Decoherence-Aware Entangling and Swapping Strategy Optimization for Entanglement Routing in Quantum Networks

Quantum teleportation enables high-security communications through end-to-end quantum entangled pairs. End-to-end entangled pairs are created by using swapping processes to consume short entangled pairs and generate long pairs. However, due to environmental interference, entangled pairs decohere over time, resulting in low fidelity. Thus, generating entangled pairs at the right time is crucial. Moreover, the swapping process also causes additional fidelity loss. To this end, this paper presents a short time slot protocol, where a time slot can only accommodate a process. It has a more flexible arrangement of entangling and swapping processes than the traditional long time slot protocol. It raises a new optimization problem TETRIS for finding strategies of entangling and swapping for each request to maximize the fidelity sum of all accepted requests. To solve the TETRIS, we design two novel algorithms with different optimization techniques. Finally, the simulation results manifest that our algorithms can outperform the existing methods by up to 60 ~ 78% in general, and by 20 ~ 75% even under low entangling probabilities.