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Observation of entanglement between a single trapped atom and a single photon

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 ‘quantum internet’. 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 memory—represented by a single trapped 111Cd+ ion—and 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 ‘flying’ 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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Figure 1: The experimental apparatus.
Figure 2: The experimental procedure (time axis not to scale).
Figure 3: Measured conditional probabilities in the original basis (no atomic or photonic qubit rotation before measurement).
Figure 4: Conditional probabilities after both atomic and photonic qubits are rotated by a polar angle of π/2 in the Bloch sphere.

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References

  1. DiVincenzo, D. The physical implementation of quantum computation. Fortschr. Phys. 48, 771–783 (2000)

    Article  Google Scholar 

  2. Duan, L.-M., Lukin, M., Cirac, J. I. & Zoller, P. Long-distance quantum communication with atomic ensembles and linear optics. Nature 414, 413–418 (2001)

    Article  ADS  CAS  Google Scholar 

  3. Bouwmeester, D., Ekert, A. & Zeilinger, A. (eds) Quantum Cryptography, Quantum Teleportation, Quantum Computation (Springer, Springer, 2000)

  4. Gheri, K., Ellinger, K., Pellizzari, T. & Zoller, P. Photon-wavepackets as flying quantum bits. Fortschr. Phys. 46, 401–415 (1998)

    Article  CAS  Google Scholar 

  5. Haroche, S., Raimond, J. M. & Brune, M. in Experimental Quantum Computation and Information (eds de Martini, F. & Brune, M.) 3–36 (Proc. Int. School of Physics Enrico Fermi, course CXLVIII, IOS Press, Amsterdam, 2002)

    Google Scholar 

  6. Kuhn, A. & Rempe, G. in Experimental Quantum Computation and Information (eds de Martini, F. & Monroe, C.) 37–66 (Proc. Int. School of Physics Enrico Fermi, course CXLVIII, IOS Press, Amsterdam, 2002)

    Google Scholar 

  7. McKeever, J. et al. State-insensitive cooling and trapping of single atoms in an optical cavity. Phys. Rev. Lett. 90, 133602 (2003)

    Article  ADS  CAS  Google Scholar 

  8. 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, 5932–5935 (1998)

    Article  ADS  CAS  Google Scholar 

  9. Duan, L.-M., Blinov, B. B., Moehring, D. L. & Monroe, C. Scalable trapped ion quantum computation with a probabilistic ion-photon mapping. Preprint at 〈http://www.arxiv.org/quant-ph/0401020〉 (2004)

  10. Freedman, S. J. & Clauser, J. F. Experimental test of local hidden variables theories. Phys. Rev. Lett. 28, 938–941 (1972)

    Article  ADS  CAS  Google Scholar 

  11. 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, 91–94 (1982)

    Article  ADS  Google Scholar 

  12. Eichmann, U. et al. Young's interference experiment with light scattered from two atoms. Phys. Rev. Lett. 70, 2359–2362 (1993)

    Article  ADS  CAS  Google Scholar 

  13. DeVoe, R. G. & Brewer, R. G. Observation of superradiant and subradiant spontaneous emission of two trapped ions. Phys. Rev. Lett. 76, 2049–2052 (1996)

    Article  ADS  CAS  Google Scholar 

  14. Kuzmich, A., Mandel, L. & Bigelow, N. Generation of spin squeezing via continuous quantum nondemolition measurement. Phys. Rev. Lett. 85, 1594–1597 (2000)

    Article  ADS  CAS  Google Scholar 

  15. Julsgaard, B., Kozhekin, A. & Polzik, E. Experimental long-lived entanglement of two macroscopic objects. Nature 413, 400–403 (2001)

    Article  ADS  CAS  Google Scholar 

  16. Kuzmich, A. et al. Generation of nonclassical photon pairs for scalable quantum communication with atomic ensembles. Nature 423, 731–734 (2003)

    Article  ADS  CAS  Google Scholar 

  17. van der Wal, C. H. et al. Atomic memory for correlated photon states. Science 301, 196–200 (2003)

    Article  ADS  CAS  Google Scholar 

  18. Wineland, D. J. et al. Experimental issues in coherent quantum manipulation of trapped atomic ions. NIST J. Res 103, 259–328 (1998)

    Article  CAS  Google Scholar 

  19. Cirac, J. I. & Zoller, P. Quantum computations with cold trapped ions. Phys. Rev. Lett. 74, 4091–4094 (1995)

    Article  ADS  CAS  Google Scholar 

  20. Sørensen, A. & Mølmer, K. Quantum computation with ions in thermal motion. Phys. Rev. Lett. 82, 1971–1975 (1999)

    Article  ADS  Google Scholar 

  21. García-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)

    Article  ADS  Google Scholar 

  22. Blatt, R. & Zoller, P. Quantum jumps in atomic systems. Eur. J. Phys. 9, 250–256 (1988)

    Article  CAS  Google Scholar 

  23. Badzięg, P., Horodecki, M., Horodecki, P. & Horodecki, R. Local environment can enhance fidelity of quantum teleportation. Phys. Rev. A 62, 012311 (2000)

    Article  ADS  Google Scholar 

  24. Sackett, C. A. et al. Experimental entanglement of four particles. Nature 404, 256–259 (2000)

    Article  ADS  CAS  Google Scholar 

  25. Guthorlein, G., Keller, M., Hayasaka, H., Lange, W. & Walther, H. A single ion as a nanoscopic probe of an optical field. Nature 414, 49–51 (2001)

    Article  ADS  Google Scholar 

  26. Mundt, A. B. et al. Coupling a single atomic quantum bit to a high finesse optical cavity. Phys. Rev. Lett. 89, 103001 (2002)

    Article  ADS  CAS  Google Scholar 

  27. Duan, L.-M. & Kimble, J. Efficient engineering of multiatom entanglement through single-photon detections. Phys. Rev. Lett. 90, 253601 (2003)

    Article  ADS  Google Scholar 

  28. Simon, C. & Irvine, W. Robust long-distance entanglement and a loophole-free Bell test with ions and photons. Phys. Rev. Lett. 91, 110405 (2003)

    Article  ADS  Google Scholar 

  29. Cabrillo, C., Cirac, J. I., Garcia-Fernandez, P. & Zoller, P. Creation of entangled states of distant atoms by interference. Phys. Rev. A 59, 1025–1033 (1999)

    Article  ADS  CAS  Google Scholar 

  30. Bennett, C. H., DiVincenzo, D. P., Smolin, J. A. & Wootters, W. K. Mixed-state entanglement and quantum error correction. Phys. Rev. A 54, 3824–3851 (1996)

    Article  ADS  MathSciNet  CAS  Google Scholar 

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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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Correspondence to B. B. Blinov.

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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, 153–157 (2004). https://doi.org/10.1038/nature02377

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