December 7, 2022

Quantum fluctuations can jiggle objects on the human scale

A team led by researchers at MIT LIGO Laboratory has measured the effects of quantum fluctuations on objects at the human scale. 

The researchers reported observing that quantum fluctuations, tiny as they may be, can nonetheless “kick” an object as large as the 40-kilogram mirrors of the National Science Foundation’s Laser Interferometer Gravitational-wave Observatory (LIGO), causing them to move by a tiny degree, which the team was able to measure.

LIGO is designed to detect gravitational waves arriving at the Earth from cataclysmic sources millions to billions of light years away. It comprises two twin detectors, one in Hanford, Washington, and the other in Livingston, Louisiana. Each detector is an L-shaped interferometer made up of two 4-kilometer-long tunnels, at the end of which hangs a 40-kilogram mirror.

It turns out the quantum noise in LIGO’s detectors is enough to move the large mirrors by 10-20 meters—a displacement that was predicted by quantum mechanics for an object of this size, but that had never before been measured.

The researchers used a special instrument that they designed, called a quantum squeezer, to “manipulate the detector’s quantum noise and reduce its kicks to the mirrors, in a way that could ultimately improve LIGO’s sensitivity in detecting gravitational waves“. 

Through these quantum correlations, the team was able to squeeze the quantum noise, and the resulting mirror displacement, down to 70 percent its normal level. (Phys.org)

The paper has been published in Nature.

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