Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Light Touch: Controlling the Behavior of Quantum Dots

(Top) Cross-section scanning tunneling microscope (STM) image shows indium arsenide quantum dot regions embedded in gallium arsenide. Each 'dot' is approximately 30 nanometers long–faint lines are individual rows of atoms. (Color added for clarity.) Credit: J.R. Tucker
(Bottom) Schematic of NIST-JQI experimental set up. Orienting the resonant laser at a right angle to the quantum dot light minimizes scattering. Credit: Solomon/NIST
(Top) Cross-section scanning tunneling microscope (STM) image shows indium arsenide quantum dot regions embedded in gallium arsenide. Each 'dot' is approximately 30 nanometers long–faint lines are individual rows of atoms. (Color added for clarity.) Credit: J.R. Tucker (Bottom) Schematic of NIST-JQI experimental set up. Orienting the resonant laser at a right angle to the quantum dot light minimizes scattering. Credit: Solomon/NIST

Abstract:
Researchers from the National Institute of Standards and Technology (NIST) and the Joint Quantum Institute (JQI), a collaborative center of the University of Maryland and NIST, have reported a new way to fine-tune the light coming from quantum dots by manipulating them with pairs of lasers. Their technique, published in Physical Review Letters,* could significantly improve quantum dots as a source of pairs of "entangled" photons, a property with important applications in quantum information technologies. The accomplishment could accelerate development of powerful advanced cryptography applications, projected to be a key 21st-century technology.

Light Touch: Controlling the Behavior of Quantum Dots

GAITHERSBURG, MD | Posted on August 19th, 2008

Entangled photons are a peculiar consequence of quantum mechanics. Tricky to generate, they remain interconnected even when separated by large distances. Merely observing one instantaneously affects the properties of the other. The entanglement can be used in quantum communication to pass an encryption key that is by its nature completely secure, as any attempt to eavesdrop or intercept the key would be instantly detected. One goal of the NIST-JQI team is to develop quantum dots as a convenient source of entangled photons.

Quantum dots are nanoscale regions of a semiconductor material similar to the material in computer processors but with special properties due to their tiny dimensions. Though they can be composed of tens of thousands of atoms, quantum dots in many ways behave almost as if they were single atoms. Unfortunately, almost is not good enough when it comes to the fragile world of quantum cryptography and next-generation information technologies. When energized, a quantum dot emits photons, or "particles" of light, just as a solitary atom does. But imperfections in the shape of a quantum dot cause what should be overlapping energy levels to separate. This ruins the delicate balance of the ideal state required to emit entangled photons.

To overcome this problem, the NIST-JQI team uses lasers to precisely control the energy levels of quantum dots, just as physicists have been doing with actual single atoms since the mid-1970s and, much more recently, with the artificial quantum dot variety. With their customized set-up, which includes two lasers—one shining from above the quantum dot and the other illuminating it from the side—the researchers were able to manipulate energy states in a quantum dot and directly measure its emissions. By adjusting the intensity of the laser beams, they were able to correct for imperfection-caused variations and generate more ideal signals. In so doing, the team was the first to demonstrate that laser-tuned quantum dots can efficiently generate photons one at a time, as required for quantum cryptography and other applications.

While the device currently still requires quite cold temperatures and sits in a liquid helium bath, it is compact enough to fit in the palm of your hand—an elegant setup that could be eventually implemented in quantum cryptography applications.

* A. Muller, W. Fang, J. Lawall and G.S. Solomon. Emission spectrum of a dressed exciton-biexciton complex in semiconductor quantum dot. Physical Review Letters, 101, 027401 (2008), posted online July 11, 2008.

####

About NIST
Founded in 1901, NIST is a non-regulatory federal agency within the U.S. Department of Commerce. NIST's mission is to promote U.S. innovation and industrial competitiveness by advancing measurement science, standards, and technology in ways that enhance economic security and improve our quality of life.

For more information, please click here

Contacts:
Mark Bello

(301) 975-3776

Copyright © NIST

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Graphene holds up under high pressure: Used in filtration membranes, ultrathin material could help make desalination more productive April 24th, 2017

Nanoparticle vaccine shows potential as immunotherapy to fight multiple cancer types April 24th, 2017

Russian scientists create new system of concrete building structures: Sientists of Peter the Great Saint-Petersburg Polytechnic University developed a new construction technology April 24th, 2017

Nanomechanics, Inc. Unveils New Product at ICMCTF Show April 25th: Nanoindentation experts will launch the new Gemini that measures the interaction of two objects that are sliding across each other – not merely making contact April 21st, 2017

Quantum Computing

Harris & Harris Group Issues Its Financial Statements as of December 31, 2016, Posts Its Annual Shareholder Letter, And Will Host a Conference Call for Shareholders on Friday, March 17, 2017 March 15th, 2017

Sorting machine for atoms:Researchers at the University of Bonn clear a further hurdle on the path to creating quantum computers February 10th, 2017

First ever blueprint unveiled to construct a large scale quantum computer February 3rd, 2017

Chiral quantum optics: A new research field with bright perspectives January 31st, 2017

Discoveries

Graphene holds up under high pressure: Used in filtration membranes, ultrathin material could help make desalination more productive April 24th, 2017

Nanoparticle vaccine shows potential as immunotherapy to fight multiple cancer types April 24th, 2017

Russian scientists create new system of concrete building structures: Sientists of Peter the Great Saint-Petersburg Polytechnic University developed a new construction technology April 24th, 2017

Two-dimensional melting of hard spheres experimentally unravelled after 60 years: First definitive experimental evidence of two-dimensional melting of hard spheres April 21st, 2017

Announcements

Graphene holds up under high pressure: Used in filtration membranes, ultrathin material could help make desalination more productive April 24th, 2017

Nanoparticle vaccine shows potential as immunotherapy to fight multiple cancer types April 24th, 2017

Russian scientists create new system of concrete building structures: Sientists of Peter the Great Saint-Petersburg Polytechnic University developed a new construction technology April 24th, 2017

Two-dimensional melting of hard spheres experimentally unravelled after 60 years: First definitive experimental evidence of two-dimensional melting of hard spheres April 21st, 2017

Quantum Dots/Rods

Nanoparticles open new window for biological imaging: “Quantum dots” that emit infrared light enable highly detailed images of internal body structures April 10th, 2017

Particle Works creates range of high performance quantum dots February 23rd, 2017

Strem Chemicals and Dotz Nano Ltd. Sign Distribution Agreement for Graphene Quantum Dots Collaboration February 21st, 2017

Carbon dots dash toward 'green' recycling role: Rice scientists, colleagues use doped graphene quantum dots to reduce carbon dioxide to fuel December 18th, 2016

Photonics/Optics/Lasers

Method improves semiconductor fiber optics, paves way for developing devices April 16th, 2017

AIM Photonics Presents Cutting-Edge Integrated Photonics Technology Developments to Packed House at OFC 2017, the Optical Networking and Communication Conference & Exhibition April 11th, 2017

Photonics breakthough paving the way for improved wireless communication systems: The work could bolster the wireless revolution underway with efficiencies several orders of magnitude April 5th, 2017

Controlling forces between atoms, molecules, promising for ‘2-D hyperbolic’ materials April 4th, 2017

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project