Complete Reconstruction of the Quantum State of a Single-Photon Wave Packet Absorbed by a Doppler-Broadened Transition

Towards an efficient atomic frequency comb quantum memory

“…In the absence of dephasing backward recall can reach 100% efficiency by cancelation of the re-absorption, as discussed in Refs. [13,31,15,32,18] …”

“…REICs are characterized by large optical inhomogeneous broadening which enables storage and recall of coherent information by manipulating and controlling the inhomogeneous dephas-ing using echo techniques. Although traditional photon echoes cannot readily be used in the single-photon regime due to spontaneous-emission noise induced by the π-pulse [12], photon echo techniques avoiding this noise have been proposed; controlled reversible inhomogeneous broadening (CRIB) [13,14,15,16,17] and more recently atomic frequency combs (AFC) [18]. The AFC protocol may offer a breakthrough for the practical construction of quantum repeaters capable of achieving sufficient entanglement distribution rate, since the number of modes that can be stored in an AFC QM is independent of the memory material absorption depth.…”

Control of Photon Storage Time in Photon Echoes using a Deshelving Process

“…If the echo propagation direction can be reversed to trace exactly along the data path, then no echo signals from the excited atoms interact with any nonexcited atoms due to the backward propagation scheme (Moiseev & Kroll, 2001). This idea has been experimentally demonstrated in 2009, where the echo enhancement factor even in an optically dilute medium is 15 times (Ham, 2009b).…”

“…Compared with optical coherence, spin coherence is much more robust, roughly ten times longer than the optical counterpart (Ham et al, 1997). Thus, if the optical coherence can be transferred into spin ensembles, longer storage time can be obtained (Moiseev & Kroll, 2001;Moiseev et al, 2003). In 1998, spin coherence excitation using temporally separated Raman optical pulses was investigated, where optical coherence between the optical pulses forming a Raman pulse plays a major role (Ham et al, 1998).…”

“…Since the first observation of coherent retrieval of a stored optical pulse in a Bose Einstein condensate using slow light (Liu et al, 2001), interest in quantum memories has increased in the last decade (Alexander et al, 2006;Afzelius et al, 2010;Chaneliere et al, 2005. Choi et al, 2008110 Ham, 1998;Ham 2009a;Ham, 2010a;Hedges et al, 2010;Hetet et al, 2008;Hosseini et al, 2009;Julsgaard et al, 2004;Kocharovskaya et al, 2001;Kraus et al, 2006;Liu et al, 2001;Moiseev & Kroll, 2001;Moiseev et al, 2003;Neumann et al, 2009;Nilsson & Kroll, 2005;Sangouard et al, 2007;Turukhin et al, 2002;Van der Wal, et al, 2003). Because temporal multimode storage capability is required for the quantum repeaters, a photon echo-type protocol has emerged as a best candidate.…”