An optics technician inspects one of the mirrors in the LIGO gravity wave detector. Image: Matt Heintze/Caltech/MIT/LIGO Lab
A device built to improve the sensitivity of gravity wave detectors has been used to measure the unimaginably tiny pressure exerted by quantum fluctuations in laser light on a human-scale object.
The “quantum squeezer” instrument, which helps reduce quantum background “noise” in the Laser Interferometer Gravitational-wave Observatory, or LIGO, detectors showed the pressure of virtual particles popping into and out of existence is able to move 40-kilogram (88-pound) mirrors by 10-20 metres. The result was predicted by quantum theory but never before measured.
“A hydrogen atom is 10-10metres (across), so this displacement of the mirrors is to a hydrogen atom what a hydrogen atom is to us. And we measured that,” said Lee McCuller, a researcher at MIT’s Kavli Institute for Astrophysics and Space Research.
Nergis Mavalvala, the Marble Professor and associate head of the physics department at MIT, said humans, too, “every nanosecond of our existence, are being kicked around, buffeted by these quantum fluctuations.”
“It’s just that the jitter of our existence, our thermal energy, is too large for these quantum vacuum fluctuations to affect our motion measurably,” she said. ...