Probing Quantum Memories

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Science  06 Apr 2007:
Vol. 316, Issue 5821, pp. 19
DOI: 10.1126/science.316.5821.19b

Can't quite place a name to the face, or associate a singer with a song? You know, or at least hope, that the information lies intact somewhere in your head, needing only the correct memory trick or stimulus to retrieve it. For quantum communications, where information is transmitted along quantum channels and stored in quantum memories, it is necessary that the stored information be robust and retrievable. However, quantum memories are known to decay because of decoherence, and physicists therefore have to develop their own set of tricks to probe and measure how reliable these memories are. Staudt et al. look at quantum information stored in an optical memory, where the information is encoded in the coherent transfer of the phase and amplitudes of light pulses onto a suitable solid-state medium. They use a photon-echo technique whereby a sequence of pulses initializes the memory cell, encodes the data onto it, and uses a read pulse to generate a stimulated echo pulse which replicates the stored information. The advantage of this scheme is that, though memories may be lost, if they are recalled they remain undistorted. — ISO

Phys. Rev. Lett. 98, 113601 (2007).

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