Konwersatorium im. J.Pniewskiego i L.Infelda
sala 0.06, ul. Pasteura 5
2023-12-18 (11:00) 
prof. dr hab. Tomasz Dietl (International Research Centre MagTop, Institute of Physics, Polish Academy of Sciences, Warsaw, Poland)
On the way to quantum ampere and quantum kilogram
In 2019, four of the seven SI base units specified in the International System of Quantities were redefined in terms of natural physical constants rather than human artifacts such as the standard kilogram. In particular, the kilogram and ampere are now defined by setting exact numerical values for the Planck constant h and the elementary electric charge e. That redefinition was prompted by the existence of the Josephson and quantum Hall effects, making us possible to connect directly quantum fundamental constants h and e to the lab practice. In the talk, I will present recent progress in fabricating resistance quantum Hall standards working in magnetic fields low enough to allow for integration with superconducting Josephson junctions that constitute the voltage standard. Such an integrated device establishes the ampere standard and the kilogram standard via the Kibble balance. I will emphasize the role of dilute magnetic semiconductors and our experimental [1] and theoretical [2] contributions to the field of quantum Hall resistance standards.
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