Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers squeeze light out of quantum dots

06.04.2009
Physics breakthrough could lead to forward leaps in lasers, telecom and optical computing

McGill University researchers have successfully amplified light with so-called "colloidal quantum dots," a technology that had been written off by many as a dead-end.

Over the last 15 years, repeated quantum dot research efforts failed to deliver on expected improvements in amplification, and many researchers started to believe that an unknown but insurmountable law of physics was blocking their path. Essentially, they said, quantum dots would simply never work well for one of their primary applications.

However, after extensive research, Professor Patanjali (Pat) Kambhampati and colleagues at McGill University's Department of Chemistry determined that colloidal quantum dots do indeed amplify light as promised. The earlier disappointments were due to accidental roadblocks, not by any fundamental law of physics, the researchers said. Their results were published in the March 2009 issue of Physical Review Letters.

Colloidal quantum dots can actually be painted directly on to surfaces, and this breakthrough has enormous potential significance for the future of laser technology, and by extension, for telecommunications, next-generation optical computing and an innumerable array of other applications.

Lasers – beams of high-powered coherent light – have applications in dozens of fields, most notably in telecommunications, where they are used to transmit voice and data over fibre-optic cables. Like sound, radio waves or electricity, laser signals gradually lose power over distance and must be passed through an amplifier to maintain signal strength. Until now, the best available amplification technology was the quantum well, a thin sheet made of semi-conductor material which confines electrons to a one-dimensional plane, and consequently amplifies light. Colloidal quantum dots perform a similar function, but in a three-dimensional box-like structure instead of a flat sheet.

"Everyone expected this little box to be significantly better than a thin sheet," Kambhampati said. "You'd require less electrical power, and you wouldn't need to use arrays of expensive cooling racks. The idea was to make the lasing process as cheap as possible. But the expected results were not really there. So people said 'let's forget about the quantum dot' and they tried rods or onion shapes. It became a game of making a whole soup of different shapes and hoping one of them would work.

"In our view," he continued, "no one had figured out how the simple, prototypical quantum dot actually worked. And if you don't know that, how are you going to rationally construct a device out of it?"

In the end, Kambhampati and his colleagues discovered that the major problem lay in the way researchers had been powering their quantum dot amplifiers.

"We discovered that there was nothing fundamentally wrong with the dots. If you weren't careful in your measurements, when powering the quantum dot, you would accidentally create a parasitic effect that would kill the amplification." he said. "Once we understood this, we were able to take a quantum dot that no one believed could amplify anything, and turned it into the most efficient amplifier ever measured, as far as I know."

ABOUT McGILL UNIVERSITY

McGill University, founded in Montreal, Que., in 1821, is Canada's leading post-secondary institution. It has two campuses, 11 faculties, 10 professional schools, 300 programs of study and more than 33,000 students. McGill attracts students from more than 160 countries around the world. Almost half of McGill students claim a first language other than English – including 6,000 francophones – with more than 6,200 international students making up almost 20 per cent of the student body.

Mark Shainblum | EurekAlert!
Further information:
http://www.mcgill.ca

More articles from Physics and Astronomy:

nachricht First chip-scale broadband optical system that can sense molecules in the mid-IR
24.05.2018 | Columbia University School of Engineering and Applied Science

nachricht Nuclear physicists leap into quantum computing with first simulations of atomic nucleus
24.05.2018 | DOE/Oak Ridge National Laboratory

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: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

When corals eat plastics

24.05.2018 | Ecology, The Environment and Conservation

Surgery involving ultrasound energy found to treat high blood pressure

24.05.2018 | Medical Engineering

First chip-scale broadband optical system that can sense molecules in the mid-IR

24.05.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>