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Session Topic: 9C, Uncertainty Session

   

Paper Title: Do Quantum Standards Have to be Validated?

   

Date & Time: THURSDAY, August 8, 2002

 

8:30 - 10:00am PARALLEL SESSIONS - SESSION 9

   

Speaker: Bernd Schumacher PTB

Email: Bernd.Schumacher@PTB.DE

   

Since 1990 the electrical units for voltage and resistance are realized using quantum standards, the Josephson effect for voltage and the quantized Hall effect (QHE) for resistance. It was agreed to use conventional values for these effects with the great advantage of having the same realization of these units at any place in the world and at any time without the need for transporting standards and thus removing trade barriers. There is no doubt that the fundamental quantum effects are correct, but the practical application of these quantum standards is a different story. The Mutual Recognition Arrangement (MRA) requires to assure international comparability of measurement standards by key-comparisons and this includes also quantum standards. We will show examples in the field of electricity, why key-comparisons for quantum standards are necessary. Although the mentioned effects are error-free, the use of these effects can possibly lead to undetected sources of error. As an example for a key-comparison, comparing quantum standards, the organization of a key-comparison at a resistance value of 100 W, which can be directly linked to the QHE, is described. This comparison allows a great number of national metrological institutes to compare their realization of the unit of resistance within a reasonable period of time. The Physikalisch Technische Bundesanstalt (PTB) is pilot laboratory for this key-comparison. We report on the necessary preparations and possible obstacles occurring in such a comparison.

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