Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Decay used to construct quantum information

25.11.2013
Usually, when researchers work with quantum information, they do everything they can to prevent the information from decaying.

Now researchers at the Niels Bohr Institute, among others, have flipped things around and are exploiting the decay to create the so-called entanglement of atomic systems, which is the foundation for quantum information processing. The results are published in the scientific journal, Nature.


This is an artist's impression of the experiment. Four ions are trapped on a line. The outer Magnesium ions (green) cools the system by emitting light. Lasers are used to prepare the inner Beryllium ions (red) in an entangled state where one can not understand the state of the particles individually but have to consider the two ions as a whole. As opposed to previous experiments also the latter process happens by the emission of light.

Credit: (Credit NIST)

"When working with quantum information, you would normally seek to isolate the system from the environment in order to not get a disturbing interaction that can destroy the fragile quantum state. But this is very difficult to avoid completely. So we thought that you could perhaps take the opposite approach and instead of seeing decay as the enemy, look at it as a friend and take advantage of it," explains Anders Søndberg Sørensen, a professor of quantum optics at the Niels Bohr Institute at the University of Copenhagen.

Electrons leaping hither and thither

The problem is that the quantum system is affected by the environment and exchanges energy with it. The electrons in the atoms jump from one energy state to another and researchers consider this kind of jump to be decay, because the information stored in the electrons disappears into its surroundings.

"But with our method we let the quantum system 'talk' with its surroundings and create a control of the electrons' jumps so that they are precisely in the state we want them to be in, and in that way we make use of the interaction with the environment," explains PhD student Florentin Reiter, who developed the theoretical model for the method together with Anders Sørensen.

The research is a collaboration with the experimental research group lead by David Wineland (recipient of the Nobel Prize in physics last year) at the National Institute for Standards and Technology in Boulder Colorado, USA.

Kicking the electrons into place

The method is based on a chain of ions comprised of magnesium and beryllium. They are cooled down to near absolute zero at minus 273 degrees C. The magnesium atoms are just there as a kind of cooling element in the chain of ions, while the beryllium atoms are the active elements. Entanglement is created between the electrons of the beryllium ions using carefully controlled laser light.

"The trick lies in the combination of laser light," explains Florentin Reiter and continues "the electrons can be in four energy states and if they jump around and land in a 'wrong' state, they are simply 'kicked' by the laser and we continue until they are where they are supposed to be. In that way there is perfect entanglement. Unlike in the past, when you had to use carefully designed laser pulses to create entanglement, researchers can now just turn on the laser and grab a cup of coffee and when they come back the electrons are in the correct state."

Up until this point, the decay of quantum information has been the biggest obstacle to making a quantum computer. The new experiment is the first time the problem has been turned on its head and the decay has been used constructively in a quantum computer. The researchers hope that this might be a way to overcome some of the problems that have previously made it difficult to make quantum computers. The researchers are now working to make more advanced quantum information processors based on the same ideas. In particular, they hope that similar techniques can be used to correct errors in a quantum computer.

For more information contact:

Anders Søndberg Sørensen
Professor, Quantum Optics
Niels Bohr Institute
University of Copenhagen
+45 3532-5240
+45 2466-1377
anders.sorensen@nbi.dk
Florentin Reiter
PhD student
Quantum Optics
Niels Bohr Institute
University of Copenhagen
0046-7232-70262
reiter@nbi.dk

Gertie Skaarup | EurekAlert!
Further information:
http://www.nbi.dk

More articles from Physics and Astronomy:

nachricht Smooth propagation of spin waves using gold
26.06.2017 | Toyohashi University of Technology

nachricht A 100-year-old physics problem has been solved at EPFL
23.06.2017 | Ecole Polytechnique Fédérale de Lausanne

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: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Study shines light on brain cells that coordinate movement

26.06.2017 | Life Sciences

Smooth propagation of spin waves using gold

26.06.2017 | Physics and Astronomy

Switchable DNA mini-machines store information

26.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>