Featured Research

from universities, journals, and other organizations

Switchyard For Single Electrons

Date:
February 25, 2008
Source:
Physikalisch-Technische Bundesanstalt
Summary:
Scientists have transferred very small charge "packets," comprising a well-defined number of few electrons, between metallic electrons precisely by using a single-electron pump. A single-electron transistor, being able to resolve charge variations of a single electron or less, served as a charge detector to monitor the charge movement. The successful experiment is an important milestone on the way to the setup of a new standard for capacitance.

Scientists from Physikalisch-Technische Bundesanstalt have successfully transferred very small charge "packets", comprising a well-defined number of few electrons, between metallic electrons by using a single-electron pump. A single-electron transistor, being able to resolve charge variations of a single electron or less, served as a charge detector to monitor the charge movement.

The successful experiment is an important milestone on the way to the setup of a new standard for capacitance, where a capacitor is charged by a well-known number of electrons. The corresponding voltage can be measured using a Josephson voltage standard. Tracing the capacitance to a resistance via the quantum-Hall effect finally allows the realisation of the so-called "Quantum Metrological Triangle", which establishes a link between all three electrical quantum effects. The precision aimed at in the experiment requires the demonstrated manipulation of charge on the scale of a single electron.

Task of this metrology project is the implementation of a new capacitance standard which is based on the quantization of electrical charge in units of the elementary charge e.

The basic idea of the experiment is to charge a capacitor with a well-known number of n electrons and to measure the resulting electrical voltage U. Thus, the capacitance C of the capacitor is determined by C = ne / U. Accurate "counting" of the electrons occurs with the help of a special Single-Electron Tunneling (SET) circuit, a so-called SET-pump. If the voltage U is measured by using a Josephson voltage standard (U = ifh / 2e), the capacitance C can be expressed exclusively in terms of the fundamental constants e and h, the frequency f and integer numbers (n and i). Thus, the experiment enables electrical capacitance metrology on quantum basis, as it is already usual for the electrical voltage U (using the Josephson effect) and the electrical resistance R(using the quantum Hall effect).

If the experiment is performed with a relative uncertainty of 10-7 (0.1 ppm), it opens a way to realize the "quantum metrological triangle" which is a consistency test for the three electrical quantum effects involved. The results of this experiment will impact on a future system of units which will be based on fundamental constants.


Story Source:

The above story is based on materials provided by Physikalisch-Technische Bundesanstalt. Note: Materials may be edited for content and length.


Cite This Page:

Physikalisch-Technische Bundesanstalt. "Switchyard For Single Electrons." ScienceDaily. ScienceDaily, 25 February 2008. <www.sciencedaily.com/releases/2008/02/080225103910.htm>.
Physikalisch-Technische Bundesanstalt. (2008, February 25). Switchyard For Single Electrons. ScienceDaily. Retrieved September 30, 2014 from www.sciencedaily.com/releases/2008/02/080225103910.htm
Physikalisch-Technische Bundesanstalt. "Switchyard For Single Electrons." ScienceDaily. www.sciencedaily.com/releases/2008/02/080225103910.htm (accessed September 30, 2014).

Share This



More Matter & Energy News

Tuesday, September 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Do Video Games Trump Brain Training For Cognitive Boosts?

Do Video Games Trump Brain Training For Cognitive Boosts?

Newsy (Sep. 29, 2014) More and more studies are showing positive benefits to playing video games, but the jury is still out on brain training programs. Video provided by Newsy
Powered by NewsLook.com
CERN Celebrates 60 Years of Science

CERN Celebrates 60 Years of Science

Reuters - Business Video Online (Sep. 29, 2014) CERN, the European Organisation for Nuclear Research, celebrates 60 years of bringing nations together through science. As Joanna Partridge reports from inside the famous science centre it's also planning to turn the Large Hadron Collider particle accelerator back on after an upgrade. Video provided by Reuters
Powered by NewsLook.com
This 'Invisibility Cloak' Is Simpler Than Most

This 'Invisibility Cloak' Is Simpler Than Most

Newsy (Sep. 28, 2014) Researchers from the University of Rochester have created a type of invisibility cloak with simple focal lenses. Video provided by Newsy
Powered by NewsLook.com
New Corvette Can Secretly Record Convos And Get You Arrested

New Corvette Can Secretly Record Convos And Get You Arrested

Newsy (Sep. 28, 2014) The 2015 Corvette features valet mode – which allows the owner to secretly record audio and video – but in many states that practice is illegal. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins