Towards an eficient atomic frequency comb quantum memory

Abstract

We present an efficient photon-echo experiment based on atomic frequency combs [Phys. Rev. A 79, 052329 (2009)]. Echoes containing an energy of up to 35% of that of the input pulse are observed in a Pr 3+ -doped Y 2 SiO 5 crystal. This material allows for the precise spectral holeburning needed to make a sharp and highly absorbing comb structure. We compare our results with a simple theoretical model with satisfactory agreement. Our results show that atomic frequency combs has the potential for high-efficiency storage of single photons as required in future long-distance communication based on quantum repeaters.

Mapping multiple photonic qubits into and out of one solid-state atomic ensemble

“…[20] we show theoretically that F =10 induces a negligible loss, which in combination with a high optical depth d makes the AFC scheme very efficient. High-efficiency mapping using high-finesse combs have been shown experimentally [27,29]. These experiments and the present work stores light for a pre-determined time given by 1/∆.…”

“…The efficiency for single-mode storage is currently lower than has been achieved in the best-performance single-mode memories, e.g. [13,16,19,27,29]. But as explained later our interface compares very favorably to these experiments in terms of potential multimode storage efficiency.…”

“…The next grand challenge is to combine multimode storage, high efficiency [29] and on-demand read out [28] in one experiment. The immediate efforts will most probably by devoted to praseodymium and europium-doped Y 2 SiO 5 crystals, where the ground state manifold has the necessary number of spin levels (three levels) for implementing the on-demand readout.…”

“…Using this method we recently demonstrated [21] that a weak coherent state |α L with mean photon number n = |α| 2 < 1, can be coherently and reversibly mapped onto a YVO 4 crystal doped with neodymium ions. Later experiments [27][28][29] in other RE-doped materials have improved the overall storage efficiency (35%) and storage time (20µs). Yet, in these experiments at most 4 modes have actually been stored at the single photon level, thus the predicted [20,26] high multimode capacity has yet to be shown experimentally.…”

Quantum Memories. A Review based on the European Integrated Project "Qubit Applications (QAP)"

“…The first protocol is based on the controlled and reversible inhomogeneous broadening (CRIB) [50,51,52,53,54,55,56,57,58] of a single absorption line (for a recent review see [8]). The second protocol is based on the reversible absorption by a periodic structure of narrow absorption peaks, a so called atomic frequency comb (AFC) [59,60,61,62,63]. Potential areas of application for this type of quantum memories are for long-distance quantum communication (quantum repeaters) and the realization of quasi-deterministic singlephoton sources.…”