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A coherent all-electrical interface between polar molecules and mesoscopic superconducting resonators


Building a scalable quantum processor requires coherent control and preservation of quantum coherence in a large-scale quantum system. Mesoscopic solid-state systems such as Josephson junctions and quantum dots feature robust control techniques using local electrical signals and self-evident scaling; however, in general the quantum states decohere rapidly. In contrast, quantum optical systems based on trapped ions and neutral atoms exhibit much better coherence properties, but their miniaturization and integration with electrical circuits remains a challenge. Here we describe methods for the integration of a single-particle system—an isolated polar molecule—with mesoscopic solid-state devices in a way that produces robust, coherent, quantum-level control. Our setup provides a scalable cavity-QED-type quantum computer architecture, where entanglement of distant qubits stored in long-lived rotational molecular states is achieved via exchange of microwave photons.

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Figure 1: The structure of selected rotational states of CaBr in an electric field.
Figure 2: Electrostatic Z-trap.
Figure 3: Resonator-enhanced sideband cooling and quantum state readout.
Figure 4: Capacitive coupling of molecules mediated by a stripline.


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We thank T. Calarco, L. Childress, A. Sorensen and J. Taylor for helpful discussions. Work at Harvard is supported by NSF, Harvard-MIT CUA and Packard and Sloan Foundations. Work at Yale is supported by NSF Grant DMR0325580, the W.M. Keck Foundation and the Army Research Office. Work at Innsbruck is supported by the Austrian Science Foundation, European Networks and the Institute for Quantum Information. J.M.D. would like to thank the Humboldt Foundation and G. Meijer for their support.

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Correspondence to M. D. Lukin.

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André, A., DeMille, D., Doyle, J. et al. A coherent all-electrical interface between polar molecules and mesoscopic superconducting resonators. Nature Phys 2, 636–642 (2006).

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