Broadband waveguide quantum memory for entangled photons

Quantum information processing and communication relies on encoding information into quantum states of physical systems such as photons [1]. Actualizing a quantum interface [2] between light and matter is imperative for construction of a quantum repeater [3], which requires a faithful mapping of quantum entanglement [1] between light and matter. In this work we report the reversible transfer of photon-photon entanglement into entanglement between a photon and a collective atomic excitation in a solid-state thulium-doped lithium niobate waveguide [4] (this transfer was simultaneously done in [5]). References: [1] J.-W. Pan et al. arXiv:0805.2853, 2008. [2] A. I. Lvovsky, B. C. Sanders, & W. Tittel. Nat Photon, 3 (12): 706-714, 2009. [3] N. Sangouard et al. arXiv:0906.2699, 2009. [4] E. Saglamyurek et al. Nature, 469 (7331): 512-515, 2011. [5] C. Clausen et al. Nature, 469 (7331): 508-511, 2011.