[Todos] Invitacion charla muy interesante en INTI

[liliana arrachea]

*Title:*
*Units of electricity:  their realization and their role in the **New SI*


*Abstract:*
Quantum Standards allow to reproduce the key units of electricity with a
precision exceeding that of any classical method by orders of magnitude.
These effects, the Josephson and the quantum Hall effect, expose the
normally unobservable quantum nature of a solid state system in a
measurement of macroscopic observables, voltage in case of the Josephson-
and resistance in case of the quantum Hall effect. For the scheduled
revision of the SI, the availability of precise links between the
macroscopic and the quantum world has been an important trigger, even more
so as this allows to also reproduce the unit of mass, kilogram. However,
the linking quantity between electrical and mechanical units is the unit of
electrical current, ampere, which ironically is most precisely represented
only indirectly via voltage and capacitance or resistance. Single electron
transport (SET) allows the obvious and conceptually simplest representation
of a current according to the relation *I = ef*, although it does not
constitute a macroscopic quantum effect in a strict sense.

After a brief overview of the history of electrical units I will summarize
the basic physics and applications of the two macroscopic quantum effects.
The main part of the talk will highlight the recent developments in the
field of SET and will introduce the concept of error accounting as a way to
deal with the shortcomings of SET devices operated at high drive
frequencies *f.* The talk will close with an outlook on the scheduled
redefinition of the SI.


*Oraror:*

Dr. Franz J. Ahlers <franz.ahlers en ptb.de>
Head of Department
"Electrical Quantum Metrology"

PTB <http://www.ptb.de/index.html> - Braunschweig

*Lugar:* Auditorio – INTI – PTM

*Fecha:* 22 de septiembre de 2015

*Hora:* 14:00 h.
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