Stuttgart 2012 – scientific programme
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A: Fachverband Atomphysik
A 21: Poster: Precision spectroscopy of atoms and ions
A 21.4: Poster
Tuesday, March 13, 2012, 16:30–19:00, Poster.V
Prospects for quantum logic spectroscopy of molecular ions — •Yong Wan, Florian Gebert, and Piet O. Schmidt — QUEST Institute for Experimental Quantum Metrology, PTB, Braunschweig
The rapid development in laser cooling and coherent state manipulation over the past decades demonstrated exquisite control of the internal and external degrees of freedom of various species of atomic ions. The same technique can not be easily applied to molecular ions because of their rich internal level structure. On the other hand, ultra cold molecular ions lend themselves for a number of novel applications, ranging from cold chemistry to tests of fundamental theories.
To overcome the obstacle of laser cooling and to achieve a deterministic internal state preparation, we propose to employ the quantum logic technique [1] in which a laser-cooled atomic ion is simultaneously trapped with a single molecular ion. The cooling of the external degrees of freedom of the molecular ion is achieved via sympathetic cooling by the sideband-cooled atomic ion, while the preparation of its internal state will be achieved via a quantum-non-demolition measurement.
The investigated molecules MgH+/CaH+ are relevant for the search of a possible temporal variation of the electron-to-proton mass µ = me/mp [2]. The transition frequency of rovibrational overtone transitions in the molecule depend on µ and can be compared to another optical reference, such as the Al+ clock to obtain an improved upper limit for the time variation of µ.
[1] Schmidt et al., Science 309, 749 (2005)
[2] Kajita et al., J. Phys. B 42, 154022 (2009)