In Physical Review X, which we get for the “Find Schroedinger’s cat puzzle”, Princeton University electrical engineers have locked individual photons together so that they become like a solid object.
Dr. Andrew Houck, an associate professor of electrical engineering, said that it was something that we have never seen before and a new behaviour for light.
Basically they made an “artificial atom” from 100 billion atoms engineered to act like a single unit. They then brought this close to a superconducting wire carrying photons. The photons became entangled so that properties passed between the “atom” and the photons in the wire. The photons started to behave like atoms, correlating with each other to produce a single oscillating system.
What was weird was that the photons could be in two states at once – a bit like a US murderer with a good alibi.
Dr. Darius Sadri said the team had set up a situation where light effectively behaves like a particle in the sense that two photons can interact very strongly
“In one mode of operation, light sloshes back and forth like a liquid; in the other, it freezes.”
The team is hoping to use the solid light to simulate subatomic behaviour which is jolly useful for statistical mechanics, and often simplify by assuming no interaction between particles and a system at equilibrium.
“The world around us is rarely in equilibrium.” The solidified light offers a chance to observe a subatomic system as it starts to diverge from equilibrium, with potential for a basic understanding of how these systems operate.”