ABSTRACT Due to distance and key‐rate limitations, current quantum key distribution (QKD) technology requires the use of trusted nodes, which, together with QKD links, form a graph referred to as a QKD network. We address the problem of securely routing (relaying) keys between trusted nodes, where some of them can be malicious. Existing solutions typically rely on centralized controllers, which simplify adaptive routing and congestion control but introduce single points of failure. Moreover, some proactive key‐relay protocols distribute keys to multiple nodes in the network; thus, compromising a single node results in the compromise of the shared keys. In this paper, we propose a decentralized, topology‐oblivious key‐relay algorithm based on random walks. Our algorithm provides information‐theoretic security (ITS) for QKD network topologies having at least one non‐malicious path between any pair of nodes (in particular, ‐vertex‐disjoint paths can tolerate malicious cartels of size ). Besides, it provides strong computational security guarantees for other topologies (even for graphs with malicious articulation points). We evaluate the proposed algorithm on the GÉANT GN4‐3N topology, which provides a realistic approximation of a multi‐state cross‐border topology for future QKD networks.ABSTRACT Due to distance and key‐rate limitations, current quantum key distribution (QKD) technology requires the use of trusted nodes, which, together with QKD links, form a graph referred to as a QKD network. We address the problem of securely routing (relaying) keys between trusted nodes, where some of them can be malicious. Existing solutions typically rely on centralized controllers, which simplify adaptive routing and congestion control but introduce single points of failure. Moreover, some proactive key‐relay protocols distribute keys to multiple nodes in the network; thus, compromising a single node results in the compromise of the shared keys. In this paper, we propose a decentralized, topology‐oblivious key‐relay algorithm based on random walks. Our algorithm provides information‐theoretic security (ITS) for QKD network topologies having at least one non‐malicious path between any pair of nodes (in particular, ‐vertex‐disjoint paths can tolerate malicious cartels of size ). Besides, it provides strong computational security guarantees for other topologies (even for graphs with malicious articulation points). We evaluate the proposed algorithm on the GÉANT GN4‐3N topology, which provides a realistic approximation of a multi‐state cross‐border topology for future QKD networks.

Advanced Quantum TechnologiesAug 1, 20260 citations

Quantum communication protocols by quantum walks with two coins

Yun Shang, Wang, Yu, Li, Meng +1 more

We introduce some new perfect state transfer and teleportation schemes by quantum walks with two coins. Encoding the transferred information in coin 1 state and alternatively using two coin operators, we can perfectly recover the information on coin 1 state at target position only by at most two times of flipping operation. Based on quantum walks with two coins either on the line or on the $N$ -circle, we can perfectly transfer any qubit state. In addition, using quantum walks with two coins either on complete graphs or regular graphs, we can first implement perfect qudit state transfer by quantum walks. Compared with existing schemes driven by one coin, more general graph structures can be used to perfectly transfer more general state. Moreover, the external control of coin operator during the transmitting process can be decreased greatly. Selecting coin 1 as the sender and coin 2 as the receiver, we also study how to realize generalized teleportation over long steps of walks by the above quantum walk models. Because quantum walks is an universal quantum computation model, our schemes may provide an universal platform for the design of quantum network and quantum computer.We introduce some new perfect state transfer and teleportation schemes by quantum walks with two coins. Encoding the transferred information in coin 1 state and alternatively using two coin operators, we can perfectly recover the information on coin 1 state at target position only by at most two times of flipping operation. Based on quantum walks with two coins either on the line or on the $N$-circle, we can perfectly transfer any qubit state. In addition, using quantum walks with two coins either on complete graphs or regular graphs, we can first implement perfect qudit state transfer by quantum walks. Compared with existing schemes driven by one coin, more general graph structures can be used to perfectly transfer more general state. Moreover, the external control of coin operator during the transmitting process can be decreased greatly. Selecting coin 1 as the sender and coin 2 as the receiver, we also study how to realize generalized teleportation over long steps of walks by the above quantum walk models. Because quantum walks is an universal quantum computation model, our schemes may provide an universal platform for the design of quantum network and quantum computer.

arXiv:1802.02400Feb 7, 20183 citations

Quantum communication protocols by quantum walks with two coins

Yun Shang, Yu Wang, Meng Li +1 more

We introduce some new perfect state transfer and generalized long-distance teleportation schemes by quantum walks with two coins. By encoding the transferred information in the coin-1 state and alternately using two coin operators, we can perfectly recover the information in the coin-1 state at the target position by at most two flipping operations. On the basis of quantum walks with two coins on either a line or an N -circle, we can perfectly transfer any qubit state. In addition, using quantum walks with two coins on regular graphs, we can first implement a perfect qudit state transfer by quantum walks. Compared with existing schemes driven by one coin, more general graph structures can be used to perfectly transfer a more general state. We also study how to realize generalized teleportation over long-distance walks by the above quantum walk models.We introduce some new perfect state transfer and generalized long-distance teleportation schemes by quantum walks with two coins. By encoding the transferred information in the coin-1 state and alternately using two coin operators, we can perfectly recover the information in the coin-1 state at the target position by at most two flipping operations. On the basis of quantum walks with two coins on either a line or an N -circle, we can perfectly transfer any qubit state. In addition, using quantum walks with two coins on regular graphs, we can first implement a perfect qudit state transfer by quantum walks. Compared with existing schemes driven by one coin, more general graph structures can be used to perfectly transfer a more general state. We also study how to realize generalized teleportation over long-distance walks by the above quantum walk models.

Europhysics Letters (EPL)Jan 10, 201951 citations

Quantum teleportation based on non-maximally entangled graph states

Yi Ding, Yuzheng Wei, Zongyi Li +1 more

Quantum Information ProcessingNov 3, 20238 citations

N

-circle, we can perfectly transfer any qubit state. In addition, using quantum walks with two coins either on complete graphs or regular graphs, we can first implement perfect qudit state transfer by quantum walks. Compared with existing schemes driven by one coin, more general graph structures can be used to perfectly transfer more general state. Moreover, the external control of coin operator during the transmitting process can be decreased greatly. Selecting coin 1 as the sender and coin 2 as the receiver, we also study how to realize generalized teleportation over long steps of walks by the above quantum walk models. Because quantum walks is an universal quantum computation model, our schemes may provide an universal platform for the design of quantum network and quantum computer.