COMPASSS stands for Coherent Optical Microwave Physics for Atomic-Scale Spintronics in Silicon. It is an EPSRC Programme Grant project, aiming to completely new, single-impurity-derived devices in silicon with functions based on principles from atomic physics – namely the ability of quantum scale objects to be in two states at once.


Image: A recent image from our Nature publication demonstrating coherent control of donor impurity states.

Why are you doing this?

Next to iron and ice, silicon is the most important inorganic crystalline solid because of the tremendous ability to control electrical conduction via chemical and electrical means. The associated devices – most notably the field-effect transistor – can all be understood using only the semi-classical band theory of solids. There are currently no IT technologies that utilise the ability of electrons to be in two states at once. This ability is encountered regularly in medical physics because it is the effect that makes MRI possible. We envisage devices where “quantum information” – where electrons represent both a 1 and a 0 at the same time – can be transferred along chains of impurities in silicon, manipulated, and read out electrically. This requires control of quantum coherence in semiconductor nanostructures where many identical units can be coupled and electrically contacted.

Where are you doing this?

The project is a partnership between The Advanced Technology Institute at the University of Surrey, The London Centre for Nanotechnology at University College London, and the FELIX facility at Radboud University Nijmegen in the Netherlands.

How will this affect me?

Quantum computing has the potential to calculate much more quickly some kinds of things that would be impossible with standard computers. Because the subject is so new there have not been a great number of specific programs written, but the main example is in information security. Quantum computing will enable cracking of standard codes, but will also be able to produce uncrackable codes.

It has been suggested that quantum computers will be much better for problems where quantum physics is key, such as in medicine where the problem of molecular bonding must be solved in designing new drugs. It will also be much better for solving problems where very large amounts of information need to be manipulated, such as climate science modeling.