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Controlled exchange interaction between pairs of neutral atoms in an optical lattice

Abstract

Ultracold atoms trapped by light offer robust quantum coherence and controllability, providing an attractive system for quantum information processing and for the simulation of complex problems in condensed matter physics. Many quantum information processing schemes require the manipulation and deterministic entanglement of individual qubits; this would typically be accomplished using controlled, state-dependent, coherent interactions among qubits. Recent experiments have made progress towards this goal by demonstrating entanglement among an ensemble of atoms1 confined in an optical lattice. Until now, however, there has been no demonstration of a key operation: controlled entanglement between atoms in isolated pairs. Here we use an optical lattice of double-well potentials2,3 to isolate and manipulate arrays of paired 87Rb atoms, inducing controlled entangling interactions within each pair. Our experiment realizes proposals to use controlled exchange coupling4 in a system of neutral atoms5. Although 87Rb atoms have nearly state-independent interactions, when we force two atoms into the same physical location, the wavefunction exchange symmetry of these identical bosons leads to state-dependent dynamics. We observe repeated interchange of spin between atoms occupying different vibrational levels, with a coherence time of more than ten milliseconds. This observation demonstrates the essential component of a neutral atom quantum SWAP gate (which interchanges the state of two qubits). Its ‘half-implementation’, the gate, is entangling, and together with single-qubit rotations it forms a set of universal gates for quantum computation4.

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Figure 1: Experimental sequence.
Figure 2: Qubit state analysis.
Figure 3: Collisional swap dynamics.
Figure 4: Spin-phase coherence during the SWAP operation.

References

  1. Mandel, O. et al. Controlled collisions for multi-particle entanglement of optically trapped atoms. Nature 425, 937–940 (2003)

    ADS  CAS  Article  Google Scholar 

  2. Sebby-Strabley, J., Anderlini, M., Jessen, P. S. & Porto, J. V. Lattice of double wells for manipulating pairs of cold atoms. Phys. Rev. A. 73, 033605 (2006)

    ADS  Article  Google Scholar 

  3. Anderlini, M., Sebby-Strabley, J., Kruse, J., Porto, J. V. & Phillips, W. D. Controlled atom dynamics in a double-well optical lattice. J. Phys. B 39, S199–S210 (2006)

    ADS  CAS  Article  Google Scholar 

  4. Loss, D. & DiVincenzo, D. P. Quantum computation with quantum dots. Phys. Rev. A. 57, 120–126 (1998)

    ADS  CAS  Article  Google Scholar 

  5. Hayes, D., Julienne, P. S. & Deutsch, I. H. Quantum logic via the exchange blockade in ultracold collisions. Phys. Rev. Lett. 98, 070501 (2007)

    ADS  Article  Google Scholar 

  6. Kane, B. E. A silicon-based nuclear spin quantum computer. Nature 393, 133–137 (1998)

    ADS  CAS  Article  Google Scholar 

  7. DiVincenzo, D. P., Bacon, D., Kempe, J., Burkard, G. & Whaley, K. B. Universal quantum computation with the exchange interaction. Nature 408, 339–342 (2000)

    ADS  CAS  Article  Google Scholar 

  8. Duan, L. M., Demler, E. & Lukin, M. D. Controlling spin exchange interactions of ultracold atoms in optical lattices. Phys. Rev. Lett. 91, 090402 (2003)

    ADS  Article  Google Scholar 

  9. Brennen, G. K., Caves, C. M., Jessen, F. S. & Deutsch, I. H. Quantum logic gates in optical lattices. Phys. Rev. Lett. 82, 1060–1063 (1999)

    ADS  CAS  Article  Google Scholar 

  10. Jaksch, D., Briegel, H. J., Cirac, J. I., Gardiner, C. W. & Zoller, P. Entanglement of atoms via cold controlled collisions. Phys. Rev. Lett. 82, 1975–1978 (1999)

    ADS  CAS  Article  Google Scholar 

  11. Jaksch, D. et al. Fast quantum gates for neutral atoms. Phys. Rev. Lett. 85, 2208–2211 (2000)

    ADS  CAS  Article  Google Scholar 

  12. Lee, P. J. et al. Sublattice addressing and spin-dependent motion of atoms in a double-well lattice. Phys. Rev. Lett. (in the press); preprint at <http://arxiv.org/quant-ph/0702039>.

