Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A new step towards quantum computers

30.03.2009
RUB Physicists get into a SPIN again
Alignment and Measurement of Electron Spin

The intrinsic rotation of electrons - the "spin" - remains unused by modern electronics. If use as an information carrier were possible, the processing power of electronic components would suddenly increase to a multiple of the present capacity.

In cooperation with colleagues from Dortmund, St. Petersburg and Washington, Bochum physicists have now succeeded in aligning electron spin, bringing it to a controlled "waver" and reading it out. The electron spin can also be realigned as required at any time using optical pulses.

"This is the first, important step toward addressing these "quantum bits", which will form an integral part of data transfer systems and processors in the future", exclaimed Prof. Andreas Wieck. The researchers have published their report in NATURE Physics.

Complex Calculations in Minimum Space

The entirety of present day electronics is based on electrical charges: If a memory cell (bit) has an electrical charge, it represents a logical "1", if no charge is present this is a logical "0". However electrons have more than just a charge - they spin like a top around their own axis, producing a magnetic field, similar to the earth. This spin can be accelerated or decelerated by applying an external magnetic field. The "top" begins to waver and its axis tips to virtually any desired angle. If these manifold possibilities were used as information carriers, it would be possible to store a great deal more information than just "0" and "1" with an electron. Moreover adjacent electrons could be moved into various configurations, because they exert forces on one another in the same manner as two magnets on a bulletin board. This phenomenon would provide a significantly more complex base for data storage and processing. Even a small quantity of these so-call quantum bits (qubits), would allow extremely complex calculations, for which millions of bits are required today.

Confinement of Spins in Indium-Arsenic Islands

Naturally one single electron has only a very small measureable effect. For this reason individual electron measurements can only be performed with great difficulty using highly sensitive instruments. This is why the international research team has specialized in confining nearly one million electrons each in virtually identical indium-arsenic islands ("quantum dots") and totaling their effect. These "ensemble" measurements provide signals which are stronger by a magnitude of six, making them very sturdy and allowing them to be recorded easily.

"Contrary to the preconceptions of many international competitors, all associated electron spins exhibit precisely the same behavior and the microscopic effects can therefore be measured very easily" stated Wieck.

Optical Switching of Quantum Dots

In the study published in "NATURE" the physicists were not only successful in aligning the electron spin; they also managed to rotate it optically using a laser pulse in any desired direction at any time and read this direction out with a further laser pulse. This is the first important step towards "addressing" and influencing qubits. "The interesting factor here is that these electrons are enclosed in solid bodies, so we no longer need complex high vacuum equipment and light occlusion on all sides to keep them permanently in a module as in quantum optics " stressed Prof. Wieck. In Bochum the extremely high vacuum is required only once during production of the quantum dot; after that the semiconductor system is sealed against air ingress, has a long service life and is just as reliable as all transistors and memory cells already in use today.

Title picture

A. Greilich, Sophia E. Economou, S. Spatzek, D. R. Yakovlev, D. Reuter, A. D. Wieck, T. L. Reinecke & M. Bayer: Ultrafast optical rotations of electron spins in quantum dots. in: NATURE Physics, 22.3.2009, DOI 10.1038/NPHYS1226

Further information

Prof. Dr. Andreas Wieck, Chair for Applied Solid State Physics at the Ruhr University in Bochum, Tel.: 0234/32-28786, E-Mail: andreas.wieck@rub.de

Editor: Meike Drießen

Dr. Josef König | idw
Further information:
http://www.ruhr-uni-bochum.de/

More articles from Physics and Astronomy:

nachricht Engineering team images tiny quasicrystals as they form
18.08.2017 | Cornell University

nachricht Astrophysicists explain the mysterious behavior of cosmic rays
18.08.2017 | Moscow Institute of Physics and Technology

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: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

On the way to developing a new active ingredient against chronic infections

21.08.2017 | Life Sciences

Smart Computers

21.08.2017 | Information Technology

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>