Quantum routers eliminate signal loss for perfect state transfers
Quantum State Routing and Perfect State Transfer on Signed Graphs under Environmental Noise
Discrete MathematicsInformation Theory
Summary
Sending quantum information across networks is tricky because measuring it can destroy the data. The authors developed a new method using special kinds of quantum walks on signed graphs that route quantum information without measurements or signal loss. Their method perfectly transfers quantum states to exact destinations without reflection or interference, even in complex network shapes. They also tested how well this routing works when the quantum system faces environmental noise that can cause errors.
What this means in practice
- •For quantum network engineers: Build quantum communication networks that route unknown quantum data perfectly without measurement-induced loss or interference.
- •For quantum error correction teams: Design routing protocols resilient against environmental noise including amplitude and phase damping for quantum communications.
Authors
Nur Mohammad Sanfui, Supriyo Dutta
Abstract
Routing unknown quantum information across distributed communication networks requires autonomous, measurement-free mechanisms to prevent wave-function collapse. Szegedy quantum walks provide a mechanism for spatial state transport. The conventional walks on unweighted graphs suffer from severe back-reflection, spatial dispersion, and channel crosstalk. In this paper, we introduce a deterministic topological quantum routing architecture based on coined Szegedy quantum walks on edge-duplicated signed graphs. By treating edge signs as localized phase shifts within a balanced coin reflection, we enforce an exact zero back-scattering condition across routing nodes. We demonstrate deterministic Perfect State Transfer (PST) with unit fidelity at exact arrival times across fundamental archetypes, including the signed dumbbell switch $D_{2m,0,2n}$ and scalable glued binary trees. Furthermore, we analyse routing performance under realistic open-system amplitude and phase damping noise channels.