Graphene is constantly revealing exciting new applications and as our understanding of the material advances rapidly, we seem able to do more and more with it
— Malcolm Connolly
The world’s first graphene single-electron pump (SEP), described in a paper in Nature Nanotechnology, provides the speed of electron flow needed to create a new standard for electrical current based on electron charge. The international system of units (SI) comprises seven base units (the metre, kilogram, second, Kelvin, ampere, mole and candela). Ideally these should be stable over time and universally reproducible. This requires definitions based on fundamental constants of nature which are the same wherever you measure them.
The present definition of the Ampere, however, is vulnerable to drift and instability. This is not sufficient to meet the accuracy needs of present and certainly future electrical measurement. The highest global measurement authority, the Conférence Générale des Poids et Mesures, has proposed that the ampere be re-defined in terms of the electron charge.
The front runner in this race to redefine the ampere is the single-electron pump (SEP). SEPs create a flow of individual electrons by shuttling them in to a quantum dot – a particle holding pen – and emitting them one at a time and at a well-defined rate. The paper published this week describes how a graphene SEP has been successfully produced and characterised for the first time, and confirms its properties are extremely well suited to this application.
Read the full story
Image: Electron pumps made from graphene work ten times faster than similar pumps made from conventional three-dimensional materials and can be used to generate larger currents
Credit: Malcolm Connolly, Cambridge
Reproduced courtesy of the University of Cambridge
_________________________________________________