Stuttgart 2012 – scientific programme

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MO: Fachverband Molekülphysik

MO 5: Experimental Techniques

MO 5.6: Talk

Monday, March 12, 2012, 17:45–18:00, V38.02

Identification and Non-destructive State Detection of Molecular Ions — Kevin Sheridan, Amy Gardner, Nic Seymour-Smith, and •Matthias Keller — University of Sussex, UK

Cold molecules have a multitude of applications ranging from high resolution spectroscopy and tests of fundamental theories to cold chemistry and, potentially, quantum information processing. Prerequisite for these applications is the cooling of the molecules' motion and its non-invasive identification. Furthermore, the internal state of the molecules needs to be prepared and non-destructively detected. The cooling of the motion and trapping of molecular ions can be accomplished by trapping them in an rf-trap alongside laser cooled atomic ions. We have developed a novel technique to measure the average charge to mass ratio of trapped ions with high precision by broadband excitation of the ions' COM-mode motion and measuring their laser induced fluorescence. The FFT of the fluorescence's autocorrelation provides the COM-mode spectrum with a good SNR for measurement times as low as 100ms and kinetic energy injections of less than a few mK. The method is limited only by the required interrogation time and the motional coupling of the constituents of the mixed ion crystal. Employing state selective laser induced dipole forces we aim to detect the internal state of molecular ions by mapping the state information onto the ions' motion. The scheme promises mitigation of the effect of laser polarisation and the distribution of population across Zeeman sublevels and it may be applicable for a larger number of simultaneously trapped molecules.