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Updated: Jun 14, 2026

Gradient Echo Quantum Memory in Warm Atomic Vapor
Published on: November 11, 2013
Capacities of lossy bosonic memory channels
Cosmo Lupo1, Vittorio Giovannetti, Stefano Mancini
1Dipartimento di Fisica, Università di Camerino, via Madonna delle Carceri 9, I-62032 Camerino, Italy.
Abstract:
We introduce a general model describing correlated noise effects in quantum optical communication via attenuating media. The memory effects account for the environment finite relaxation times, which are unavoidable in any realistic model. The use of a proper set of collective field variables allows us to unravel the memory, showing that the n-fold concatenation of the memory channel is unitarily equivalent to the direct product of n single-mode lossy bosonic channels. We then compute the ultimate (classical and quantum) transmission rates, showing their enhancement with respect to the memoryless case and proving that coherent state encoding is optimal.
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