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How Can Quantum Dots Keep Your Credit Card Secure?

How Can Quantum Dots Keep Your Credit Card Secure?

A GW4 research community is working to develop quantum communication for business and personal use, such as credit card encryption, and has attracted industry interest.

Quantum technology is a growing area of research that underpins a variety of industries, from medical imaging to precision printing. One of the most significant developments in quantum technology is its application in secure communications.

Quantum technology can perhaps be summarised as a way to try out “all the answers of a calculation at the same time”, explains GW4 community lead, Dr Ruth Oulton, Senior Lecturer at University of Bristol’s Department of Electrical & Electronic Engineering and School of Physics . Where classical computing works on the principle of polarisation – 1s or 0s – quantum technology enables many single particles to interact in parallel. A perennially difficult task for a classic computer (such as identifying a prime number) can be achieved much more quickly and efficiently through quantum technology.

A GW4 research community is exploring quantum technology as a means to send secure information – an application which has attracted interest from government, military and banking sectors, but could also arrive in your pocket in the not-so-distant future.


Quantum technology works at the single particle level, and therefore requires a device that produces only a single photon at a time. The GW4-funded South West Technologies Group (SWQT) is addressing this challenge by using Quantum Dots, very small semiconductor particles, in a process called quantum key distribution. This guarantees completely secure communication through the interaction of two single particles which share a single secure and unique key.

At the moment this technology is cumbersome and expensive, often requiring huge processors that only laboratories can house. Unsurprisingly, quantum communication is currently only available to large organisations with the resources to support its application, such as the government and the banking sector.

However if the work of SWQT is successful, quantum communication may soon become mainstream. Dr Ruth Oulton says: “Lasers are used by all of us every day in devices such as CD and DVD players. However this technology once relied upon huge equipment and millions of pounds to operate. The same is true of quantum key distribution – if we can shrink this process down using semiconductors, it can become much more accessible. We hope that one day every credit card will work on quantum key distribution, bringing this cutting-edge technology to your wallet.”


This sort of technological breakthrough requires a marriage of knowledge, skills and facilities. Dr Ruth Oulton explains: “We all brought specialist expertise to the table, which has enabled us to tackle a challenge which would not have been possible for a single university. At my institution, University of Bristol, we supply semiconductor research, University of Exeter offers theory of mini quantum puzzles, University of Bath develops the fibres which enable this technology and Cardiff University’s Institute of Compound Semiconductors can turn this technology into a product.”

Semiconductor and microelectronics expertise were recently identified as specialist research and industry strengths of the region in the South West England and South East Wales Science and Innovation Audit.


GW4 funding has provided a robust framework for collaboration, and the group are determined to continue work through the South West Quantum Technology network. Dr Ruth Oulton says: “There is a strong commitment within the group to carry on this work beyond our initial GW4 funding.”

The group aims to hold at least one South West Quantum Technology meet-up a year and is working on two papers for publication, as well as a major EPSRC funding bid for quantum key distribution.

University of Bath
University of Bristol
Cardiff University
University of Exeter