Geometric phase gates for trapped molecular ions

Stefan Willitsch, Xin Tong, Matthias Germann 

Department of Chemistry, University of Basel

Based on a recently established method to initialize sympathetically-cooled molecular ions in ion traps in a well-defined internal (rotational-vibrational) quantum state [1] we are developing methods to utilize single trapped molecular ions as new systems for quantum simulation, computation and precision measurements. For this purpose, we are implementing specially tailored geometric-phase gates to perform quantum logic  between a single trapped atomic ion which acts as a probe, and a single target molecular ion the internal state of which is to be determined non-destructively [2]. Our approach relies on a hybrid coherent manipulation of the two-ion system, using optical forces depending on the precise internal states of the molecular ion. This approach is insensitive to the temperature of the ions and does not require resolved-sideband cooling as other hybrid manipulation schemes [3,4]. An immediate first application of these gates represents the precise and non-destructive determination of molecular parameters from single molecules. Second, the approach represents a new approach to molecular spectroscopy which relies on the manipulation of quantum phases. Finally, this quantum gate represents the corner stone of a hybrid quantum computation scheme which combines molecular and atomic ions, covering the initialization, entangling and measurement steps.

References:
[1] X. Tong. A. H. Winney, and S. Willitsch, Phys. Rev. Lett. 150, 143001 (2010)
[2] J. Mur-Petit, J. J. García-Ripoll and S. Willitsch, Phys. Rev. A. 85, 022308 (2012).
[3] P. O. Schmidt, T. Rosenband, and D. J. Wineland, Science, 309, 749 (2005)
[4] P.O. Schmidt et al., AIP Conf. Proc. CP862, 305 (2006)