Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Towards the Quantum Standard of Electric Current

13.12.2007
Researchers at Low Temperature Laboratory and Laboratory of Physics (TKK) and at University of Stony Brook (New York) have potentially solved the problem of accurately defining the ampere.

The group has developed a frequency to current converter, the accuracy of which is based on the known charge of an electron and the extreme accuracy in defining frequency. The nanodevice is essentially a single electron transistor which works as a simple single-electron turnstile. Its best performance is achieved at very low temperatures.

Previously, the electric current and its unit, the ampere, have been defined through the classical force induced to two parallel leads carrying the current. In the past years, many proposals and experiments have been put forward to achieve a relatively simple and accurate high-yield current source. No satisfying device has been implemented yet.

”The goal of our research has been to develop a reliable frequency to current converter since the frequency can be fixed with ultra high accuracy. It was interesting to observe that in this more than two decades old field, there is still room for simple inventions”, says professor Jukka Pekola, the leader of the PICO group at Low Temperature Laboratory.

In the experiments carried out at TKK in Micronova, the method was observed to work so well (see the figure) that the device can be regarded as one of the most potential candidates to realize a metrological current pump.

This device, which may revolutionize quantum metrology, works as follows: The turnstile is biased to a fixed dc voltage and its island is capacitively coupled to a sinusoidal gate voltage with frequency f. Thus the dc off-set and the amplitude of the gate drive determine exactly the number, n, of electrons passed through the device in each cycle, and hence the electric current. In this case, the current is defined to be nef, where e is the electron charge.

”At the moment, our work is focused on eliminating the remaining errors using advanced designs of the device and active error correction schemes”, tells Jukka Pekola with optimism.

The research is closely related to the so-called quantum metrological triangle experiment, in which the fundamental constants of nature e and h (Planck’s constant) are checked for consistency using the quantum standards of electric voltage, current, and resistance. These kinds of experiments are pursued in a couple of laboratories world wide, for example, at Otaniemi campus in the Center for Metrology and Accreditation in collaboration with Low Temperature Laboratory and VTT.

Professor Jukka Pekola | alfa
Further information:
http://www.micronova.fi/attachments/27MHz.EPS
http://www.nature.com/nphys/index.html
http://www.tkk.fi

More articles from Physics and Astronomy:

nachricht From rocks in Colorado, evidence of a 'chaotic solar system'
23.02.2017 | University of Wisconsin-Madison

nachricht Prediction: More gas-giants will be found orbiting Sun-like stars
22.02.2017 | Carnegie Institution for Science

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>