Cold Molecules and Quantum Computation

Coupling Polar Molecules to Superconducting Microwave Resonators

Molecule Cavity

Isolated molecular systems are unique for their exceptional coherence properties, making them excellent candidates for quantum information applications. We would like to implement a coupled molecule-superconducting on-chip cavity system at microwave frequencies. Polar molecules like CaF, CaBr possess rotational energy levels in the microwave frequencies regime, which make them suitable for strong coupling to a superconducting stripline resonator.

Through the Stark interaction of the molecular dipoles with applied static electric fields, polar molecules of certain rotational states can be trapped in localized field minima produced by electrostatic electrodes in planar geometries. Molecules trapped in proximity to the surface of a superconducting stripline resonator can be strongly coupled and residual motional energy of the molecules can be removed through dissipation into the cavity (sideband cooling). A microwave dispersive measurement similar to that done in our qubit-resonator systems can then be performed on the molecule rotational state.

Our immediate tasks involve designing effective electrostatic trap geometries as well as developing an efficient molecule loading scheme. Some current ideas include an electrostatic Z-trap geometry analogous to the Magnetic Z Trap developed in the context of "atom chips" [Folman, 2002] as well as an optically assisted selective state molecule loading system.

Publications:

  • A coherent all-electrical interface between polar molecules and mesoscopic superconducting resonators
    A. André, D. DeMille, J. M. Doyle, M. D. Lukin, S. E. Maxwell, P. Rabl, R. J. Schoelkopf, and P. Zoller. Nature Physics (London) 2 636 (2006), doi:10.1038/nphys386 (quant-ph/0605201)
  • Hybrid Quantum Processors: Molecular Ensembles as Quantum Memory for Solid State Circuits
    P. Rabl, D. DeMille, J. M. Doyle, M. D. Lukin, R. J. Schoelkopf, and P. Zoller. PRL 97, 033003 (2006), doi:10.1103/PhysRevLett.97.033003 (quant-ph/0604140)