Quantum light helps measurement
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By using "squeezed" quantum light, the researchers proved they could measure spectacularly small distances even when the target - a phase of light - was moving around. 
Image: krystiannawrocki/iStockphoto

An international team of physicists has pushed the boundaries on ultra-precise measurement by harnessing the unusual properties of quantum light waves in a new way.

While the ability to measure spectacularly small distances using “squeezed” light has been previously demonstrated, the researchers say it’s now possible to do this even while the target – a phase of light – is moving around.

An Australian-Japanese research collaboration made the breakthrough in an experiment conducted at the University of Tokyo, the results of which were published today in the prestigious journal Science.

“What we’ve done is make the world’s most precise measurement of the phase of a beam of light,” says Professor Elanor Huntington from UNSW Canberra and the ARC Centre for Quantum Computation and Communication Technology.

The group simulated the phase disturbances that a light beam might experience when travelling between two points, such as down an optical fibre line or between two satellites in space. 

They then applied their novel measurement technique to determine the margin of error – which was smaller than anything achievable with conventional light sources, such as lasers.

“Because the phase of a light beam changes whenever it passes through or bounces off an object, being able to measure that change is a very powerful tool,” says Professor Howard Wiseman, leader of the international theoretical team from Griffith University’s Centre for Quantum Dynamics.

Professor Huntington, who directed the Australian experimental contribution, says the finding will have important implications for ultra secure quantum communication, which is associated with teleportation, and detecting the existence of yet-elusive gravitational waves.  

It is also significant for the field of measurement, she says, which underpins a range of applications, such as gauging time, mass, distance, and the presence of molecules or sub-atomic matter. 

Editor's Note: Original news release can be found here.