Thursday, March 26, 2015

Accurately measured with the Josephson quantum voltmeter voltages

The so-called Josephson effect, working voltages very precisely. In the future, help reduce uncertainties, a quantum voltmeter.

For over four years developed esz calibration and metrology together with Supracon from Jena and the PTB - Physikalisch-Technische Bundesanstalt, Braunschweig, the world's first industrial use AC / DC Josephson quantum voltmeter. Under the Josephson effect is understood a physical effect, which describes the tunnel current between two superconductors. Josephson junctions are very accurate frequency-to-voltage converter.

In the metrology of the inverse Josephson effect is used in order to accurately represent voltages. So far, only Josephson standards are used for DC representation. With the AC / DC Josephson quantum voltmeter can measure in addition to 2 kHz alternating voltages up to 7.19 V at a frequency of 10 Hz. By AC / DC Josephson quantum voltmeter should be possible to reduce by up to a factor of 1000 and AC voltages by a factor of 50 in future uncertainty in measurement of DC voltage.

"The next challenge is how we get away from liquid helium as the operating medium," says Alexander Winter Meier, applications engineer at esz. "Liquid helium is very expensive and difficult to obtain. We want to work with a small cooler which allows an operating temperature of 4 K (-269 ° C) on the chip. "This temperature is necessary to maintain the Josephson elements in the superconducting state. By realizing the next development stage esz will be able to operate the AC / DC Josephson normal cost effective and durable.

The Josephson system is currently for four weeks in the laboratory esz to make a series of functional tests and measurements in the industrial environment. After the system goes back to the further development Quantenkalibrator for current, voltage and resistance to Supracon to Jena. The Josephson Quantenkalibrator should be fully developed end of 2016. The total investment of esz for the project is 340,000 euros.

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