Quantum Physics: Scientists 'Squeeze' Light One Particle at a Time

Scientists have figured out how to "squeeze" light one particle at a time. They've successfully measured particles in an experiment that had once been written off as impossible to observe.

Squeezing is a strange phenomenon of quantum physics. It creates a very specific form of light which is "low-noise" and is potentially useful in technology designed to pick up faint signals, such as the detection of gravitational waves. The standard approach to accomplish this feat involves firing an intense laser beam at a material, usually a non-linear crystal, which produces the desired effect.

However, for years a theory has existed that there exists another possible technique to accomplish this goal. Now, researchers have proven that it can be used.

In this latest study, the researchers successfully demonstrated the squeezing of individual light particles, or photons, using an artificially constructed atom, known as a semiconductor quantum dot. Thanks to the enhanced optical properties of this system and the technique used to make the measurements, the scientists were able to observe the light as it was scattered, and proved that it had indeed been squeezed.

"It's one of those cases of a fundamental question that theorists came up with, but which, after years of trying, people basically concluded it is impossible to see for real-if it's there at all," said Mete Atature, one of the researchers, in a news release. "We managed to do it because we now have artificial atoms with optical properties that are superior to natural atoms. That meant we were able to reach the necessary conditions to observe this fundamental property of photons and prove that this odd phenomenon of squeezing really exists at the level of a single photon. It's a very bizarre effect that goes completely against our senses and expectations about what photons should do."

The findings are published in the journal Nature.

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