Quantum Communication Networks Enhanced by Distributed Quantum Memories
Xiangyi Meng, Nicolò Lo Piparo, Kae Nemoto, István A. Kovács
TL;DR
The paper tackles enhancing quantum communication networks by using distributed quantum memories. It develops a continuum percolation model augmented by remote distillation and quantum relay, forming an α-percolation framework with contraction and reduction graph rules that yield a history-invariant, network-wide connectivity improvement. Key contributions include proving order-independence of the merging rules, deriving a subexponential time scale for remote-distillation-based growth, and demonstrating substantial connectivity gains on real-world fiber topologies (e.g., reducing required decoherence distances from thousands of kilometers to a few hundred). The work suggests a practical path toward scalable quantum networks with feasible memory resources, by exploiting component-level memory fusion and novel routing strategies.
Abstract
Building large-scale quantum communication networks has its unique challenges. Here, we demonstrate that a network-wide synergistic usage of quantum memories distributed in a quantum communication network offers a fundamental advantage. We first map the problem of quantum communication with local usage of memories into a classical continuum percolation model. Then, we show that this mapping can be improved through a cooperation of quantum distillation and relay protocols via remote access to distributed memories. This improved mapping, which we term $α$-percolation, can be formulated in terms of graph-merging rules, analogous to the decimation rules of the renormalization group treatment of disordered quantum magnets. These rules can be performed in any order, yielding the same optimal result that is characterized by the emergence of a ``positive feedback'' mechanism and the formation of spatially disconnected ``hopping'' communication components -- both marking significant improvements beyond the traditional point-to-point consideration of quantum communication in networked structures.