Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Quantum Physics - What Darwin Missed

20.10.2008
RELATIONSHIPS BETWEEN QUANTUM DOTS - STABILITY AND REPRODUCTION
Theoretical proof of stable and measurable states extending over two quantum dots and creating offspring has now been provided for the first time. This supports the notion of what is known as Quantum Darwinism, which makes the selection and reproduction of quantum mechanical states responsible for the way in which our reality is perceived. These results of an Austrian Science Fund FWF project were recently published in Physical Review Letters and will play a part in the future development of quantum information technology.

Quantum dots are nanoscopic structures which are so small that they are subject to the laws of quantum physics. This means, among other things, that electrons in quantum dots assume states with specific energy values. If these electron states are measured, they interact with the environment. As a result of this interaction, some electron states mix with each other or with those of the environment and become energetically smeared. Some of the original states, however, are robust and retain their energy values. These are known as "pointer states" and, until now, they could only be proved to exist for single quantum dots.

STABLE RELATIONS...
A team from the Institute of Physics at the University of Leoben, together with colleagues from the Arizona State University, has succeeded in proving the existence of new kinds of pointer states in coupled quantum dots on a semiconductor layer structure made from aluminium arsenide and gallium arsenide. "We have called these pointer states of two coupled quantum dots biparpite pointer states. They are an exciting discovery because they extend over two quantum dots and thus represent an analogon to molecules. Their interaction with the environment means that values such as electrical resistance can be measured," explains Dr. Roland Brunner, a member of Professor Friedemar Kuchar's team.

...CREATE OFFSPRING
The team also succeeded in finding clear indications of Quantum Darwinism, that is to say the notion that during interaction with the environment only the "strongest" states - the pointer states - remain stable and are able to create offspring. To provide proof of this notion, the group working with Brunner and Kuchar calculated the probabilitiy densities of the electrons in the system for several quantum dots in series. Such a system corresponds to a waveguide for electrons in which the electric current is determined by transmitted electron waves. Calculating the electron probability density for the energy of the bipartite pointer state demonstrated that the three-dimensional pattern for this probability density is identical for many different electron waves. In other words, offspring of the bipartite pointer state are present. This result is internationally accepted as proof that quantum Darwinism actually occurs.
Although quantum dots were investigated on a purely theoretical basis in this FWF project, they have definite practical benefits. An earlier publication has already created a link to a measured parameter - electrical resistance. What's more, quantum dots can form the quintessential basis for future quantum information technology components such as quantum computers.
These computers could use the robustness of bipartite pointer states to describe more than just the states "0" or "1" of the binary logic that represents the performance spectrum of conventional computers. However, a critical factor for the development of quantum computers is the means to measure the states, i.e. the interface to the outside "classical" world.

Only if several measurements record the same state can a measurement or result be deemed objective. In order to achieve this, however, such a state must create offspring as postulated by Quantum Darwinism. Further confirmation of such offspring creation was provided by this project.

Original publication: "Coupling-Induced Bipartite Pointer States in Arrays of Electron Billiards: Quantum Darwinism in Action?" R. Brunner, R. Akis, D.K. Ferry, F. Kuchar & R. Meisels, Phys. Rev. Letters 101, 024102 (2008).

Scientific Contact:
Dr. Roland Brunner
University of Leoben
Institute of Physics
8700 Leoben
Austria
T +43 / 3842 / 402 - 4601
E roland.brunner@unileoben.ac.at
Austrian Science Fund FWF:
Mag. Stefan Bernhardt
Haus der Forschung
Sensengasse 1
1090 Vienna
Austria
T +43 / 1 / 505 67 40 - 8111
E stefan.bernhardt@fwf.ac.at
Copy Editing & Distribution:
PR&D - Public Relations for Research & Education Campus Vienna Biocenter 2 1030 Vienna Austria T +43 / 1 / 505 70 44 E contact@prd.at W http://www.prd.at

Mag. Stefan Bernhardt | Austrian Science Fund FWF
Further information:
http://www.fwf.ac.at
http://www.fwf.ac.at/en/public_relations/press/pv200810-en.html

Further reports about: Darwinism FWF Physic Quantum quantum computers quantum dots

More articles from Physics and Astronomy:

nachricht Breakthrough with a chain of gold atoms
17.02.2017 | Universität Konstanz

nachricht New functional principle to generate the „third harmonic“
16.02.2017 | Laser Zentrum Hannover e.V.

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

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>