Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Quantum doughnuts slow and freeze light at will

10.03.2009
Research led by the University of Warwick has found a way to use doughnut shaped by-products of quantum dots to slow and even freeze light, opening up a wide range of possibilities from reliable and effective light based computing to the possibility of "slow glass".

The key to this new research is the “exciton”. This describes the pairing of an electron that has been kicked into a higher energy state by a photon, with a hole or gap it (or another electron) leaves within the shell or orbit around the nucleus of an atom.

Despite its new high energy state the electron remains paired with one of the holes or positions that has been vacated by electrons moving to a higher energy state. When an electron’s high energy state decays again it is drawn back to the hole it is linked to and a photon is once again emitted.

That cycle usually happens very quickly but if one could find a way to freeze or hold an exciton in place for any length of time one could delay the reemitting of a photon and effectively slow or even freeze light.

The researchers, led by PhD researcher Andrea Fischer and Dr. Rudolf A. Roemer from the University of Warwick’s Department of Physics, looked at the possibilities presented by some tiny rings of matter accidentally made during the manufacture quantum dots. When creating these very small quantum dots of a few 10-100nm in size physicists some times cause the material to splash when depositing it onto a surface leaving, not a useful dot, but a doughnut shaped ring of material. Though originally created by accident these “Aharonov-Bohm nano rings” are now a source of study in their own right and in this case seemed just the right size for enclosing an exciton. However simply being this useful size does not, in itself, allow them to contain or hold an exciton for any length of time.

However remarkably the Warwick led research team have found that if a combination of magnetic and electric fields is applied to these nano-rings they can actually then simply tune the electric field to freeze an exciton in place or let it collapse and re-emit a photon.

While other researchers have used varying exotic states of matter to dramatically slow the progress of light this is the first time a technique has been devised to completely freeze and release individual photons at will.

Dr Roemer said:

“This has significant implications for the development of light based computing which would require an effective and reliable mechanism such as this to manipulate light. “

The technique could also be used to develop a “buffer” of incoming photons which could re-release them in sequence at a later date thus creating an effect not unlike the concept of “Slow Glass” first suggested by science fiction author Bob Shaw several decades ago.

The new research paper is entitled “Exciton storage in a nanoscale Aharonov-Bohm ring with electric field tuning" by University of Warwick PhD student Andrea M.Fischer, Dr Rudolf Roemer (University of Warwick) Vivaldo L. Campo Jr. (Universidade Federal de Sao Carlos-UFSCar, Brazil), and Mikhail E. Portnoi (University of Exeter), and has just been published in Physical Review Letters (PRL)

For further information please contact:

Dr. Rudolf A. Roemer, Department of Physics, University of Warwick,
Tel +44 (0)2476 574328 r.roemer@warwick.ac.uk
Peter Dunn, Press and Media Relations Manager
Communications Office, University House,
University of Warwick, Coventry, CV4 8UW, United Kingdom
email: p.j.dunn@warwick.ac.uk Tel: +44 (0)24 76 523708 Mobile/Cell: +44 (0)7767 655860

Dr. Rudolf A. Roemer | EurekAlert!
Further information:
http://www.warwick.ac.uk

More articles from Physics and Astronomy:

nachricht Active pits on Rosetta’s comet
03.07.2015 | Max Planck Institute for Solar System Research, Göttingen

nachricht Researchers find the macroscopic Brownian motion phenomena of self-powered liquid metal motors
02.07.2015 | Science China Press

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: Viaducts with wind turbines, the new renewable energy source

Wind turbines could be installed under some of the biggest bridges on the road network to produce electricity. So it is confirmed by calculations carried out by a European researchers team, that have taken a viaduct in the Canary Islands as a reference. This concept could be applied in heavily built-up territories or natural areas with new constructions limitations.

The Juncal Viaduct, in Gran Canaria, has served as a reference for Spanish and British researchers to verify that the wind blowing between the pillars on this...

Im Focus: X-rays and electrons join forces to map catalytic reactions in real-time

New technique combines electron microscopy and synchrotron X-rays to track chemical reactions under real operating conditions

A new technique pioneered at the U.S. Department of Energy's Brookhaven National Laboratory reveals atomic-scale changes during catalytic reactions in real...

Im Focus: Iron: A biological element?

Think of an object made of iron: An I-beam, a car frame, a nail. Now imagine that half of the iron in that object owes its existence to bacteria living two and a half billion years ago.

Think of an object made of iron: An I-beam, a car frame, a nail. Now imagine that half of the iron in that object owes its existence to bacteria living two and...

Im Focus: Thousands of Droplets for Diagnostics

Researchers develop new method enabling DNA molecules to be counted in just 30 minutes

A team of scientists including PhD student Friedrich Schuler from the Laboratory of MEMS Applications at the Department of Microsystems Engineering (IMTEK) of...

Im Focus: Bionic eye clinical trial results show long-term safety, efficacy vision-restoring implant

Patients using Argus II experienced significant improvement in visual function and quality of life

The three-year clinical trial results of the retinal implant popularly known as the "bionic eye," have proven the long-term efficacy, safety and reliability of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

World Conference on Regenerative Medicine in Leipzig: Last chance to submit abstracts until 2 July

25.06.2015 | Event News

World Conference on Regenerative Medicine: Abstract Submission has been extended to 24 June

16.06.2015 | Event News

MUSE hosting Europe’s largest science communication conference

11.06.2015 | Event News

 
Latest News

Siemens receives order for offshore wind power plant in Great Britain

03.07.2015 | Press release

'Déjà vu all over again:' Research shows 'mulch fungus' causes turfgrass disease

03.07.2015 | Agricultural and Forestry Science

Discovery points to a new path toward a universal flu vaccine

03.07.2015 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>