Splitting Pairs

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Science  02 Nov 2012:
Vol. 338, Issue 6107, pp. 583
DOI: 10.1126/science.338.6107.583-a

Entanglement is a property of quantum systems whereby correlations exist between the entangled particles, so that measuring the state of one particle instantaneously reveals that of the other. Such quantum-mechanical correlations are a powerful resource for applications in quantum information processing and secure communication. Although much work has focused on the generation and manipulation of entangled photons, the condensed-matter version in the form of superconducting Cooper pairs of electrons offers the potential of fabricating entangled electronic circuits. However, extracting and then splitting the Cooper pairs has been experimentally challenging, with competing processes giving rise to impractically low efficiencies. Schindele et al. developed a carbon nanotube–based device that can be used to extract the Cooper pairs from a superconductor and then split and store them on two separate quantum dots defined within the nanotube. The experiments revealed splitting efficiencies up to 90%, sufficient for practical applications in quantum electronic circuits.

Phys. Rev. Lett. 109, 157002 (2012).

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