Structural Vulnerability of Quantum Networks

Quantum networks allow for the transmission of quantum information between physically separated quantum processors. They play a very important role in quantum computing and quantum communication. Previous studies show clear advantages of establishing long-distance entanglement between two nodes in a quantum network for communication. Yet, the general structural vulnerability of such quantum networks has not been studied. Here we systematically examine two key notions in graph theory: articulation points (APs) and bridges, which ensure the connectivity of a network and naturally represent potential targets of attack if one aims for immediate damage to a network. We offer an analytical framework to calculate the fraction of APs and bridges for quantum networks with arbitrary degree distribution. We find that quantum networks with swap operations have lower fractions of APs and bridges than their classical counterparts. Moreover, we find that quantum networks under low degree swap operations are substantially more robust against AP attacks than their classical counterparts. These results help us better understand the structural vulnerability of such quantum networks.