Harvard and MIT scientists discover a new state of matter?

 Harvard and MIT scientists discover a new state of matter?

 A group of researchers led by Harvard Physics Professor Mikhail Lukin and Massachusetts Institute of Technology Physics Professor Vladan Vuletic have taken an unexpected step in our knowledge of the nature of light and have succeeded in creating a state of the matter that until a few weeks ago was purely theoretical: photons that behave as if they had mass.

Photons have been described for decades as massless particles that cannot interact with each other. For example, if we cross two laser beams, the respective light beams will pass through each other, they will cross each other.

Light molecules: from traditional lasers to light swords?

The group of researchers from the Harvard-MIT Center for Ultracold Atoms has succeeded in creating a type of medium (which they call extreme) in which photons interact with each other so strongly that they behave as if they had mass, and join together to form molecules .

 

 Lukin has stated that it is not out of place to make an analogy with the lightsabers seen in movies like Star Wars, hitherto pure science fiction. The physics that supposedly is behind what we see in these movies is very similar to what they have achieved: photons, interacting with each other, push, and deflect each other.

The experiment?

 The scientists pumped rubidium atoms into a vacuum chamber creating a cloud that cooled until it almost reached absolute zero. Using very weak laser pulses they fired individual photons into the cloud of atoms. “When the photons enter the cloud, their energy excites the atoms in their path, which causes a strong deceleration in the photons. As the photons move through the cloud, that energy passes from one atom to another and then leaves the cloud with the photon ”, explains Lukin in an article published on the Harvard University website. And he adds: “When the photon leaves the medium, its identity is preserved. The effect is the same as that observed in the refraction of light in a glass of water. Light enters the water, delivers part of its energy to the environment and exists there as light and matter. However, when it comes out, it is still light. The process is the same, only in this case it is a bit more extreme. Light slows down considerably and delivers much more energy than refraction. 

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The scientists pumped rubidium atoms into a vacuum chamber creating a cloud that cooled until it almost reached absolute zero. Using very weak laser pulses they fired individual photons into the cloud of atoms. “When the photons enter the cloud, their energy excites the atoms in their path, which causes a strong deceleration in the photons. As the photons move through the cloud, that energy passes from one atom to another and then leaves the cloud with the photon ”, explains Lukin in an article published on the Harvard University website. And he adds: “When the photon leaves the medium, its identity is preserved. The effect is the same as that observed in the refraction of light in a glass of water. Light enters the water, delivers part of its energy to the environment and exists there as light and matter. However, when it comes out, it is still light. The process is the same, only in this case it is a bit more extreme. Light slows down considerably and delivers much more energy than refraction. "