# Regensburg 2019 – wissenschaftliches Programm

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# TUT: Tutorials

## TUT 1: Next generation of SI-Units (joint session VA/TUT/TT)

### TUT 1.4: Tutorium

### Sonntag, 31. März 2019, 17:45–18:20, H2

**Counting electrons for the new ampere** — •Frank Hohls — Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig, Germany

On November 16th 2018 the General Conference for Weights and Measures, CGPM, adopted the resolution on the biggest revision of the International System of Units (SI) in its history: From May 20th on the SI system is completely determined by fixing the values of 7 constants of nature. One of these constants is the elementary charge which will have the exact value e = 1.602 176 634 * 10-19 As. For the unit of electrical current, the Ampere, this has the nice consequence, that the physics of electrical current and the definition of the ampere are rejoined: Counting or controlling the number of electrons passing a conductor in each second will be the natural realization of the ampere. This could be achieved by a single-electron transport (SET) pump that transfers exactly n electrons in each of its operation cycles, generating a quantized current I = nef when operated at a frequency f. The present state of the art of the SET based current standard with emphasis on the most advanced candidate will be reviewed, a SET pump based on dynamic semiconductor quantum dots with electrically tunable energy barriers.