UCL Quantum Science and Technology Institute


Efficiently modelling electrons

8 July 2021

Research by UCL spin-out Phasecraft and UCL student improves the simulation of fermions on quantum computers.

An artistic rendering of how the new technique models fermions moving on a square grid. Designed by co-lead Joel Klassen.

UCL and University of Bristol spin-out Phasecraft set out a new technique for modelling fermionic particles, such as electrons. Their novel technique described in Physical Review B reduces the quantum hardware resources needed to perform these types of simulations and shows significant improvement beyond previous techniques.

Modelling large systems of fermions, such as the movement of electrons in materials, is beyond the capability of classical computers. However, quantum computing may offer the ability to model these large systems. Modelling these systems will allow for the simulation of new materials with quantum characteristics. This will prove useful for applications such as solar cells, batteries, and drug discovery.

Co-lead for the study, Phasecraft team member, and PhD candidate at UCL Charles Derby said: “Many important fields such as chemistry and materials science are concerned with the dynamics of fermion particles in physical systems - in the form of electrons. Fermions are notoriously difficult to simulate on regular computers so being able to simulate them efficiently on a quantum device would provide a faster path to tackling hard problems in areas of research such as understanding high temperature superconductivity or improving chemical reaction efficiency.”

Co-author and Phasecraft team member Joel Klassen said: “One of the most exciting potential applications for quantum computing is simulating physical systems like materials. Using new tools, like quantum computers, to develop a better understanding of how the natural world works has historically often led to dramatic technological breakthroughs. Our results reduce the resources required to perform these simulations, bringing this application closer to reality.”

The team’s compact representation of fermions outperforms all previous representations improving memory use and algorithm size each by at least 25% - a significant step towards realising practical scientific applications on near-term quantum computers

Phasecraft co-founder and research contributor Professor Toby Cubitt (UCL Computer Science and UCLQ) said: “At Phasecraft, we aim to speed up the timeline for quantum advantage. This new research continues our pioneering achievements for creating compact, resource-efficient, error-resilient software designed for the limited capacity of near-term quantum hardware. By developing these new techniques that are tuned to quantum hardware’s limitations, Phasecraft may enable potential breakthroughs in energy efficiency and storage, chemistry, and far beyond.”



An artistic rendering of how the new technique models fermions moving on a square grid. Designed by co-lead Joel Klassen. (Credit: Phasecraft).