Teleportation spin state

A proposal for spin state teleportation was given in Ref. [Duan 2000 (d)]. Three atomic samples are needed as shown in Fig. 3 (a). Adjacent samples are oriented oppositely along the rc-axis so that both collective measurements on cells 1 and 2 and on cells 1 and 3 will be regular entangling interactions as... 

Approximate versions of the translational EPR state, wherein the -function correlations are replaced by finite-width (Gaussian) distributions, have been shown to characterize the quadratures of the two optical-field outputs of parametric down-conversion, or of a fiber interferometer with Kerr nonlinearity. Such states allow for various schemes of continuous-variable quantum information processing such as quantum teleportation [Braunstein 1998 (b) Furu-sawa 1998] or quantum cryptography [Silberhorn 2002], A similar state has also been predicted and realized using collective spins of large atomic samples [Polzik 1999 Julsgaard 2001]. It has been shown that if suitable interaction schemes can be realized, continuous-variable quantum states of the original EPR type could even serve for quantum computation. 

The recently realized feat of teleportation, if only of the spin of a single photon, bodes well for future quantum computation (Zeilinger 1997). The point here is not the transfer of matter, but the safe and speedy distribution of quantum states through the volatile environment of a quantum computer. 

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