Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button

Home > Press > Life Expectancy on the Rise - Even for Quantum States

"Time to relax: Intersubband relaxation time indicates the timeframe within which excited charge carriers remain at an elevated energy level before returning to their original state."

Credit: DI Patrick Rauter
"Time to relax: Intersubband relaxation time indicates the timeframe within which excited charge carriers remain at an elevated energy level before returning to their original state."
Credit: DI Patrick Rauter

Abstract:
For the first time, scientists have succeeded in measuring and controlling the lifetime of quantum states with potential use in optoelectronic chips. This achievement is highly significant for the ongoing development of this cutting-edge technology. The breakthrough involved measuring the intersubband relaxation time of charge states in silicon-germanium SiGe structures on a picosecond scale. Experiments have also shown that it is possible to control and extend these times. As a result, this body of work - currently published in Physical Review Letters and supported by the Austrian Science Fund FWF - represents a major advance in the development of data processing based on optoelectronic chips.

Life Expectancy on the Rise - Even for Quantum States

Vienna, Austria | Posted on April 14th, 2009

Transmitting information via light quanta (photons) is nothing new. That is precisely what every fibre optic cable does with exceptional efficiency. But the process that is both ultra fast and reliable over long distances fails when used in close quarters. At present, photon-based chip-to-chip communication is not possible in data processing. The problem is the photon sources. Due to its semiconductor structure, the raw material currently used to manufacture computer chips - silicon - does not allow the generation of photons by conventional means. However, unconventional means may provide a solution - and that is precisely what the group from the Institute of Semiconductor and Solid State Physics at the University of Linz is working on.

Laser on a Chip
One potential solution could be a quantum cascade laser based on a silicon-germanium (SiGe) heterostructure, which could allow the use of quantum-physical effects to generate laser light in the infrared range. "There are currently numerous fundamental issues that need to be clarified in terms of the way that SiGe heterostructures work and how they can be controlled," explains DI Patrick Rauter, a member of the group lead by Dr. Thomas Fromherz that is working on the use of these structures for optical applications. One key parameter is the intersubband relaxation time. This indicates the timeframe within which excited charge carriers of the SiGe remain at an elevated energy level before returning to their original state. The duration of this period is a key factor for the quantum cascade laser, as the length of time the charge carriers are in a state of excitation is closely linked with their capacity to emit light.

DI Rauter and his colleagues have now succeeded in accurately measuring this timeframe. They were supported in their work by the Foundation for Fundamental Research Matter - FOM, based in Rijnhuizen, Netherlands - and its free-electron laser FELIX. The laser beam of this device can be pulsed in picoseconds, which means it can be used to measure extremely fast processes.

Fractions of a Fraction of a Second
Using an experimental design, the group succeeded in determining that the intersubband relaxation time lasts for between 12 and 25 picoseconds, or 12 to 25 trillionths of a second. The laser beam of FELIX was split to allow the group to measure these extraordinarily short spaces of time. One beam was used to excite the charge carriers in the SiGe while the other - after a time delay - performed the actual measurement. During this process, a photoelectric current - which is determined by the intersubband relaxation time - was measured. DI Rauter on the measurements: "We were also able to extend the intersubband relaxation lifetime in a controlled manner. To do this, we applied an external electrical field to the sample. By altering this field, we were able to continuously tune the relaxation time between 12 and 25 picoseconds. In actual fact, we succeeded in doubling the relaxation time - a highly promising result."

Published in Physical Review Letters, the work also forms part of the FWF special research program IR-ON (InfraRed Optical Nanostructures). A total of ten working groups from Austria and Germany contribute to this program, which focuses amongst other semiconductors on SiGe compounds with nanostructures that should be conducive for use in optoelectronic chips. The work conducted by DI Rauter and his colleagues has enabled the program to move a quantum leap - or one small step - closer to this goal.