  13. Pethick, C. J. & Smith, H. Bose-Einstein Condensation in Dilute Gases Ch. 5 (Cambridge Univ. Press, Cambridge, UK, 2002)

    Google Scholar 

  14. Greiner, M., Mandel, O., Esslinger, T., Hansch, T. W. & Bloch, I. Quantum phase transition from a superfluid to a Mott insulator in a gas of ultracold atoms. Nature 415, 39–44 (2002)

    ADS  CAS  Article  Google Scholar 

  15. Batrouni, G. G. et al. Mott domains of bosons confined on optical lattices. Phys. Rev. Lett. 89, 117203 (2002)

    ADS  CAS  Article  Google Scholar 

  16. Kastberg, A., Phillips, W. D., Rolston, S. L., Spreeuw, R. J. C. & Jessen, P. S. Adiabatic cooling of cesium to 700-nK in an optical lattice. Phys. Rev. Lett. 74, 1542–1545 (1995)

    ADS  CAS  Article  Google Scholar 

  17. Greiner, M., Bloch, I., Mandel, O., Hansch, T. W. & Esslinger, T. Exploring phase coherence in a 2D lattice of Bose-Einstein condensates. Phys. Rev. Lett. 87, 160405 (2001)

    ADS  CAS  Article  Google Scholar 

  18. Lidar, D. A., Chuang, I. L. & Whaley, K. B. Decoherence-free subspaces for quantum computation. Phys. Rev. Lett. 81, 2594–2597 (1998)

    ADS  CAS  Article  Google Scholar 

  19. Petta, J. R. et al. Coherent manipulation of coupled electron spins in semiconductor quantum dots. Science 309, 2180–2184 (2005)

    ADS  CAS  Article  Google Scholar 

  20. Sebby-Strabley, J. et al. Preparing and probing atomic number states with an atom interferometer. Phys. Rev. Lett. 98, 200405 (2007)

    ADS  CAS  Article  Google Scholar 

  21. Widera, A. et al. Coherent collisional spin dynamics in optical lattices. Phys. Rev. Lett. 95, 190405 (2005)

    ADS  Article  Google Scholar 

  22. Calarco, T., Dorner, U., Julienne, P. S., Williams, C. J. & Zoller, P. Quantum computations with atoms in optical lattices: Marker qubits and molecular interactions. Phys. Rev. A. 70, 012306 (2004)

    ADS  Article  Google Scholar 

  23. Matthews, M. R. et al. Dynamical response of a Bose-Einstein condensate to a discontinuous change in internal state. Phys. Rev. Lett. 81, 243–247 (1998)

    ADS  CAS  Article  Google Scholar 

  24. Zhang, C. W., Rolston, S. L. & Das Sarma, S. Manipulation of single neutral atoms in optical lattices. Phys. Rev. A. 74, 042316 (2006)

    ADS  Article  Google Scholar 

  25. Altman, E., Hofstetter, W., Demler, E. & Lukin, M. D. Phase diagram of two-component bosons on an optical lattice. N. J. Phys. 5, 113–(1–19) (2003)

    Article  Google Scholar 

  26. Scarola, V. W. & Das Sarma, S. Quantum phases of the extended Bose-Hubbard hamiltonian: Possibility of a supersolid state of cold atoms in optical lattices. Phys. Rev. Lett. 95, 033003 (2005)

    ADS  CAS  Article  Google Scholar 

  27. Isacsson, A. & Girvin, S. M. Multiflavor bosonic Hubbard models in the first excited Bloch band of an optical lattice. Phys. Rev. A. 72, 053604 (2005)

    ADS  Article  Google Scholar 

  28. Jané, E., Vidal, G., Dür, W., Zoller, P. & Cirac, J. I. Simulation of quantum dynamics with quantum optical systems. Quantum Inf. Comput. 3, 15–37 (2003)

    MathSciNet  MATH  Google Scholar 

  29. Sørensen, A. & Mølmer, K. Spin-spin interaction and spin squeezing in an optical lattice. Phys. Rev. Lett. 83, 2274–2277 (1999)

    ADS  Article  Google Scholar 

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Acknowledgements

We thank I. Spielman and S. Rolston for contributions to the project, and I. Deutsch for discussions. P.J.L., B.L.B. and J.S.-S. acknowledge support from the National Research Council Postdoctoral Research Associateship Program. This work was supported by DTO, ONR and NASA.

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Correspondence to J. V. Porto.

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Anderlini, M., Lee, P., Brown, B. et al. Controlled exchange interaction between pairs of neutral atoms in an optical lattice. Nature 448, 452–456 (2007). https://doi.org/10.1038/nature06011

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