03 September 2010
'Quantum cats' help future communications
Researchers at the US National Institute of Standards and Technology have created 'quantum cats' made of photons. This is said to boost the prospects for manipulating light in new ways to enhance precision measurements as well as computing and communications based on quantum physics.
In the NIST experiments, light pulses were produced that possessed two exactly opposite phases. Physicists call this an optical 'Schrödinger's cat'. NIST says its quantum cat is the first to be made by detecting three photons at once and is one of the largest and most well defined 'cat states' made from light.
According to NIST, a 'cat state' is a curiosity of the quantum world, where particles can exist in 'superpositions' of two opposite properties simultaneously. The term 'cat state' refers to Erwin Schrödinger's 1935 theoretical notion of a cat that is both alive and dead simultaneously.
"This is a new state of light [that has been] predicted in quantum optics for a long time," said NIST research associate Thomas Gerrits, lead author of a soon to be published paper describing the achievement. "The technologies that enable us to get these really good results are ultrafast lasers, knowledge of the type of light needed to create the cat state and photon detectors that can actually count individual photons."
The NIST team created its optical cat state by using an ultrafast laser pulse to excite special crystals to create a form of light known as a squeezed vacuum, which contains only even numbers of photons. A specific number of photons were subtracted from the squeezed vacuum using a beam splitter. The photons were identified with a NIST sensor that efficiently detects and counts individual photons.
Depending on the number of photons subtracted, the remaining light is in a state that is a good approximation of a quantum cat said Gerrits.
Author
Graham Pitcher
Supporting Information
Websites
http://www.nist.gov
Companies
NIST
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