Bulletin of the American Physical Society
39th Annual Meeting of the APS Division of Atomic, Molecular, and Optical Physics
Volume 53, Number 7
Tuesday–Saturday, May 27–31, 2008; State College, Pennsylvania
Session O2: Optical Quantum Memory (Co-Sponsored by GQI) |
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Chair: Barry Sanders, University of Calgary Room: Kern Building 112 |
Friday, May 30, 2008 8:00AM - 8:36AM |
O2.00001: Quantum state transfer from light to an atomic ensemble at room temperature Invited Speaker: The dispersive interaction of a light beam with an atomic ensemble of 10$^{12}$ Cesium atoms at room temperature constitutes an atom light interface that opens up possibilities for a large variety of experiments interesting for quantum information processing. Here, we describe different options for the transfer of the quantum mechanical state of a light pulse to the atoms, overcoming the classical limitations. The first experimental demonstration of interspecies teleportation - between an atomic and a photonic object - was realized in this setup [1]. The achieved fidelity of 0.56 can be improved by the usage of squeezed light and a more adapted feedback scheme. In addition, a direct-mapping-protocol has previously been demonstrated for coherent light states [2]. The obtained fidelity can be increased by preparing the atomic ensemble in a spin squeezed state before starting the protocol. Spin squeezing has been shown in our setting by individual atom spin squeezing, where we utilize the multilevel structure of Cesium, as well as by a QND measurement of one of the atomic spin components via light. For the latter, a squeezed light source - which we are currently integrating into the experiment - can be useful, enabling the production of stronger atomic squeezing. Furthermore, squeezed or entangled light can be mapped to the atomic ensemble, thus extending the faithful quantum mapping to a class of non classical states. The reported work was conducted together with T. Fernholz, K. Jensen and J. F. Sherson in the group of Eugene Polzik. [1] Sherson, et al., Nature 443, 557 [2] Julsgaard, et al., Nature 432, 482 [Preview Abstract] |
Friday, May 30, 2008 8:36AM - 9:12AM |
O2.00002: Quantum Storage in Solid State Atomic Ensembles Invited Speaker: Reversible and coherent mapping of quantum information between light and matter is an important experimental challenge in quantum information science. In particular such quantum memories are necessary for the implementation of quantum repeaters that would extend the range of quantum communication. In recent years, atomic ensembles have proven to be a promising system in order to implement such a task. We will describe our efforts towards the realization of a storage device for single photons in a solid state environment. Our approach uses solid state atomic ensembles implemented with rare-earth ions doped into dielectric crystals. Due to the weak interactions with the crystal environment and to the absence of atomic diffusion, the rare-earth ions can be considered as a frozen gas of atoms. Single photons can in principle be stored and recalled with high efficiency in such a media using a modified photon echo approach based on coherent control of the inhomogeneous broadening of the optical transition [1]. This method lends itself naturally to the storage of multiple temporal modes [2]. Different wavelengths of absorption are available using different rare-earth ions. In particular, Erbium doped solids have an optical transition around 1530 nm, which make them an attractive candidate for a quantum memory at telecommunication wavelengths, which is necessary for some quantum repeater protocols [3]. After an introduction to motivate the need for quantum memories in quantum communication, we will present the physical system and the storage protocol, before reviewing first experimental steps towards the practical realization of quantum memories in Erbium doped materials. [1] M. Nilsson and S. Kr\"{o}ll, Opt. Comm. 247, 393 (2005), B. Kraus et al, Phys. Rev. A 73, 020302 (2006), G.H\'{e}tet et al, Phys. Rev. Lett. 100, 023601 (2008) [2] C. Simon et al, Phys. Rev. Lett. 98, 190503 (2007), M.U.Staudt et al, Phys. Rev. Lett. 99, 173602 (2007) [3] N. Sangouard et al, Phys. Rev. A 76, 050301 (2007) [Preview Abstract] |
Friday, May 30, 2008 9:12AM - 9:48AM |
O2.00003: Storage of squeezed light as a step towards universal quantum memory Invited Speaker: The ``holy grail'' of the quantum optical memory research is a system that would allow high fidelity storage and retrieval of an arbitrary optical state. We present a functioning testbed for such a system, which brings together the preparation of the quantum state, the memory cell, and full characterization of both the input and the retrieved state in a single apparatus. As demonstration of its capabilities, we report high-fidelity storage and retrieval of the squeezed vacuum state using electromagnetically-induced transparency in atomic rubidium vapor. [Preview Abstract] |
Friday, May 30, 2008 9:48AM - 10:24AM |
O2.00004: Quantum Memory in Solids Invited Speaker: Quantum memories are likely to be critical components in any future long range quantum communication network. A method is described for storing light that operates by controlling the local group velocity of light in a crystal, using an applied electric field gradient to Stark shift an optical transition. Unlike other proposals for quantum memories no optical control pulses are required greatly simplifying the operation of the memory and improving its signal to noise. It is shown that the technique has the potential to operate with near 100{\%} efficiency with little excess noise, making it suitable as a quantum memory. Preliminary experimental results will be presented demonstrating efficiencies up to 45{\%}. These experiments utilized the $^{3}$H$_{4} \quad \Leftrightarrow \quad ^{1}$D$_{2}$ optical transition (605.7 nm) in a 4 mm long crystal of Pr$^{3+}$:Y$_{2}$SiO$_{5}$ cooled to liquid helium temperatures. The experiments are well described by Maxwell-Bloch simulations and such simulations suggest efficiencies much closer to unity should be possible with only modest improvements to the experiment. This work was carried out in collaboration with G. Hetet, J. J. Longdell, A. L. Alexander, P. K. Lam and M. P. Hedges. [Preview Abstract] |
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