Shape Matters When Light Meets Atom, New Study Says

First Posted: Dec 07, 2016 03:20 AM EST

A team of scientists has found that a photon's shape matters when light meets atom.

Published in the journal Nature Communications, a new study shows that a photon's shape could affect how it is absorbed by a single atom.

Vision entails photons of light, which are packets of energy, interacting with the atoms in what a person is looking at. Some of these photons reflect off, reaching the eyes. On the other hand, other photons are absorbed.

"Our experiments look at the most fundamental interaction between matter and light," Victor Leong, a co-author of the study, said in a press release by the Centre for Quantum Technologies.

However, it is hard to imagine that a photon could take a shape at all. For one, photons are massless invisible units of light. How could something without mass occupy a geometric space?

This is where the researchers at the National University Singapore come in. They devised a method for shaping photons with extreme precision, paving way for an unprecedented look at the light-matter interactions at atomic scales. They worked with Rubidium atoms and infrared photons. In fact, they found that shape plays a pivotal role in predicting whether an atom is likely to absorb a photon.

The team tested two different photon shapes, one rising in brightness and the other decaying. For over 1,500 hours, hundreds of millions of measurements showed that the chances that a single atom would absorb a single photon was just more than 4 percent. However, they also found that the chances of absorption depend on the photon's shape.

The researchers hope that their study would help shed light on the understanding of technologies that depend on light-matter interactions. The findings may pave way for the improvement of certain technologies like communication networks, computers and sensors. 

"The photon knocks the atom into an excited state. To build reliable devices, scientists will need to control the interaction. You can only engineer what you can understand," Alessandro Cere, a co-author, said in the press release. 

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