Quantum Code Design and Architectures – QCDA

General purpose quantum computers must follow a fault-tolerant design to prevent ubiquitous decoherence processes from corrupting computations. All approaches to fault-tolerance demand extra physical hardware to perform a quantum computation. Kitaev's surface, or toric, code is a popular idea that has captured the hearts and minds of many hardware developers, and has given many people hope that fault-tolerant quantum computation is a realistic prospect. Major industrial hardware developers include Google, IBM, and Intel. They are all currently working toward a fault-tolerant architecture based on the surface code. Unfortunately, however, detailed resource analysis points towards substantial hardware requirements using this approach, possibly millions of qubits for commercial applications. Therefore, improvements to fault-tolerant designs are a pressing near-future issue. This is particularly crucial since sufficient time is required for hardware developers to react and adjust course accordingly.

This consortium will initiate a European co-ordinated approach to designing a new generation of codes and protocols for fault-tolerant quantum computation. The ultimate goal is the development of high-performance architectures for quantum computers that offer significant reductions in hardware requirements; hence accelerating the transition of quantum computing from academia to industry. Key directions developed to achieve these improvements include: the economies of scale offered by large blocks of logical qubits in high-rate codes; and the exploitation of continuous-variable degrees of freedom.

The project further aims to build a European community addressing these architectural issues, so that a productive feedback cycle between theory and experiment can continue beyond the lifetime of the project itself. Practical protocols and recipes resulting from this project are anticipated to become part of the standard arsenal for building scalable quantum information processors.


The proposed project falls within the area of quantum computation and directly addresses the QuantERA target outcome “optimisation of error correction codes” and it will also develop “new architectures for quantum computation”. By advancing and improving our understanding of codes and architectures for fault-tolerant quantum computation, the project will deliver on the QuantERA expected impact to “Enhance the robustness and scalability of quantum information technologies in the presence of environmental decoherence, hence facilitating their real-world deployment.” In addition to directly benefitting experimental efforts, this will also elucidate the fundamental physical nature of fault-tolerance resources and the effects of decoherence.

The consortium will bring together partners tackling the same problems with backgrounds in physics, computer science, mathematics and (computer) engineering, and represents a truly “collaborative advanced multidisciplinary” project. While fault-tolerant quantum computation has long been a corner-stone of quantum technology science there has yet to be a co-ordinated EU network focused on this area. As such, the project will also deliver on the QuantERA expected impact to “enhance interdisciplinarity in crossing traditional boundaries between disciplines in order to enlarge the community involved in tackling these new challenges.”