Quantum gate broadcasting on graphs

Abstract

Given a known or unknown phase encoded in a higher-dimensional qudit gate, it is possible to send copies of a gate that encodes the phase to multiple receivers based on a generalized quantum teleportation. We extend this quantum gate broadcast protocol to a quantum network on directed acyclic graphs in which agents can add phase gates to be distributed and pass unknown phase gates to subsequent receivers. Similarly to the Greenberger-Horne-Zeilinger state, we show that the resource state can be efficiently prepared in finite time.