The curious case of a cat and a quantum computer - Schrödinger’s cat in a silicon chip

Tuesday 5 July 2011

Austrian physicist Erwin Schrödinger used the famous hypothetical experiment to explain the principles of quantum mechanics in 1935. Schrödinger posed that in quantum mechanics atoms can do two things at once - being in two places or two states at the same time. The thought experiment was based on the fact that a cat is made from atoms and so he questioned whether, if put in a box with a flask of poison, a radioactive substance and a Geiger counter to detect radiation, the cat could be forced into two states at once – dead and alive.

The flask of poison would be shattered, killing the cat, if the Geiger counter detected an alpha particle spat out by the radioactive substance. The experiment can easily be set up sp there is a fifty-fifty chance that the substance produces an alpha particle. However, as the cat is sealed in a box, we cannot observe what has happened and so the science tells us the alpha particle is both emitted and not emitted, and so we assume the cat is both dead and live at the same time until we open the box.

Professor Ben Murdin and his colleagues from the Advanced Technology Institute at the University of Surrey will be using the theory to explain the concept of wave-particle duality whereby in quantum physics very small objects like electrons can sometimes behave like particles and sometimes like waves.  

When we observe waves we see effects that we don’t normally associate with moving objects, such as interference and superposition of different frequencies. The exhibit will explain how the researchers made electrons in a silicon chip behave like waves in just these kinds of ways. It will show how the group are making use of some of this quantum wave-particle weirdness to develop a new kind of powerful computer.

The team is conducting research that will allow them to create very powerful silicon chips, the building blocks of computers.  They have taken a silicon crystal with phosphorus atoms, found in standard computer chips, and used light beams to make the electrons orbiting the phosphorus perform a synchronised dance, each atom both dancing and not dancing at the same time. This is an example of the situation of Schrödinger’s famous cat, which was at once both alive and dead, but with the wonderful new twist that we can control how much “alive” and how much “dead” using the light beams (from a laser coincidentally called Felix).  They are also developing a capability to position individual phosphorus atoms precisely where we want so we can connect the dancers together, and build a quantum computer.

Visitors to the exhibition will be able to see and hear acoustical demonstrations of the wave superposition and interference of phenomena that the team were able to produce in atoms. They will also be able to operate an interactive model of an atom positioning device, and learn about engineering construction on the nanoscale - moving individual atoms on the surface of the silicon wafer is like manipulating ping-pong balls on the surface of the Sun.

The exhibition opens to the public on Tuesday 5 July 2011. Press releases on further exhibits are available.

To discuss media arrangements for the exhibition, including the suitability of exhibits for broadcast media in terms of visuals, sound and spokespeople or to arrange interviews please contact:

Nicola Kane
Press and Public Relations
The Royal Society, London
Tel: 020 7451 2508
Email: nicola.kane@royalsociety.org
Notes for editors:
About the University of Surrey
The University of Surrey is one of the UK’s leading professional, scientific and technological universities with a world class research profile and a reputation for excellence in teaching and research. Ground-breaking research at the University is bringing direct benefit to all spheres of life – helping industry to maintain its competitive edge and creating improvements in the areas of health, medicine, space science, the environment, communications, defence and social policy. Programmes in science and technology have gained widespread recognition and it also boasts flourishing programmes in dance and music, social sciences, management and languages and law. In addition to the campus on 150 hectares just outside Guildford, Surrey, the University also owns and runs the Surrey Research Park, which provides facilities for 140 companies employing 2,700 staff.
The Sunday Times names Surrey as ‘The University for Jobs' which underlines the university’s growing reputation for providing high quality, relevant degrees.
Surrey is a member of the 1994 Group of 19 leading research-intensive universities. The Group was established in 1994 to promote excellence in university research and teaching. Each member undertakes diverse and high-quality research, while ensuring excellent levels of teaching and student experience. www.1994group.ac.uk
1. Images, video and further press releases are available on the Royal Society’s advance access site for journalists, PressPortal. Please contact the press office to request a username and password.

2. General info:  The Royal Society Summer Science Exhibition showcases cutting edge research in science and engineering from across the UK. It is held annually at the Royal Society, the UK’s national academy of science. Follow the Summer Science Exhibition on Twitter at www.twitter.com/summerscience using the hashtag #SSE2011.

3. Exhibition opening times:  The Exhibition is located in the Royal Society, 6-9 Carlton House Terrace, London, SW1Y 5 AG and takes place from Tuesday 5 July to Sunday 10 July 2011. Open Tuesday 5 July 10am – 9pm, Wednesday 6 – Thursday 7 July 10am – 5pm, Friday 8 July 10am – 9pm, Saturday 9 July 10am – 6pm, Sunday 10 July 11am – 6pm.  The event is FREE and open to the public.  Further information can be found at http://royalsociety.org/summer-science/2011/.

4. The Royal Society is the UK’s national academy of science.  Founded in 1660, the Society has three roles, as a provider of independent scientific advice, as a learned Society, and as a funding agency. Our expertise is embodied in the Fellowship, which is made up of the finest scientists from the UK and beyond.  Our goals are to:

• Invest in future scientific leaders and in innovation
• Influence policymaking with the best scientific advice
• Invigorate science and mathematics education
• Increase access to the best science internationally
• Inspire an interest in the joy, wonder and excitement of scientific discovery

For further information please visit http://royalsociety.org. Follow the Royal Society on Twitter at http://twitter.com/royalsociety or on Facebook at http://www.facebook.com/theroyalsociety.

Media Enquiries

Howard Wheeler, Press Office at the University of Surrey, Tel: +44 (0)1483 686141, or Email mediarelations@surrey.ac.uk