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An accessible definition of the ampere that allows confident and practical realisation in measurement and calibration laboratories throughout the world is needed that is nearer to the needs of modern micro- and nanofabricated electronic device performance.
It is proposed that SI unit of electric current, the ampere (A), will be redefined in terms of a fundamental physical constant in 2018, replacing the present definition based on an ideal electrodynamic experiment. This will remove the ampere dependency on the definitions of the kilogram, the metre and the second.
The redefinition will fix the numerical value of a fundamental physical constant, the elementary charge e (expressed in coulomb) and a new practical realisation will be introduced based on counting the number of electrons passing through a conductor's cross section in a given unit of time.
The key challenges of this practical realisation are a) to reliably count single electrons flowing through the device at a sufficiently high rate, and b) to scale the generated current (in the 100 pA range) to larger magnitudes, of interest for calibration.
EMRP project Quantum ampere: realisation of the new SI ampere has enabled improvements to the single electron pumps required for experimentally realising the redefined ampere.