Boats, planes and graphene?

By Hamish Johnston at the APS March Meeting in Dallas

Will graphene replace silicon as the material of choice for electronics? Many folks have been asking that question since graphene became the latest “wonder material”.

Walter de Heer of the Georgia Institute of Technology answered the question with the above slide.

Just as people and goods are moved by both ships and aeroplanes, De Heer believes that there will be a place for both materials in the future.

While many physicists are trying to develop conventional transistors that use graphene as the semiconductor – essentially replacing silicon – De Heer believes that the wonder material could be used in devices that take advantage of the fact that current is quantized in very narrow ribbons of graphene. This means that quantum interference effects at junctions between ribbons could be used to switch current on and off.

Such transistors would be fundamentally different from conventional devices and immediately made me think of quantum-computing applications. This is possible in principle, according to De Heer, but couldn’t be done at room temperature. This is because the coherence lengths of the devices would be too short – although long enough to achieve switching at junctions.

However, if the junctions were cooled down, the coherence lengths could be long enough for quantum computing. Indeed, De Heer believes that ultimately there will be a place for a material as pure as graphene in quantum computers – perhaps in devices that exploit electron spin.