Tuesday, January 18, 2011

Ethereal Quantum State Stored In Solid Crystal

ETHEREAL quantum entanglement has been captured in solid crystals, showing that it is more robust than once assumed. These entanglement traps could make quantum computing and communication more practical.

In the quantum world, two or more objects can be entangled so that measuring one affects the outcome of measuring the others, no matter how far apart the objects are. This property is central to quantum cryptography, where it allows two people to be sure a secret key they shared was not intercepted, and to quantum computing, as entangled bits occupy a superposition of two or more states at once and so can be used to solve some problems much faster than conventional computers.

A missing element is memory, which is needed to do complex calculations and to transmit quantum states over large distances. "Photons travel at the speed of light, which is bad for storage," says Wolfgang Tittel at the University of Calgary in Alberta, Canada. Chilled clouds of atoms can act as quantum memory, but this requires bulky equipment and trained physicists.



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