Researchers edge closer to functioning quantum computer

Quantum computer

Scientists may be one step closer to building a large scale quantum computer thanks to new findings from researchers at the University of Sheffield.

The field of quantum computing is in its infancy and researchers have yet to build a complete system that could replace current computer technology, but the theoretical principles behind it propose a new generation of more powerful and more secure computers.

While classical computers rely on electrons, the subatomic particles that carry the negative charge in electrical circuits, one approach to building a quantum computer is instead based on interactions between particles of light, known as photons.

Typically, interactions between photons are very weak. But new research by the Department of Physics and Astronomy's Low Dimensional Structures and Devices research group, and published in the journal Optica, has uncovered a possible solution.

The group's aim is to incorporate all of the components for a quantum processor within a single semiconductor chip. Experiments have been based around a tiny semiconductor structure known as a quantum dot, which is embedded into the chip. The quantum dot changes state when it interacts with a single photon. This changes the interaction between the quantum dot and a subsequent photon, creating an effective interaction between the two photons.

With their latest findings, the group has shown how these interactions can be turned on or off by using an electric field to control the state of the quantum dot. The technique is scalable, so it can be applied to multiple quantum dots, making it easier for scientists to envisage a large-scale computer that can handle complex processes.

The research was led by PhD student Dominic Hallett and Research Associate Dr Andrew Foster. Current PhD student David Hurst and former Research Associate Ben Royall are also authors on the paper, alongside Dr Pieter Kok, Professor Mark Fox, Professor Maurice Skolnick and Dr Luke Wilson in Physics and Astronomy, Dr Ed Clarke in the Department of Electronic and Electrical Engineering, and Dr Igor Itskevich at the University of Hull.