Quantum routing of information using chiral quantum walks

TL;DR

This paper demonstrates how chiral quantum walks on minimal graphs can be used to achieve nearly perfect, robust routing of both classical and quantum information, with tunable phases enabling universal quantum routing.

Contribution

It introduces a method for quantum routing using phase-tuned chiral quantum walks on minimal graphs, enabling high-fidelity and universal information transfer.

Findings

Classical information can be routed with nearly unit fidelity by tuning a single phase.

Quantum superpositions can also be routed with high fidelity using the same scheme.

The routing probability is robust against phase fluctuations.

Abstract

We address routing of classical and quantum information over quantum network, and show how to exploit chirality to achieve nearly optimal and robust transport. In particular, we prove how continuous time chiral quantum walks over a minimal graph may be used to model directional transfer and routing of information over a network. At first, we show how classical information, encoded onto an excitation localized at one vertex of a simple graph, may be sent to any other chosen location with nearly unit fidelity by tuning a single phase. Then, we prove that high-fidelity transport is also possible for coherent superpositions of states, i.e. for routing of quantum information. Furthermore, we show that by tuning the phase parameter one obtains universal quantum routing, i.e. indipendent on the input state. In our scheme, chirality is governed by a single phase, and the routing probability is robust against fluctuations of this parameter. Finally, we address characterization of quantum routers and show how to exploit the self energies of the graph to achieve high precision in estimating the phase parameter.