Quantum Computation and Information Seminar 

23/07/2004, 15:00 — 16:00 — Room P4.35, Mathematics Building
Simon Gay, University of Glasgow

Communicating quantum processes

We define a language CQP (Communicating Quantum Processes) for modelling systems which combine quantum and classical communication and computation. CQP combines the communication primitives of the pi-calculus with primitives for measurement and transformation of quantum state; in particular, qubits can be transmitted from process to process along communication channels. CQP has a static type system which classifies channels, distinguishes between quantum and classical data, and controls the use of quantum state. We formally define the syntax, operational semantics and type system of CQP, prove that the semantics preserves typing, and prove that typing guarantees that each qubit is owned by a unique process within a system. We illustrate CQP by means of several examples, and outline our plans for formal verification of quantum communication and cryptographic systems. This work will also be presented at the Workshop on Quantum Programming Languages in Turku, Finland, 12th-13th July.