[QIP-Sem] MIT Quantum Information Processing Seminar Announcement

[QIP-Sem Mailing List]

This week's MIT QIP seminar will take place on 
Monday, Nov. 29 at 16:00 in 4-237, and features:


Quantum Information Processing with Trapped Ca+ Ions

by Prof. Rainer Blatt <Rainer.Blatt at uibk.ac.at>

Institut für Experimentalphysik, Universität 
Innsbruck, Technikerstraße 25, A-6020 Innsbruck, 
Austria,
and
Institut für Quantenoptik und Quanteninformation, 
Österreichische Akademie der Wissenschaften, 
Technikerstraße 25, A-6020 Innsbruck, Austria.

ABSTRACT

Trapped strings of cold ions provide an ideal 
system for quantum information processing. The 
quantum information can be stored in individual 
ions and these qubits can be individually 
prepared, the corresponding quantum states can be 
manipulated and measured with nearly 100% 
detection efficiency. With a small ion-trap 
quantum computer based on two and three trapped 
Ca+ ions as qubits we have generated in a 
pre-programmed way genuine quantum states. In 
particular, entangled states of two particles, 
i.e. Bell states [1], and of three particles, 
i.e. GHZ and W states [2], were generated using 
an algorithmic procedure and their decoherence 
was investigated. These states are of particular 
interest for the implementation of a three-ion 
quantum register: we have demonstrated selective 
read-out of single qubits (while protecting the 
other qubits) and manipulation of single qubits 
of the register conditioned on the read-out 
results. The generated states have been measured 
experimentally using a technique known as state 
tomography allowing the population and phase of 
the quantum system to be mapped. Moreover, 
quantum teleportation with trapped ions was 
implemented [3] and can be used as resource for 
the transfer of quantum information as well as 
for quantum information processing.

[1] C. F. Roos, G. P.T. Lancaster, M. Riebe, H. 
Häffner,W. Hänsel, S. Gulde, C. Becher, J. 
Eschner, F. Schmidt-Kaler, and R. Blatt, Phys. 
Rev. Lett. 92, 220402 (2004).
[2] C. F. Roos, M. Riebe, H. Häffner, W. Hänsel, 
J. Benhelm, G. P. T. Lancaster, C. Becher, F. 
Schmidt-Kaler, and R. Blatt, Science 304, 1478 
(2004).
[3] M. Riebe, H. Häffner, C. F. Roos, W. Hänsel, 
J. Benhelm, G. P. T. Lancaster, T. W. Körber, C. 
Becher, F. Schmidt-Kaler, D. F. V. James, R. 
Blatt, Nature 429, 734 (2004).


Next week's feature: Robert Schoelkopf from Yale 
Univ. will speak on "Circuit Quantum 
Electrodynamics: Doing Quantum Optics with 
Superconductors".
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