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Entangling two transportable neutral atoms via local spin exchange

Nature volume 527, pages 208–211 (2015)Cite this article

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Abstract

To advance quantum information science, physical systems are sought that meet the stringent requirements for creating and preserving quantum entanglement. In atomic physics, robust two-qubit entanglement is typically achieved by strong, long-range interactions in the form of either Coulomb interactions between ions or dipolar interactions between Rydberg atoms1,2,3,4. Although such interactions allow fast quantum gates, the interacting atoms must overcome the associated coupling to the environment and cross-talk among qubits5,6,7,8. Local interactions, such as those requiring substantial wavefunction overlap, can alleviate these detrimental effects; however, such interactions present a new challenge: to distribute entanglement, qubits must be transported, merged for interaction, and then isolated for storage and subsequent operations. Here we show how, using a mobile optical tweezer, it is possible to prepare and locally entangle two ultracold neutral atoms, and then separate them while preserving their entanglement9,10,11. Ground-state neutral atom experiments have measured dynamics consistent with spin entanglement10,12,13, and have detected entanglement with macroscopic observables14,15; we are now able to demonstrate position-resolved two-particle coherence via application of a local gradient and parity measurements1. This new entanglement-verification protocol could be applied to arbitrary spin-entangled states of spatially separated atoms16,17. The local entangling operation is achieved via spin-exchange interactions9,10,11, and quantum tunnelling is used to combine and separate atoms. These techniques provide a framework for dynamically entangling remote qubits via local operations within a large-scale quantum register.

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Figure 1: Experimental overview.
Figure 2: Direct observation of spin-exchange dynamics between two atoms.
Figure 3: Detection of non-local entanglement.

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References

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

    Article  ADS  CAS  Google Scholar 

  2. Leibfried, D. et al. Experimental demonstration of a robust, high-fidelity geometric two ion-qubit phase gate. Nature 422, 412–415 (2003)

    Article  ADS  CAS  Google Scholar 

  3. Wilk, T. et al. Entanglement of two individual neutral atoms using Rydberg blockade. Phys. Rev. Lett. 104, 010502 (2010)

    Article  ADS  CAS  Google Scholar 

  4. Isenhower, L. et al. Demonstration of a neutral atom controlled-NOT quantum gate. Phys. Rev. Lett. 104, 010503 (2010)

    Article  ADS  CAS  Google Scholar 

  5. Monroe, C. et al. Resolved-sideband Raman cooling of a bound atom to the 3D zero-point energy. Phys. Rev. Lett. 75, 4011–4014 (1995)

    Article  ADS  MathSciNet  CAS  Google Scholar 

  6. Blakestad, R. et al. High-fidelity transport of trapped-ion qubits through an X-junction trap array. Phys. Rev. Lett. 102, 153002 (2009)

    Article  ADS  CAS  Google Scholar 

  7. Home, J. P. et al. Complete methods set for scalable ion trap quantum information processing. Science 325, 1227–1230 (2009)

    Article  ADS  MathSciNet  CAS  Google Scholar 

  8. Béguin, L., Vernier, A., Chicireanu, R., Lahaye, T. & Browaeys, A. Direct measurement of the van der Waals interaction between two Rydberg atoms. Phys. Rev. Lett. 110, 263201 (2013)

    Article  ADS  Google Scholar 

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

    Article  ADS  Google Scholar 

  10. Anderlini, M. et al. Controlled exchange interaction between pairs of neutral atoms in an optical lattice. Nature 448, 452–456 (2007)

    Article  ADS  CAS  Google Scholar 

  11. Weitenberg, C., Kuhr, S., Mølmer, K. & Sherson, J. Quantum computation architecture using optical tweezers. Phys. Rev. A 84, 032322 (2011)

    Article  ADS  Google Scholar 

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

    Article  ADS  CAS  Google Scholar 

  13. Fukuhara, T. et al. Quantum dynamics of a mobile spin impurity. Nature Phys. 9, 235–241 (2013)

    Article  ADS  CAS  Google Scholar 

  14. Lücke, B. et al. Twin matter waves for interferometry beyond the classical limit. Science 334, 773–776 (2011)

    Article  ADS  Google Scholar 

  15. Strobel, H. et al. Fisher information and entanglement of non-Gaussian spin states. Science 345, 424–427 (2014)

    Article  ADS  CAS  Google Scholar 

  16. Mazza, L., Rossini, D., Fazio, R. & Endres, M. Detecting two-site spin-entanglement in many-body systems with local particle-number fluctuations. New J. Phys. 17, 013015 (2015)

    Article  ADS  CAS  Google Scholar 

  17. Fukuhara, T. et al. Spatially resolved detection of a spin-entanglement wave in a Bose-Hubbard chain. Phys. Rev. Lett. 115, 035302 (2015)

    Article  ADS  Google Scholar 

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

    Article  ADS  CAS  Google Scholar 

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

    Article  ADS  CAS  Google Scholar 

  20. Trotzky, S. et al. Time-resolved observation and control of superexchange interactions with ultracold atoms in optical lattices. Science 319, 295–299 (2008)

