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The big takeaway from their research is that photons, which normally don't interact with one another, can be forced to bunch into pairs or triplets when they're passed through a hyper-cooled cloud of rubidium atoms, where the photons bounce from atom to atom like pinballs. These photons temporarily form a "polaritron," a hybrid between a photon and an atom, when passing by the rubidium atoms.
When two photons join with the same atom, they can become tethered together and break away from the atom with their bond still intact, forming tiny groups of photons that "remember" the process that formed them: according to co-author Sergio Cantu, "When photons go through the medium, anything that happens in the medium, they 'remember' when they get out."
This means scientists can create "novel quantum states of light and quantum entanglement on demand." Einstein's least-favorite physics phenomenon (he called it "spooky action at a distance"), quantum entanglement occurs when two particles become linked, so that when one changes, the other does, too.
Even if the particles are separated and placed extremely far apart, you can always know the state of both particles by looking at only one, and even "send" messages by changing the state of one of them.
If you assemble enough of these entangled particles, you can start to encode data by using them like bits in a normal computer. This is where the quantum computing angle comes in-with entangled photons, data could be transmitted between the particles almost instantaneously.
So, to sum up: Quantum computers of the future may operate using entangled particles of light.
Even seemingly intractable optimization problems may be solved in seconds using this type of computing, while modern supercomputers (operating on lame, regular circuits) might take hundreds of years. No wonder Google is interested in gaining "quantum supremacy."
