Scientists give light a light squeeze and defy the laws of physics

1 Sep 2015

The experiment in action at the University of Cambridge. Image via Mete Atature

They said it couldn’t be done, but scientists working on photonics research have conducted an experiment that has managed to squeeze particles of light, defying a 34-year belief.

The concept of giving light a light squeeze is something that was known about in the field of quantum physics but had never been observed, putting it in the category of ‘near-impossible’ for science.

But now, a team from the University of Cambridge has published the findings of its experiment in nature in which it claims to have squeezed photons with the help of an artificially constructed atom – superior to natural atoms – known as a semiconductor quantum dot.

In doing so, the measuring equipment designed for this experiment was able to observe the scattering light, the tell-tale sign that it had indeed been squeezed, thereby proving the theory drawn up in 1981.

According to the university, the end-effect of squeezing light creates a light that is referred to as having a ‘low-noise’ profile and could be useful for technology that detects faint signals, particularly gravitational waves.

Light squeeze diagram

The right panel of the diagram shows the ‘technically impossible’ sign that light was squeezed. Image via Mete Atature

This low-noise, known as vacuum fluctuations, still exists even when, on a non-quantum level, there is no light.

The squeezing of light was then achieved by limiting the noise into a lower-than-vacuum state, which resulted in the squeezed appearance.

“It’s a very bizarre effect that goes completely against our senses and expectations about what photons should do,” said Prof Mete Atature, from the Cavendish Laboratory at the Department of Physics.

Explaining the concept further, Atature added: “If you look at a flat surface, it seems smooth and flat, but we know that if you really zoom in to a super-fine level, it probably isn’t perfectly smooth at all.

“The same thing is happening with vacuum fluctuations. Once you get into the quantum world, you start to get this fine print. It looks like there are zero photons present, but actually there is just a tiny bit more than nothing.”

Colm Gorey was a senior journalist with Silicon Republic