    Article  ADS  CAS  Google Scholar 

  21. Kotler, S., Akerman, N., Navon, N., Glickman, Y. & Ozeri, R. Measurement of the magnetic interaction between two bound electrons of two separate ions. Nature 510, 376–380 (2014)

    Article  ADS  CAS  Google Scholar 

  22. Daley, A. J., Pichler, H., Schachenmayer, J. & Zoller, P. Measuring entanglement growth in quench dynamics of bosons in an optical lattice. Phys. Rev. Lett. 109, 020505 (2012)

    Article  ADS  CAS  Google Scholar 

  23. Greif, D., Uehlinger, T., Jotzu, G., Tarruell, L. & Esslinger, T. Short-range quantum magnetism of ultracold fermions in an optical lattice. Science 340, 1307–1310 (2013)

    Article  ADS  CAS  Google Scholar 

  24. Murmann, S. et al. Two fermions in a double well: exploring a fundamental building block of the Hubbard model. Phys. Rev. Lett. 114, 080402 (2015)

    Article  ADS  Google Scholar 

  25. Hart, R. A. et al. Observation of antiferromagnetic correlations in the Hubbard model with ultracold atoms. Nature 519, 211–214 (2015)

    Article  ADS  CAS  Google Scholar 

  26. Schlosser, N., Reymond, G., Protsenko, I. & Grangier, P. Sub-poissonian loading of single atoms in a microscopic dipole trap. Nature 411, 1024–1027 (2001)

    Article  ADS  CAS  Google Scholar 

  27. Kaufman, A. M., Lester, B. J. & Regal, C. A. Cooling a single atom in an optical tweezer to its quantum ground state. Phys. Rev. X 2, 041014 (2012)

    Google Scholar 

  28. Kaufman, A. M. et al. Two-particle quantum interference in tunnel-coupled optical tweezers. Science 345, 306–309 (2014)

    Article  ADS  MathSciNet  CAS  Google Scholar 

  29. Kielpinski, D. et al. A decoherence-free quantum memory using trapped ions. Science 291, 1013–1015 (2001)

    Article  ADS  CAS  Google Scholar 

  30. Wall, M. L., Hazzard, K. R. A. & Rey, A. M. Effective many-body parameters for atoms in nonseparable Gaussian optical potentials. Phys. Rev. A 92, 013610 (2015)

    Article  ADS  Google Scholar 

  31. Weitenberg, C. et al. Single-spin addressing in an atomic Mott insulator. Nature 471, 319–324 (2011)

    Article  ADS  CAS  Google Scholar 

  32. Stewart, G. R. Heavy-fermion systems. Rev. Mod. Phys. 56, 755–787 (1984)

    Article  ADS  CAS  Google Scholar 

  33. Peres, A. Separability criterion for density matrices. Phys. Rev. Lett. 77, 1413–1415 (1996)

    Article  ADS  MathSciNet  CAS  Google Scholar 

  34. Horodecki, M., Horodecki, P. & Horodecki, R. Separability of mixed states: necessary and sufficient conditions. Preprint at http://arXiv.org/abs/quant-ph/9605038 (1996)

Download references

Acknowledgements

This work was supported by the David and Lucile Packard Foundation and the National Science Foundation under grant number 1125844. C.A.R. acknowledges support from the Clare Boothe Luce Foundation. M.L.W. and A.M.R. acknowledge funding from NSF-PIF, ARO, ARO-DARPA-OLE and AFOSR. M.L.W. and M.F.-F. acknowledge support from the NRC postdoctoral fellowship program.

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Authors and Affiliations

  1. JILA, National Institute of Standards and Technology and University of Colorado, Boulder, 80309, Colorado, USA

    A. M. Kaufman, B. J. Lester, M. L. Wall, A. M. Rey & C. A. Regal

  2. Department of Physics, University of Colorado, Boulder, 80309, Colorado, USA

    A. M. Kaufman, B. J. Lester, A. M. Rey & C. A. Regal

  3. Joint Quantum Institute and the National Institute of Standards and Technology, Gaithersburg, 20899, Maryland, USA

    M. Foss-Feig

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  1. A. M. Kaufman
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  3. M. Foss-Feig
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  4. M. L. Wall
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Contributions

A.M.K. and B.J.L. took the data and performed the data analysis, with guidance from C.A.R. M.F.F., M.L.W. and A.M.R. provided theoretical support. All authors contributed to the writing of the manuscript.

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Correspondence to C. A. Regal.

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The authors declare no competing financial interests.

Extended data figures and tables

Extended Data Figure 1 Adiabatic energy eigenstates E as a function of the double-well bias Δ in units of the ground-excited tunnelling Jeg.

At large positive bias, the triplet and singlet eigenstates corresponding to two particles in the same well are split by Jex. The dashed and solid lines denote the energies of the states that asymptotically connect to the states labelled in the figure through the AP process. See Methods for details.

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Kaufman, A., Lester, B., Foss-Feig, M. et al. Entangling two transportable neutral atoms via local spin exchange. Nature 527, 208–211 (2015). https://doi.org/10.1038/nature16073

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