Photonic chip is key to nurturing quantum computers

A team from Bristol’s Quantum Engineering labs has shown how to protect qubits from errors using photons in a silicon chip.

Quantum computers are gaining pace. They promise to provide exponentially more computing power for certain very tricky problems. They do this by exploiting the peculiar behaviour of quantum particles, such as photons of light.

However, quantum states of particles are very fragile. The quantum bits, or qubits, that underpin quantum computing pick up errors very easily and are damaged by the environment of the everyday world. Fortunately, we know in principle how to correct for these errors.

Quantum error correcting codes are a method to protect, or to nurture, qubits, by embedding them in a more robust entangled state of many particles. Now a team led by researchers at Bristol’s Quantum Engineering and Technology Laboratories (QETLabs) has demonstrated this using a quantum photonic chip.

The team showed how large states of entangled photons can contain individual logical qubits and protect them from the harmful effects of the classical world. The Bristol-led team included researchers from DTU in Copenhagen who fabricated the chip.

Dr Caterina Vigliar, first author on the work, said: “The chip is really versatile. It can be programmed to deliver different kinds of entangled states called graphs. Each graph protects logical quantum bits of information from different environmental effects.”

Anthony Laing, co-Director of QETLabs, and an author on the work said: “Finding ways to efficiently deliver large numbers of error protected qubits is key to one day delivering quantum computers.”

The work is published today in Nature Physics

Paper:

‘Error-protected qubits in a silicon photonic chip,’ by Vigliar, C; Laing, A et al., in Nature Physics.

Further information
The Quantum Engineering Technology Labs (QET Labs)
The QET Labs at the University of Bristol launched in April 2015 and encompass the activity of over 100 academics, staff and students. The aim is to maximise opportunities for new scientific discoveries that underpin engineering and technology development.

The QET Labs bring together the Quantum Engineering Centre for Doctoral Training (QE-CDT), the Quantum Technology Enterprise Centre (QTEC) and the research teams of their staff and students. Working together, we aim to transform science into real concept demonstrators and entrepreneurial innovation that will be the springboard for the commercial success of quantum technologies.

Bristol Quantum Information Institute
Quantum information and its translation into technologies is one of the most exciting research activities in science and technology today. Long at the forefront of the growing worldwide activity in this area, the Bristol Quantum Information Institute crystallises our research across the entire spectrum, from theory to technology. With our expert cross-disciplinary team, including founders of the field, we have expertise in all major areas of theoretical quantum information science and in experiment. We foster partnerships with the private sector and provide superb teaching and training for the future generation of quantum scientists and engineers and the prototypes of tomorrow.

Journal: Nature Physics
Method of Research: Computational simulation/modeling
Subject of Research: Not applicable
Article Title: Error-protected qubits in a silicon photonic chip
Article Publication Date: 27-Sep-2021