Binding Light In New Form Of Matter – Lightsaber Anyone?

Could physical objects one day be created from molecules of light? Image credit:

A new form of matter has been created as scientists get photons to bind together to form molecules.

Below one of the research leaders, Harvard Professor of Physics Mikhail Lukin, explains this phenomenon further.The ability of light to act in this way has long been theorised, but until now, this ‘photonic bound state’ had not been observed.

"Most of the properties of light we know about originate from the fact that photons are massless, and that they do not interact with each other. What we have done is create a special type of medium in which photons interact with each other so strongly that they begin to act as though they have mass, and they bind together to form molecules.

Getting photons to bind together in this way is not easy. The scientists from Harvard and MIT first had to use lasers to cool a cloud of rubidium atoms to just above absolute zero (around 273oC) under vacuum conditions.

Then the team fired single photons into the atoms, which pass energy to the surrounding atoms along their trajectory, before exiting the cloud. Lukin explains:

"When the photon exits the medium, its identity is preserved. It's the same effect we see with refraction of light in a water glass. The light enters the water, it hands off part of its energy to the medium, and inside it exists as light and matter coupled together, but when it exits, it's still light. The process that takes place is the same it's just a bit more extreme – the light is slowed considerably, and a lot more energy is given away than during refraction."

However, when two photons are fired into the cloud together, something astounding happens – the photons leave the cloud together as a single molecule.

The reason for this binding lies in the Rydberg blockade – an effect that in practise means that the two photons push and pull each other through the cloud, because the first photon must move forward before the second can excite any nearby atoms.

The new matter is drawing many comparisons to the ‘lightsabers’ of Star Wars fame, but what are the practical applications of the new discovery?

Though commercialisation may be a metaphorical light-year away, it seems that quantum computing may benefit most from the discovery, as well as power dissipation applications in conventional computer chips.

However, the researchers have intimated it is possible that one day, entire crystal structures could be composed of light molecules created in this way. So the idea of a true lightsaber may not be too far, far away after all.

"It's not an in-apt analogy to compare this to light sabers" - Mikhail Lukin


Original source: Harvard University

G.P. Thomas

Written by

G.P. Thomas

Gary graduated from the University of Manchester with a first-class honours degree in Geochemistry and a Masters in Earth Sciences. After working in the Australian mining industry, Gary decided to hang up his geology boots and turn his hand to writing. When he isn't developing topical and informative content, Gary can usually be found playing his beloved guitar, or watching Aston Villa FC snatch defeat from the jaws of victory.


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