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Quantum information processing with atoms and photons


Quantum information processors exploit the quantum features of superposition and entanglement for applications not possible in classical devices, offering the potential for significant improvements in the communication and processing of information. Experimental realization of large-scale quantum information processors remains a long-term vision, as the required nearly pure quantum behaviour is observed only in exotic hardware such as individual laser-cooled atoms and isolated photons. But recent theoretical and experimental advances suggest that cold atoms and individual photons may lead the way towards bigger and better quantum information processors, effectively building mesoscopic versions of 'Schrödinger's cat' from the bottom up.

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Figure 1: Optical parametric down-conversion.
Figure 2: A crystal of five atomic beryllium ions (small white dots at centre) confined in a radio-frequency ion trap.
Figure 3: Schematic of an optical lattice.
Figure 4: Optical lattice potentials.
Figure 5: Scheme for a scalable ion trap and optical-lattice quantum computer.
Figure 6: Atom–photon quantum network.
Figure 7: Single-atom cavity-QED experiment.
Figure 8: Pair of rubidium vapour cells used for storage and entanglement.


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This work is supported by the US National Security Agency and Advanced Research and Development Activity under an Army Research Office contract, and by the National Science Foundation ITR programme.

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Correspondence to C. Monroe.

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Monroe, C. Quantum information processing with atoms and photons. Nature 416, 238–246 (2002).

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