Rephasing processes and quantum memory for light: reversibility issues and how to fix them

Abstract

Time reversibility is absent from some recently proposed quantum memory protocols such as Absorption Frequency Comb (AFC). Focusing on AFC memory, we show that quantum efficiency and fidelity are reduced dramatically, as a consequence of non-reversibility, when the spectral width of the incoming signal approaches the memory bandwidth. Non-reversibility is revealed through spectral dispersion, giving rise to phase mismatching. We propose a modified AFC scheme that restores reversibility. This way, signals can be retrieved with excellent efficiency over the entire memory bandwidth. This study could be extended to other quantum memory rephasing schemes in inhomogeneously broadened absorbing media.

8 pages, 6 figures, was presented in 20th International Laser Physics Workshop (LPHYS'11), July 11-15, 2011, Sarajevo, Bosnia and Herzegovina

References in corpus (3)

• Multimode Memories in Atomic Ensembles
• Highly multimode memory in a crystal
• Photon echoes generated by reversing magnetic field gradients in a rubidium vapour

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• Optimal control of non-Markovian dynamics in a single-mode cavity strongly coupled to an inhomogeneously broadened spin ensemble
• Provable Optimality of the Square-Tooth Atomic Frequency Comb Quantum Memory
• Optimal conditions and the dynamics of quantum memory for spatial frequency grating resonators