Southwest Quantum Information and Technology

Tenth Annual Meeting, February 14-17, 2008
University of New Mexico, Santa Fe, New Mexico


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SESSION 11: Quantum Communication
Session Chair:
08:30-09:15Irina Novikova, The College of William & Mary (invited)
Optimal control of light storage and retrieval

Abstract. Mapping of quantum states between light and matter (light storage) using a dynamic form of electromagnetically induced transparency is a topic of great current interest. We demonstrate experimentally a general approach to obtain the maximum efficiency for the storage and retrieval of light pulses in atomic media by finding optimal temporal profile for a strong control field or a signal wavepacket. The procedure uses time reversal to obtain optimal input signal pulse-shapes. Experimental results in warm Rb vapor are in good agreement with theoretical predictions and demonstrate a substantial improvement of efficiency. These optimization procedures are applicable to a wide range of systems.
09:15-09:45Jim Harrington, Los Alamos National Laboratory
Practical long distance quantum key distribution

Abstract. We implemented a quantum key distribution protocol of phase-encoded BB84 with decoy states in optical fiber, and we achieved secret bits over more than 140 km with high confidence of security against any eavesdropping attack. The protocol included finite statistics effects for decoy state analysis, reconciliation, deskewing, information estimate, and privacy amplification.
09:45-10:15Shellee Dyer, National Institute of Standards and Technology
Ultra-Low Noise Photon Pair Source in Dispersion Shifted Optical Fiber

Abstract. Single photon and photon pair sources are important resources for optical quantum information processing. We demonstrate a fiber-based photon pair source in which the photon pairs are generated through four-wave mixing in dispersion shifted fiber (DSF). Previous demonstrations of photon pair generation in DSF were limited by the strong Raman scattering background in the fiber. By cooling the fiber to 4 K, we demonstrate that we can achieve almost complete suppression of the Raman photons, yielding a coincidence-to-accidental ratio larger than 300, exceeding previous best-case results by a factor of 4.