Control over physical systems at the quantum level is important in fields as diverse as metrology, information processing, simulation and chemistry. For trapped atomic ions, the quantized motional and internal degrees of freedom can be coherently manipulated with laser light1,2. Similar control is difficult to achieve with radio-frequency or microwave radiation: the essential coupling between internal degrees of freedom and motion requires significant field changes over the extent of the atoms’ motion2,3, but such changes are negligible at these frequencies for freely propagating fields. An exception is in the near field of microwave currents in structures smaller than the free-space wavelength4,5, where stronger gradients can be generated. Here we first manipulate coherently (on timescales of 20 nanoseconds) the internal quantum states of ions held in a microfabricated trap. The controlling magnetic fields are generated by microwave currents in electrodes that are integrated into the trap structure. We also generate entanglement between the internal degrees of freedom of two atoms with a gate operation4,6,7,8 suitable for general quantum computation9; the entangled state has a fidelity of 0.76(3), where the uncertainty denotes standard error of the mean. Our approach, which involves integrating the quantum control mechanism into the trapping device in a scalable manner, could be applied to quantum information processing4, simulation5,10 and spectroscopy3,11.
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Blatt, R. & Wineland, D. J. Entangled states of trapped atomic ions. Nature 453, 1008–1015 (2008)
Leibfried, D., Blatt, R., Monroe, C. & Wineland, D. J. Quantum dynamics of single trapped ions. Rev. Mod. Phys. 75, 281–324 (2003)
Wineland, D. J. et al. Experimental issues in coherent quantum-state manipulation of trapped atomic ions. J. Res. Natl Inst. Stand. Technol. 103, 259–328 (1998)
Ospelkaus, C. et al. Trapped-ion quantum logic gates based on oscillating magnetic fields. Phys. Rev. Lett. 101, 090502 (2008)
Chiaverini, J. & Lybarger, W. E. Laserless trapped-ion quantum simulations without spontaneous scattering using microtrap arrays. Phys. Rev. A 77, 022324 (2008)
Sørensen, A. & Mølmer, K. Quantum computation with ions in thermal motion. Phys. Rev. Lett. 82, 1971–1974 (1999)
Solano, E., de Matos Filho, R. L. & Zagury, N. Deterministic Bell states and measurement of the motional state of two trapped ions. Phys. Rev. A 59, R2539–R2543 (1999)
Milburn, G. J., Schneider, S. & James, D. F. V. Ion trap quantum computing with warm ions. Fortschr. Phys. 48, 801–810 (2000)
Barenco, A. et al. Elementary gates for quantum computation. Phys. Rev. A 52, 3457–3467 (1995)
Schmied, R., Wesenberg, J. H. & Leibfried, D. Optimal surface-electrode trap lattices for quantum simulation with trapped ions. Phys. Rev. Lett. 102, 233002 (2009)
Schmidt, P. O. et al. Spectroscopy using quantum logic. Science 309, 749–752 (2005)
Knoop, M. Hilico, L. & Eschner, J. (eds) Modern Applications of Trapped Ions (J. Phys. B Vol. 42, Institute of Physics, 2009)
Porras, D. & Cirac, J. I. Effective quantum spin systems with trapped ions. Phys. Rev. Lett. 92, 207901 (2004)
Friedenauer, A., Schmitz, H., Glueckert, J. T., Porras, D. & Schaetz, T. Simulating a quantum magnet with trapped ions. Nature Phys. 4, 757–761 (2008)
Kim, K. et al. Quantum simulation of frustrated Ising spins with trapped ions. Nature 465, 590–593 (2010)
Mintert, F. & Wunderlich, C. Ion-trap quantum logic using long-wavelength radiation. Phys. Rev. Lett. 87, 257904 (2001)
Ciaramicoli, G., Marzoli, I. & Tombesi, P. Scalable quantum processor with trapped electrons. Phys. Rev. Lett. 91, 017901 (2003)
Johanning, M. et al. Individual addressing of trapped ions and coupling of motional and spin states using RF radiation. Phys. Rev. Lett. 102, 073004 (2009)
Förster, L. et al. Microwave control of atomic motion in optical lattices. Phys. Rev. Lett. 103, 233001 (2009)
Wang, S. X., Labaziewicz, J., Ge, Y., Shewmon, R. & Chuang, I. L. Individual addressing of ions using magnetic field gradients in a surface-electrode ion trap. Appl. Phys. Lett. 94, 094103 (2009)
Fortágh, J. & Zimmermann, C. Magnetic microtraps for ultracold atoms. Rev. Mod. Phys. 79, 235–289 (2007)
Amini, J. M. et al. Toward scalable ion traps for quantum information processing. New J. Phys. 12, 033031 (2010)
Seidelin, S. et al. Microfabricated surface-electrode ion trap for scalable quantum information processing. Phys. Rev. Lett. 96, 253003 (2006)
Langer, C. et al. Long-lived qubit memory using atomic ions. Phys. Rev. Lett. 95, 060502 (2005)
Jost, J. D. et al. Entangled mechanical oscillators. Nature 459, 683–685 (2009)
Campbell, W. C. et al. Ultrafast gates for single atomic qubits. Phys. Rev. Lett. 105, 090502 (2010)
King, B. E. et al. Cooling the collective motion of trapped ions to initialize a quantum register. Phys. Rev. Lett. 81, 1525–1528 (1998)
Hayes, D. et al. Coherent error suppression in spin-dependent force quantum gates. Preprint at 〈http://arxiv.org/abs/1104.1347〉 (2011)
Sackett, C. A. et al. Experimental entanglement of four particles. Nature 404, 256–259 (2000)
Levitt, M. H. Composite pulses. Prog. Nucl. Magn. Reson. Spectrosc. 18, 61–122 (1986)
Heinzen, D. J. & Wineland, D. J. Quantum-limited cooling and detection of radio-frequency oscillations by laser-cooled ions. Phys. Rev. A 42, 2977–2994 (1990)
Brown, K. R. et al. Coupled quantized mechanical oscillators. Nature 471, 196–199 (2011)
Harlander, M., Lechner, R., Brownnutt, M., Blatt, R. & Hänsel, W. Trapped-ion antennae for the transmission of quantum information. Nature 471, 200–203 (2011)
We thank M. J. Biercuk, J. J. Bollinger and A. P. VanDevender for experimental assistance, J. C. Bergquist, C. W. Chou and T. Rosenband for the loan of a fibre laser, R. Jordens and E. Knill for comments on the manuscript, and D. Hanneke and J. P. Home for discussions. We thank P. Treutlein for discussions on microfabrication techniques. This work was supported by IARPA, the ONR, DARPA, the NSA, Sandia National Laboratories and the NIST Quantum Information Program. This paper, a submission of NIST, is not subject to US copyright.
The authors declare no competing financial interests.
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Ospelkaus, C., Warring, U., Colombe, Y. et al. Microwave quantum logic gates for trapped ions. Nature 476, 181–184 (2011). https://doi.org/10.1038/nature10290
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