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Primeur weekly 2011-09-26

Special

Steve Conway to highlight European HPC market at EGI Technical Forum ...

Exascale supercomputing

Appro and SDSC Gordon supercomputer to provide up to 35 million IOPS ...

"Stampede's" comprehensive capabilities to bolster U.S. open science computational resources ...

The Cloud

Bull and CA Technologies form a strategic alliance ...

Gresham Computing to launch Clareti Transaction Control ...

HP Channel Partners open new Cloud Centers of Excellence ...

IBM expands Cloud delivery of smarter commerce ...

'Managed application services added to Interoute’s unified computing portfolio ...

Midas Medici's CIMCORP wins $3 million contract for data centre solutions in Brazil ...

Oracle successfully completes Continua Health Alliance interoperability testing ...

SDSC announces scalable, high-performance data storage Cloud ...

Desktop Grids

e-ScienceTalk Briefing on Desktop Grids has just appeared ...

BOINC integrated with Wordpress ...

OurGrid version 4.2.6 now released ...

EuroFlash

Bright Computing now resells Altair PBS Professional Workload Manager, delivering HPC operational efficiencies and cost savings ...

Repsol and BSC create a joint research centre in Spain ...

Sailing Mediterranean ICT seas - Boosting high-speed ICT infrastructures across Europe and Mediterranean ...

Mini-quantum computer passes test ...

Like fish on waves: electrons go surfing ...

USFlash

Emerson Network Power doubles the life span of VME boards ...

Retailers generate high-volume sales with IBM solution for smarter commerce ...

Nearly half of IT decision makers favour solid-state storage technology ...

University of Minnesota Supercomputing Institute adds Dell Terascala HPC Storage Solution to Itasca system ...

Oracle announces the immediate availability of the Oracle Database Appliance ...

Oracle Financial Services Revenue Management and Billing running with Oracle Exadata Database Machine delivers extreme performance ...

Major supercomputing boost for University of Canterbury ...

Post-silicon computing ...

Like fish on waves: electrons go surfing

22 Sep 2011 Bochum - Physicists at the Ruhr-University Bochum (RUB), working in collaboration with researchers from Grenoble and Tokyo, have succeeded in taking a decisive step towards the development of more powerful computers. They were able to define two little quantum dots (QDs), occupied with electrons, in a semiconductor and to select a single electron from one of them using a sound wave, and then to transport it to the neighbouring QD. A single electron "surfs" thus from one quantum dot to the next like a fish on a wave. Such manipulation of a single electron will in the future also enable the combination of considerably more complex quantum bits instead of classical bits ("0" and "1" states). The researchers have reported their results inNature, one of the highest-impact-factor international scientific journals.

Electrons can move as freely as fish in water in electric conductors (metals) and semiconductors such as silicon (Si) or gallium arsenide (GaAs), albeit not "swimming" of their own but moving owing to differences in voltage. Inside a metal, they are present as a huge number of fish that fill nearly the entire volume of water. In semiconductors, this "fish density" is not as high and so the distance between the electrons (fish) is much larger. The electrons can be concentrated in a thin layer near the surface by the application of an external voltage. The new method that the international team of researchers has developed now fulfils this "fisherman's dream" for semiconductor physicists. The electron "fish" are all in one layer close to the surface and easily, individually accessible from the surface.

Prof. Andreas Wieck, physicist at the RUB, points out that there are, however no, "big fish", all electrons being similar and even always identical, undistinguishable objects. The method that the researchers from Germany, France and Japan used, nevertheless enables the "emission" of individual electrons from the QD, moving them over a specific distance and then detecting them at the neighbouring QD. A distance of four micrometres (μm) was used in the experiment - this is twenty times larger than a highly integrated transistor.

Targeted transport of individual electrons is possible in the following way: First, a QD is defined between the tips of four electrodes to form this zero-dimensional object, containing some hundred electrons. The scientists subsequently send a sound wave along the semiconductor surface using interdigital (like two combs fitted together without touching each other) electrodes to which they apply a radio frequency voltage. This method functions in the opposite way as the electrical discharge of a piezo ignition system in which a crystal is deformed to attain a voltage. The researchers applied voltage to the crystal and thus deform it, and the alternating voltage leads to the formation of a sound wave.

