Quantum Networks Face Significant 'Hyperloss' Due to Mode Mismatch, Affecting Quantum Advantage
Researchers at Universität Hamburg have identified a critical issue in quantum networks known as 'hyperloss,' which results from a small misalignment of light beams. This phenomenon can lead to a significant loss of quantum information, with up to 30% loss relative to the initial squeezing. The study, conducted by Stephan Grebien, Julian Gurs, Roman Schnabel, and Mikhail Korobko, reveals that even a 1% mode mismatch in a two-node quantum network can convert a squeezed state into an effectively thermal state, eliminating any quantum advantage. This challenges the previous assumption that such mismatches only cause minor, incoherent loss. The research highlights that hyperloss arises from quantum-correlated mixing between light's spatial modes, but also suggests that this loss can be mitigated by tuning differential spatial-mode phases. 
