Epitaxially grown quantum dots (QDs) are promising sources of non-classicalstates of light such as single photons and entangled photons. However, in orderfor them to be used as a resource for long-distance quantum communication,distributed quantum computation, or linear optics quantum computing, thesephotons must be coupled efficiently to long-lived quantum memories as part of aquantum repeater network. Here, we theoretically examine the prospects forefficient storage and retrieval of a QD-generated single photon with a 1 nslifetime in a multi-level atomic system. We calculate using an experimentallydemonstrated optical depth of 150 that the storage (total) efficiency canexceed 46% (28%) in a dense, ultracold ensemble of $^{87}$Rb atoms.Furthermore, we find that the optimal control pulse required for storage andretrieval can be obtained using a diode laser and an electro-optic modulatorrather than a mode-locked, pulsed laser source. Increasing the optical depth,for example by using Bose-condensed ensembles or an optical cavity, canincrease the efficiencies to near unity. Aside from enabling a high-speedquantum network based on QDs, such an efficient optical interface between anatomic ensemble and a QD can also lead to entanglement between collectivespin-wave excitations of atoms and the spin of an electron or hole confined inthe QD.
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