Chunyan Li +2 more

We introduce an attack scheme for eavesdropping freely the ping-pong quantum communication protocol proposed by Boström and Felbinger [ Phys. Rev. Lett. 89 , 187902 (2002)] in a noise channel. The vicious eavesdropper, Eve, intercepts and measures the travel photon transmitted between the sender and the receiver. Then she replaces the quantum signal with a multi-photon signal in the same state, and measures the returned photons with the measuring basis, with which Eve prepares the fake signal except for one photon. This attack increases neither the quantum channel losses nor the error rate in the sampling instances for eavesdropping check. It works for eavesdropping the secret message transmitted with the ping-pong protocol. Finally, we propose a way for improving the security of the ping-pong protocol.