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Quantum Information and Quantum Control Conference
July 19-23, 2004
The Fields Institute
Toronto, ON, Canada |
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Organizers
Prof.'s Paul Brumer, Daniel Lidar, Hoi-Kwong Lo, and Aephraim Steinberg (University of Toronto)
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Quantum Logics using Four-Photon Entanglement
by
Philip Walther
Institute for Experimental Physics, University of Vienna
The availability of four-photon entanglement allows demonstrating
probabilistic quantum logic gates, such as the controlled-not (cnot)
and sign-shift gate, as well as path-entanglement of up to four photons.
A cnot gate [1] was achieved by using polarization entangled qubits and
polarizing beamsplitters. A similar configuration of the setup for
the cnot-experiment leads to a sophisticated interferometer [2], which
was required for the first experimental observation of the reduced
deBroglie wavelength of a nonlocal four-photon state. One of the central elements in linear optics quantum computing is a
conditional phase shift such that if one photon is present, no phase
shift arises, but if two photons are present, the state achieves the
phase shift of . Most recently such a gate [3] was realized in our
group using only one beamsplitter.
[1] S.Gasparoni, J.-W.Pan, P.Walther, T.Rudolph, A.Zeilinger, Realization of a Photonic CNOT Gate sufficient
for Quantum Computation, accepted for publication in Phys. Rev. Lett.
[2] P.Walther, J.-W.Pan, M.Aspelmeyer, R.Ursin, S.Gasparoni, A.Zeilinger, De Broglie Wavelength of a Nonlocal Four-Photon state, Nature (in press)
[3] K.Sanaka, T.Jennewein, J.-W.Pan, K.Resch, A.Zeilinger, Experimental Nonlinear Sign Shift for Linear Optics Quantum Computation, Phys. Rev. Lett. 92, 017902 (2004)
Date received: April 28, 2004
Copyright © 2004 by the author(s).
The author(s) of this document and the organizers of the conference
have granted their consent to include this abstract in
Atlas Mathematical Conference Abstracts.
Document # cann-66.