Dominic Horsman - Logical tools for the second quantum revolution

In this seminar I will present recent work bridging the divide between high-level logical structures and practical quantum computing devices. The UK’s quantum computing Hub, based in Oxford, is working towards a distributed ion trap architecture for quantum information processing. Advances in hardware development have presented new challenges and opportunities for developing theoretical models to make the most of their capabilities. I will talk about some of the specific issues we have found with using previous models (quantum circuits and measurement calculi), and present work towards a new framework based in the ZX calculus of observables. I will show how this description (which includes an intuitively simple diagrammatic language based on category theory) gives new ways to frame the basic operations of ion trap devices in computational terms. I will look at the challenges presented to the circuit/measurement calculus model by the demands of distributed computing, especially entanglement generation and distillation. I will show how moving to a ZX-based model can enable the incorporation of network operations and application-level protocols into a single design language. I will also talk about error correction for the NQIT device, including recent work that places the ZX calculus as the natural language of the surface code procedure of lattice surgery. I will also briefly discuss some of the broader foundational implications of this new model, especially for work on quantum causality. I will finish by outlining the next steps in developing this model. The ultimate goal is a complete logical and software toolkit to enable us to unlock the full potential of the revolutionary devices that are now being built.