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--></style><title>MIT Quantum Information Processing Seminar
Announcement</title></head><body>
<div>Next week's MIT QIP seminar will take place on Monday, Nov. 8 at
16:00 in 4-237, and features:</div>
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<div align="center"><font size="+2"><b>Progress Towards Quantum
Communication over Long Distances</b></font></div>
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<div align="center"><font size="+1"><i>by</i> Mikhail Lukin
(<i>Harvard University Physics Dept.</i>)</font></div>
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<div align="center"><u>ABSTRACT</u></div>
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<blockquote>Quantum communication holds promise for transmitting
secure messages via quantum cryptography, and for communicating
quantum information. However, extending quantum communication
techniques to long distances represents a conceptual and technological
challenge: on the one hand photon losses fundamentally limit the range
of direct communication, on the other hand quantum signals
cannot be amplified without adding noise. The so-called
quantum repeater techniques provide a potential solution to this
problem. Implementation of these techniques requires coherent
light-matter interface including quantum memory nodes for photon
state storage and the means for generation and purifying
quantum entangled states. This talk will describe our
progress toward developing the new tools and techniques required
for constructing quantum repeaters. Two specific approaches
based on atomic and solid state systems will be
described.</blockquote>
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