NIST researchers create 'quantum cats' made of light
Researchers at the National Institute of Standards and Technology (NIST) have created "quantum cats" made of photons (particles of light), boosting prospects for manipulating light in new ways to enhance precision measurements as well as computing and communications based on quantum physics. The NIST experiments, described in a forthcoming paper,* repeatedly produced light pulses that each possessed two exactly opposite properties—specifically, opposite phases, as if the peaks of the light waves were superimposed on the troughs. Physicists call this an optical Schrödinger's cat. NIST's 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 ever made from light. (Larger cat states have been created in different systems by other research groups, including one at NIST.)
A "cat state" is a curiosity of the quantum world, where particles can exist in "superpositions" of two opposite properties simultaneously. Cat state is a reference to German physicist Erwin Schrödinger's famed 1935 theoretical notion of a cat that is both alive and dead simultaneously.
"This is a new state of light, predicted in quantum optics for a long time," says NIST research associate Thomas Gerrits, lead author of the paper. "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 their 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 device called a beam splitter. The photons were identified with a NIST sensor that efficiently detects and counts individual photons (see "NIST Detector Counts Photons With 99 Percent Efficiency," NIST Tech Beat, Apr. 13, 2010, at www.nist.gov/eeel/optoelectronics/detector_041310.cfm.) Depending on the number of subtracted photons, the remaining light is in a state that is a good approximation of a quantum cat says Gerrits—the best that can be achieved because nobody has been able to create a "real" one, by, for instance, the quantum equivalent to superimposing two weak laser beams with opposite phases.
- Etched quantum dots shape up as single photon emitters, NIST tests showThu, 24 Feb 2011, 9:03:24 EST
- NIST advances single photon management for quantum computersThu, 20 Jan 2011, 11:06:18 EST
- Light touch: Controlling the behavior of quantum dotsTue, 19 Aug 2008, 17:56:36 EDT
- This little light of mine: Changing the color of single photons emitted by quantum dotsThu, 14 Oct 2010, 14:06:57 EDT
- Physicists find way to control individual bits in quantum computersTue, 7 Jul 2009, 10:43:59 EDT
- NIST researchers create 'quantum cats' made of lightfrom Science CentricThu, 2 Sep 2010, 13:21:15 EDT
- Researchers Create 'Quantum Cats' Made of Lightfrom Newswise - ScinewsWed, 1 Sep 2010, 16:28:41 EDT
- Schrödinger's Cat Now Made Of Lightfrom Scientific BloggingWed, 1 Sep 2010, 14:14:16 EDT
- NIST researchers create 'quantum cats' made of lightfrom PhysorgWed, 1 Sep 2010, 12:28:37 EDT
- Researchers create 'quantum cats' made of lightfrom Science DailyWed, 1 Sep 2010, 12:28:08 EDT
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