Original publication: Continuous Voltage Tunability of Intersubband Relaxation Times in Coupled Well Structures. P. Rauter, T. Fromherz, N. Q. Vinh, B. N. Murdin, G. Mussler, D. Grützmacher & G. Bauer, Phys. Rev. Lett. 102, 147401 (2009) DOI: 10.1103/PhysRevLett.102.147401

####

For more information, please click here

Contacts:
Scientific contact
DI. Patrick Rauter
University of Linz
Institute of Semiconductor and Solid State Physics
Altenbergerstr. 69
4040 Linz /Austria
Austria
T: T +43 / 650 / 2041693
E
E

Austrian Science Fund FWF
Mag. Stefan Bernhardt
Haus der Forschung
Sensengasse 1
1090 Vienna
Austria
T +43 / 1 / 505 67 40 - 8111
E

Copy Editing & Distribution
PR&D - Public Relations for Research & Education
Campus Vienna Biocenter 2
1030 Vienna
Austria
T +43 / 1 / 505 70 44
E

Copyright © Austrian Science Fund FWF

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

Lehigh engineer discovers a high-speed nano-avalanche: New findings published in the Journal of Electrochemical Society about the process involving transformations in glass that occur under intense electrical and thermal conditions could lead the way to more energy-efficient glas August 24th, 2016

Light and matter merge in quantum coupling: Rice University physicists probe photon-electron interactions in vacuum cavity experiments August 24th, 2016

New microchip demonstrates efficiency and scalable design: Increased power and slashed energy consumption for data centers August 24th, 2016

Tunneling nanotubes between neurons enable the spread of Parkinson's disease via lysosomes August 24th, 2016

Chip Technology

Light and matter merge in quantum coupling: Rice University physicists probe photon-electron interactions in vacuum cavity experiments August 24th, 2016

New microchip demonstrates efficiency and scalable design: Increased power and slashed energy consumption for data centers August 24th, 2016

New theory could lead to new generation of energy friendly optoelectronics: Researchers at Queen's University Belfast and ETH Zurich, Switzerland, have created a new theoretical framework which could help physicists and device engineers design better optoelectronics August 23rd, 2016

Down to the wire: ONR researchers and new bacteria August 18th, 2016

Optical computing/Photonic computing

New theory could lead to new generation of energy friendly optoelectronics: Researchers at Queen's University Belfast and ETH Zurich, Switzerland, have created a new theoretical framework which could help physicists and device engineers design better optoelectronics August 23rd, 2016

Hexagonal boron nitride semiconductors enable cost-effective detection of neutron signals: Texas Tech University researchers demonstrate hexagonal boron nitride semiconductors as a cost-effective alternative for inspecting overseas cargo containers entering US ports August 17th, 2016

Prototype chip could help make quantum computing practical: Built-in optics could enable chips that use trapped ions as quantum bits August 9th, 2016

Scientists discover light could exist in a previously unknown form August 6th, 2016

Discoveries

Lehigh engineer discovers a high-speed nano-avalanche: New findings published in the Journal of Electrochemical Society about the process involving transformations in glass that occur under intense electrical and thermal conditions could lead the way to more energy-efficient glas August 24th, 2016

Light and matter merge in quantum coupling: Rice University physicists probe photon-electron interactions in vacuum cavity experiments August 24th, 2016

New microchip demonstrates efficiency and scalable design: Increased power and slashed energy consumption for data centers August 24th, 2016

Tunneling nanotubes between neurons enable the spread of Parkinson's disease via lysosomes August 24th, 2016

Announcements

Lehigh engineer discovers a high-speed nano-avalanche: New findings published in the Journal of Electrochemical Society about the process involving transformations in glass that occur under intense electrical and thermal conditions could lead the way to more energy-efficient glas August 24th, 2016

Light and matter merge in quantum coupling: Rice University physicists probe photon-electron interactions in vacuum cavity experiments August 24th, 2016

New microchip demonstrates efficiency and scalable design: Increased power and slashed energy consumption for data centers August 24th, 2016

Tunneling nanotubes between neurons enable the spread of Parkinson's disease via lysosomes August 24th, 2016

Quantum nanoscience

Light and matter merge in quantum coupling: Rice University physicists probe photon-electron interactions in vacuum cavity experiments August 24th, 2016

Prototype chip could help make quantum computing practical: Built-in optics could enable chips that use trapped ions as quantum bits August 9th, 2016

Diamond-based light sources will lay a foundation for quantum communications of the future: Electrified quantum diamond can become the heart of quantum networks and computers of the future August 7th, 2016

Scientists discover light could exist in a previously unknown form August 6th, 2016

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







Car Brands
Buy website traffic