With limited qubit counts, connectivity and coherence times of the present quantum computers, quantum circuit optimisation is crucial for making the best use of those devices. In addition to the above algorithmic studies, this activity intends to study novel circuit optimisation protocols and error mitigation strategies to exploit at best near term quantum devices. As an example, the project Quantum Gate Pattern Recognition and Circuit Optimisation has developed an initial protocol, composed of two techniques – pattern recognition of repeated sets of gates and reduction of circuit complexity by identifying computational basis states, that demonstrates a significant gate reduction for a quantum algorithm designed to simulate parton shower processes. Another critical aspect to achieve the goals described by objective C3 is a systematic approach to benchmarking algorithms, platforms and in the future full-stack quantum systems.

This is particularly important given the increasing number of quantum hardware systems and simulators that exist today. They are provided in a variety of open-source, commercial, cloud or on-premises installation mechanisms. The different implementations exploit technologies or architectures that make different algorithms and applications more or less performant, more or less suitable. In this context, the project Automated Benchmarking and Assessment of QUantum Software (ABAQUS) is intended to design and implement an automated algorithm benchmarking system based on a public database of algorithms, configurations, and platforms. The possibility of sharing such information across a broad community of researchers and creating a “crowd-sourced” collaborative platform would ensure a rapid evolution of computer science and technology.

With the project Distributed Quantum Computing Platform, CERN aims at implementing the key aspects outlined by objective C3, namely building a distributed platform of quantum computing simulators and hardware in open collaboration with academic institutes, resources and technology providers; facilitating access to these resources for the CERN and HEP community; contributing to defining and implementing the layers of future full-stack quantum computing services.