Abstract
An outstanding goal in quantum information science is the faithful mapping of quantum information between a stable quantum memory and a reliable quantum communication channel1. This would allow, for example, quantum communication over remote distances2, quantum teleportation3 of matter and distributed quantum computing over a âquantum internetâ. Because quantum states cannot in general be copied, quantum information can only be distributed in these and other applications by entangling the quantum memory with the communication channel. Here we report quantum entanglement between an ideal quantum memoryârepresented by a single trapped 111Cd+ ionâand an ideal quantum communication channel, provided by a single photon that is emitted spontaneously from the ion. Appropriate coincidence measurements between the quantum states of the photon polarization and the trapped ion memory are used to verify their entanglement directly. Our direct observation of entanglement between stationary and âflyingâ qubits4 is accomplished without using cavity quantum electrodynamic techniques5,6,7 or prepared non-classical light sources3. We envision that this source of entanglement may be used for a variety of quantum communication protocols2,8 and for seeding large-scale entangled states of trapped ion qubits for scalable quantum computing9.
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References
DiVincenzo, D. The physical implementation of quantum computation. Fortschr. Phys. 48, 771â783 (2000)
Duan, L.-M., Lukin, M., Cirac, J. I. & Zoller, P. Long-distance quantum communication with atomic ensembles and linear optics. Nature 414, 413â418 (2001)
Bouwmeester, D., Ekert, A. & Zeilinger, A. (eds) Quantum Cryptography, Quantum Teleportation, Quantum Computation (Springer, Springer, 2000)
Gheri, K., Ellinger, K., Pellizzari, T. & Zoller, P. Photon-wavepackets as flying quantum bits. Fortschr. Phys. 46, 401â415 (1998)
Haroche, S., Raimond, J. M. & Brune, M. in Experimental Quantum Computation and Information (eds de Martini, F. & Brune, M.) 3â36 (Proc. Int. School of Physics Enrico Fermi, course CXLVIII, IOS Press, Amsterdam, 2002)
Kuhn, A. & Rempe, G. in Experimental Quantum Computation and Information (eds de Martini, F. & Monroe, C.) 37â66 (Proc. Int. School of Physics Enrico Fermi, course CXLVIII, IOS Press, Amsterdam, 2002)
McKeever, J. et al. State-insensitive cooling and trapping of single atoms in an optical cavity. Phys. Rev. Lett. 90, 133602 (2003)
Briegel, H.-J., Duer, W., Cirac, J. I. & Zoller, P. Quantum repeaters: the role of imperfect local operations in quantum communication. Phys. Rev. Lett. 81, 5932â5935 (1998)
Duan, L.-M., Blinov, B. B., Moehring, D. L. & Monroe, C. Scalable trapped ion quantum computation with a probabilistic ion-photon mapping. Preprint at ãhttp://www.arxiv.org/quant-ph/0401020ã (2004)
Freedman, S. J. & Clauser, J. F. Experimental test of local hidden variables theories. Phys. Rev. Lett. 28, 938â941 (1972)
Aspect, A., Grangier, P. & Roger, G. Experimental realization of Einstein-Podolsky-Rosen-Bohm Gedanken experiment: a new violation of Bell's inequalities. Phys. Rev. Lett. 49, 91â94 (1982)
Eichmann, U. et al. Young's interference experiment with light scattered from two atoms. Phys. Rev. Lett. 70, 2359â2362 (1993)
DeVoe, R. G. & Brewer, R. G. Observation of superradiant and subradiant spontaneous emission of two trapped ions. Phys. Rev. Lett. 76, 2049â2052 (1996)
Kuzmich, A., Mandel, L. & Bigelow, N. Generation of spin squeezing via continuous quantum nondemolition measurement. Phys. Rev. Lett. 85, 1594â1597 (2000)
Julsgaard, B., Kozhekin, A. & Polzik, E. Experimental long-lived entanglement of two macroscopic objects. Nature 413, 400â403 (2001)
Kuzmich, A. et al. Generation of nonclassical photon pairs for scalable quantum communication with atomic ensembles. Nature 423, 731â734 (2003)
van der Wal, C. H. et al. Atomic memory for correlated photon states. Science 301, 196â200 (2003)
Wineland, D. J. et al. Experimental issues in coherent quantum manipulation of trapped atomic ions. NIST J. Res 103, 259â328 (1998)
Cirac, J. I. & Zoller, P. Quantum computations with cold trapped ions. Phys. Rev. Lett. 74, 4091â4094 (1995)
Sørensen, A. & Mølmer, K. Quantum computation with ions in thermal motion. Phys. Rev. Lett. 82, 1971â1975 (1999)
GarcÃa-Ripoll, J. J., Zoller, P. & Cirac, J. I. Speed optimized two-qubit gates with laser coherent control techniques for ion trap quantum computing. Phys. Rev. Lett. 91, 157901 (2003)
Blatt, R. & Zoller, P. Quantum jumps in atomic systems. Eur. J. Phys. 9, 250â256 (1988)
BadziÄg, P., Horodecki, M., Horodecki, P. & Horodecki, R. Local environment can enhance fidelity of quantum teleportation. Phys. Rev. A 62, 012311 (2000)
Sackett, C. A. et al. Experimental entanglement of four particles. Nature 404, 256â259 (2000)
Guthorlein, G., Keller, M., Hayasaka, H., Lange, W. & Walther, H. A single ion as a nanoscopic probe of an optical field. Nature 414, 49â51 (2001)
Mundt, A. B. et al. Coupling a single atomic quantum bit to a high finesse optical cavity. Phys. Rev. Lett. 89, 103001 (2002)
Duan, L.-M. & Kimble, J. Efficient engineering of multiatom entanglement through single-photon detections. Phys. Rev. Lett. 90, 253601 (2003)
Simon, C. & Irvine, W. Robust long-distance entanglement and a loophole-free Bell test with ions and photons. Phys. Rev. Lett. 91, 110405 (2003)
Cabrillo, C., Cirac, J. I., Garcia-Fernandez, P. & Zoller, P. Creation of entangled states of distant atoms by interference. Phys. Rev. A 59, 1025â1033 (1999)
Bennett, C. H., DiVincenzo, D. P., Smolin, J. A. & Wootters, W. K. Mixed-state entanglement and quantum error correction. Phys. Rev. A 54, 3824â3851 (1996)
Acknowledgements
We acknowledge discussions with M. Madsen, P. Haljan, M. Acton and D. Wineland, and thank R. Miller for assistance in building the trap apparatus. This work was supported by the National Security Agency, the Advanced Research and Development Activity, under Army Research Office contract, and the National Science Foundation Information Technology Research Division.
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Blinov, B., Moehring, D., Duan, L . et al. Observation of entanglement between a single trapped atom and a single photon. Nature 428, 153â157 (2004). https://doi.org/10.1038/nature02377
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DOI: https://doi.org/10.1038/nature02377