Phys.org (Quantum Physics News)

Too Much Entanglement? Quantum Networks Can Suffer From 'Selfish Routing,' Study Shows

Northwestern researchers have demonstrated that in multi‑user quantum communication networks, increasing the amount of shared entanglement can paradoxically degrade overall fidelity when each pair routes selfishly. By modeling non‑cooperative routing decisions, they showed that mixed entangled states generate a quantum version of "selfish routing," analogous to traffic congestion. The effect intensifies in larger networks and can be mitigated by removing certain links, echoing the Braess paradox. These findings overturn the long‑standing belief that more entanglement always improves quantum‑internet performance.