In a sample, this wave moves, for example, from left to right through the quantum dot at the velocity of sound - inside the crystal at three kilometres per second. Its height is adjusted so that it extracts exactly one "fish" from it. The latter subsequently surfs on the wave in a one-dimensional channel. The "fish" arrives at the neighbouring quantum dot 4 μm to the right thereof. The researchers were able to attain good statistics by repetition of the waves and measurements and thus capable of determining the reliability of the method. During the first experiments, the probability of emission and detection of a single electron with the wave was 96 and 92%, respectively.

It is not possible to differentiate between the electrons "fish", but they can be differently aligned because they rotate like little spinning tops. This is called the "spin" of the electron. For example one can align a fish with "its head upwards", let it be transported with the wave, and then detect it again at the target quantum dot still having "its head upwards". The time for the spin to change is longer than the surfing time on the wave, so the probability of this occurring is very high. The quantum bits of the future will also consist of such spin-polarized electrons.

The researchers attained their results with samples prepared by so-called molecular beam epitaxy at the chair of Applied Solid State Physics at the Ruhr University Bochum. They were structured in Tokyo and subsequently measured in Grenoble. But not only the samples, also a further development of this concept originates from Bochum: Prof. Wieck already published his vision of an electron directional coupler with two parallel one-dimensional channels, in which the electrons can skip from one to the other channel, 21 years ago. The research team has in the meantime realized this vision based on the results presented here. A further publication is therefore to follow shortly.

Sylvain Hermelin, Shintaro Takada, Michihisa Yamamoto, Seigo Tarucha, Andreas D. Wieck, Laurent Saminadayar, Christopher Bäuerle and Tristan Meunier are the authors of "Electrons surfing on a sound wave as a platform for quantum optics with flying electrons" (DOI: 10.1038/nature10416).
Source: Ruhr-University Bochum

Back to Table of contents

Primeur weekly 2011-09-26

Special

Steve Conway to highlight European HPC market at EGI Technical Forum ...

Exascale supercomputing

Appro and SDSC Gordon supercomputer to provide up to 35 million IOPS ...

"Stampede's" comprehensive capabilities to bolster U.S. open science computational resources ...

The Cloud

Bull and CA Technologies form a strategic alliance ...

Gresham Computing to launch Clareti Transaction Control ...

HP Channel Partners open new Cloud Centers of Excellence ...

IBM expands Cloud delivery of smarter commerce ...

'Managed application services added to Interoute’s unified computing portfolio ...

Midas Medici's CIMCORP wins $3 million contract for data centre solutions in Brazil ...

Oracle successfully completes Continua Health Alliance interoperability testing ...

SDSC announces scalable, high-performance data storage Cloud ...

Desktop Grids

e-ScienceTalk Briefing on Desktop Grids has just appeared ...

BOINC integrated with Wordpress ...

OurGrid version 4.2.6 now released ...

EuroFlash

Bright Computing now resells Altair PBS Professional Workload Manager, delivering HPC operational efficiencies and cost savings ...

Repsol and BSC create a joint research centre in Spain ...

Sailing Mediterranean ICT seas - Boosting high-speed ICT infrastructures across Europe and Mediterranean ...

Mini-quantum computer passes test ...

Like fish on waves: electrons go surfing ...

USFlash

Emerson Network Power doubles the life span of VME boards ...

Retailers generate high-volume sales with IBM solution for smarter commerce ...

Nearly half of IT decision makers favour solid-state storage technology ...

University of Minnesota Supercomputing Institute adds Dell Terascala HPC Storage Solution to Itasca system ...

Oracle announces the immediate availability of the Oracle Database Appliance ...

Oracle Financial Services Revenue Management and Billing running with Oracle Exadata Database Machine delivers extreme performance ...

Major supercomputing boost for University of Canterbury ...

Post-silicon computing ...