Hannover 2010 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 25: Quantum Information: Quantum Communication I
Q 25.2: Talk
Wednesday, March 10, 2010, 10:45–11:00, E 214
Coherent optical memory with GHz bandwidth — •Klaus Reim1, Joshua Nunn1, Virginia Lorenz2, Ben Sussman3, Ka Lee1, Nathan Langford1, Dieter Jaksch1, and Ian Walmsley1 — 1Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK — 2Department of Physics, University of Delaware, Newark, DE 19716, USA — 3National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
Quantum memories, capable of controllably storing and releasing a light pulse, are a crucial component for quantum computers and quantum communications. So far, quantum memories --- either ensemble based or single absorbers --- have operated with bandwidths of kHz or MHz. Robust, higher bandwidth (faster) quantum memories operating with very short laser pulses are a prerequisite for reliable and broadband quantum technology devices that allow for high-speed quantum processing and high data transfer rates in completely secure quantum networks. Here we report the coherent storage and retrieval of sub-nanosecond low intensity light pulses with spectral bandwidths exceeding 1 GHz in cesium vapor. The memory interaction takes place via a far off-resonant two-photon transition in which the memory bandwidth is dynamically generated by the strong control field. This makes the memory robust to environmental noise and allows an increase of speed by a factor of almost 1000 compared to existing quantum memories. The memory works with a total efficiency of 15 % and its coherence is demonstrated by directly interfering the stored and retrieved pulses.