Abstract

We propose an original quantum memory protocol. It belongs to the class of rephasing processes and is closely related to two-pulse photon echo. It is known that the strong population inversion produced by the rephasing pulse prevents the plain two-pulse photon echo from serving as a quantum memory scheme. Indeed, gain and spontaneous emission generate prohibitive noise. A second π-pulse can be used to simultaneously reverse the atomic phase and bring the atoms back into the ground state. Then a secondary echo is radiated from a non-inverted medium, avoiding contamination by gain and spontaneous emission noise. However, one must kill the primary echo, in order to preserve all the information for the secondary signal. In the present work, spatial phase mismatching is used to silence the standard two-pulse echo. An experimental demonstration is presented.

Highlights

  • The interaction of quantum light with an ensemble of atoms kindled intense research efforts in the past decade

  • Induced transparency (EIT) combined with the DLCZ generation of narrow-band heralded photons led to convincing experimental demonstrations in atomic vapors [1,2,3]

  • One may map the signal spectral components over the inhomogeneous width of the absorption line, according to the paradigm of the well-known photon echo scheme. Solid state materials such as rare-earth ion-doped crystals (REIC) offer a prime alternative to atomic vapors since they combine the absence of motion with a long coherence lifetime and a large inhomogeneous width

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Summary

Introduction

The interaction of quantum light with an ensemble of atoms kindled intense research efforts in the past decade. This practically limits the bandwidth to the megahertz range To break this barrier, one may map the signal spectral components over the inhomogeneous width of the absorption line, according to the paradigm of the well-known photon echo scheme. Either the phase reversal is produced by an external electric or magnetic field (CRIB and GEM) or rephasing just results from the initial preparation of the inhomogeneously broadened distribution (AFC). Those techniques have proved very successful in terms of efficiency [15, 19], multi-mode capacity [20, 21] and quantum fidelity [22, 23].

Rephasing in the ground state with silenced primary echo
Optimizing the rephasing step
Experimental
Findings
Conclusion

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