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Reminder</title></head><body>
<div>This week's MIT QIP seminar will take place on Monday, April 5th
at 16:00 in 4-237, and features:</div>
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<hr>
<div align="center"><font size="+2"><b>Localizable Entanglement and
Valence Bond States</b></font></div>
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<div align="center"><font size="+1"><i>by</i> Ignacio Cirac (<i>Max
Planck Institute fuer Quantumoptik, Garching,
Germany</i>)</font></div>
<div align="center"><br></div>
<div align="center"><u>ABSTRACT</u></div>
<div><br></div>
<blockquote>Much of the current effort in Quantum Information Theory
is devoted to the description and quantification of the entanglement
contained in quantum states, since this intriguing property of Quantum
Mechanics is the basic resource of most of the applications in this
field, including quantum communication and computation. In this talk I
will introduce a new notion of entanglement which captures the idea of
how this property can be localized in small subsystems by performing
measurement in the rest of the system. I will also show how this
notion allows to detect hidden orders in spin systems at zero
temperature, and how it behaves in quantum phase transitions. Finally,
I will show how these ideas may help to develop simulation schemes for
spin chains and lattices.</blockquote>
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<hr>
<div>There will also be a special seminar this week on Tuesday, April
6 from 10:00 thru<b> 11:00</b> AM in the Marlar Lounge (37-252)</div>
<div><br></div>
<hr>
<div align="center"><font size="+2"><b>Ion Trapology for Scalable
Quantum Information Processing</b></font></div>
<div align="center"><br></div>
<div align="center"><font size="+1"><i>by</i> David J. Wineland
(<i>Time & Frequency Division</i>, NIST,<i> Boulder</i>
CO)</font></div>
<div align="center"><br></div>
<div align="center"><u>ABSTRACT</u></div>
<div><br></div>
<blockquote>At NIST, by using a few trapped atomic ions, we have been
able to implement the basic one- and two-qubit gate operations
required for quantum information processing [<u>1</u>]. The
challenge is to scale up this system in order to perform large-scale
processing. One way this might be accomplished is to use an
array of ion trap zones, each of which contains a small number of ions
- to facilitate efficient gates. By shuttling ions between
zones, gates between selected ions in the array could be achieved
[<u>2</u>]. By separating ions contained in one trap, moving
them to separate trap zones, and performing subsequent logic
operations, we can now implement the basic steps of this scheme.
However, we now face significant practical problems in how to actually
fabricate the required large trap structures, how to wire up the trap
electrodes and control their potentials, and how to produce and
manipulate the many laser beams that will be needed in such a device.
These and other issues will be discussed.</blockquote>
<div><br></div>
<blockquote>[<u>1</u>] "The physical implementation of quantum
computation", D. P. DiVincenzo, in<i> Scalable Quantum
Computers</i>, ed. by S. L. Braunstein and H. K. Lo (Wiley-VCH,
Berlin, 2001), pp. 1-13.</blockquote>
<blockquote>[<u>2</u>] "Architecture for a large-scale ion-trap
quantum computer", D. Kielpinski, C. Monroe, and D. J.
Wineland,<i> Nature</i><b> 417</b>, 709-711 (2002).</blockquote>
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