Quantum memory speeds up | University of Oxford
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Quantum memory speeds up

Pete Wilton

A team, including Oxford University scientists, has achieved a new record for storing and retrieving data from an optical quantum memory, our friends PhysOrg.com report.

The researchers achieved a data rate in excess of 1GHz, 100 times what is possible with existing quantum memories, they explain in Nature Photonics. Such a speedy memory would be a key component of any future quantum computing or communications device.

The result was achieved by firing pulses of thousands of photons encoded with data into a cesium vapor cell. The vapor turns the pulses into a spin wave, and the information can be retrieved by a read pulse that converts the spin wave back into an optical signal that is picked up by a detector.

Ian Walmsley, of Oxford University's Department of Physics, told PhysOrg's Lisa Zyga: 'There are a few steps that are required [to achieve high bandwidth], but the main approach is to use atoms with a higher energy storage state, and to apply more sophisticated control pulse methods.'

'Our plans are to demonstrate the operation of the memory at the quantum limit, using an external source of nonclassical light.'

The team note that the bandwidth was limited only by the response time of the detector, so in theory the quantum memory could be capable of even larger bandwidths. Their method, based on a Raman interaction, could be applied to other storage media (such as cold gases and solid state).

Ian adds: 'Challenges for the future in general are to increase the number of bits the memory can store and the readout efficiency of the memories to the point when they can be used in applications such as quantum communications links.'