Gas memory could send spooky messages the full distance

By | December 18, 2008

Quantum entanglement, which Einstein dubbed “spooky action at a distance”, would be the perfect way to communicate data – if technical hurdles could be overcome.

The method involves linking the quantum properties of two objects such that a change to one is instantly reflected in the other – offering a whole new way to transmit information from opposite sides of the globe.

Entanglement has already been exploited as a way to securely share pass phrases for secret communications, but only over distances of less than 200 kilometres. The inability of the gas-based quantum computer memory used to hold onto information for more than a fraction of a second is to blame.

Now a way to have that memory store quantum information for longer opens up the possibility of entangled communication over 1000 kilometres. …

Jenkins and colleagues have now succeeded in creating quantum memories that last for 7.2 microseconds – more than two orders of magnitude longer than previously reported, and time enough to transmit quantum information over 1000 kilometres.

While qubits made in other ways can hold memories for longer, they struggle to transfer them to photons.

The team’s qubits are stored in gas atoms, encoded into a magnetic property known as “spin”. The key to lengthening the attention span of gas qubits is to shield them from magnetic fields that can distort their spin and dissolve the stored state. … – ns

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