
Star Trek
Researchers at Geneva University have developed a “quantum memory“, capturing a single particle of light (a photon) in a crystal and then reproducing and retransmitting it.
The findings, published in last week’s edition of the academic journal Nature, could translate into important applications in the field of quantum cryptography, guaranteeing highly secure communication, and quantum computers that will run billions of times faster than today’s machines.
Quantum teleportation is the transmission of key properties from one particle to another without a physical link. It relies on an aspect of physics known as “entanglement“, whereby the properties of two particles can be tied together even when they are far apart. Albert Einstein called it “spooky action at a distance”.
The Geneva-based team managed to stop a light particle in a tiny one-millimetre crystal cooled to a temperature of minus 270 degrees Celsius.
The photon’s properties were then passed on to some ten million atoms inside the crystal, explained Professor Nicolas Gisin, head of the Group of Applied Physics at Geneva University. He said this produced an echo, like in a cave, re-emitting the photon with the same characteristics.
“We physicists have played with photons for years. It has always been a fascinating challenge to try to stop a photon and hold it for a while – to stop it without destroying it and release it with the same quantum states,” he told swissinfo (source).
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