Conduction electrons in the carbon monolayer known as graphene have zero effective mass. This property offers unique opportunities for fast electronics, if we can somehow learn to control the dynamics of particles which have a charge but no mass. Fresh ideas are needed for this purpose, since an electric field is incapable of stopping a massless electron (its velocity being energy independent).

Prof.dr. Beenakker and his group at the Lorentz Institute for Theoretical Physics in Leiden University have started exploring the new physics of graphene soon after the announcement two years ago of the discovery of massless electrons in this material. They have identified several promising control mechanisms, and are now ready to embark on a systematic search. Their objective is to discover ways to manipulate in a controlled manner three independent electronic degrees of freedom: charge, spin, and valley.

The charge is the primary carrier of classical information, being strongly coupled to the environment, while the spin is the primary carrier of quantum information, in view of its weak coupling to the environment. The valley degree of freedom (which defines the chirality of the massless particles) is intermediate between charge and spin with regard to the coupling to the environment, and provides some unique opportunities for control.

They have the idea that by acting on the valley rather than on the charge it would be possible to fully block the electronic current (something which an electric field by itself is incapable of). To study these effects we will need to develop new methodologies, since the established methods to model quantum transport in nanostructures are unsuitable for massless carriers.

• graphene
• quantum physics