Rostock 2019 – wissenschaftliches Programm
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SYSI: Symposium Fundamental Constants and new SI
SYSI 1: Fundamental Constants and new SI
SYSI 1.3: Hauptvortrag
Mittwoch, 13. März 2019, 11:30–12:00, U Audimax
The electron charge for the definition and realisation of the ampere — •Jan-Theodoor Janssen — National Physical Laboratory, Teddington, UK
The electron charge, or more correctly the elementary charge e, was first accurately measured by Robert Millikan in his famous oil-drop experiment in 1909. With relatively simple equipment he managed to achieve a value for the elementary charge which is well within 1% of the recently fixed number for e = 1.602 176 634 × 10−19 C. This value was not determined through more accurate oil-drop type experiments but rather calculated from the fine-structure constant and the Planck constant which can both be determined more accurately. Nevertheless, fixing the elementary charge allows us to directly realise the unit ampere by counting a known number of electrons flowing through a circuit. Over the last two decades several technologies have been developed to achieve this quantised electron transport with increasing level of accuracy. High fidelity single electron current sources have several interesting applications both in metrology and quantum technology applications.