title: Simplest molecules as candidates for precise optical clocks.
abstract: The precise measurement of transition frequencies in cold, trapped molecules has applications in fundamental physics, and extremely high accuracies are desirable. We determine suitable candidates by considering the simplest molecules with a single electron, for which the external-field shift corrections can be calculated theoretically with high precision. Our calculations show that H(2)(+) exhibits particular transitions whose fractional systematic uncertainties may be reduced to 5×10(-17) at room temperature. We also generalize the method of composite frequencies, introducing tailored linear combinations of individual transition frequencies that are free of the major systematic shifts, independent of the strength of the external perturbing fields. By applying this technique, the uncertainty of the composite frequency is reduced compared to what is achievable with a single transition, e.g., to the 10(-18) range for HD(+). Thus, these molecules are of metrological relevance for future studies.
authors: Institut für Experimentalphysik, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany.
authors: S
authors: S
authors: Schiller
authors: Institute for Nuclear Research and Nuclear Energy, Tsarigradsko Chaussée 72, Sofia 1784, Bulgaria.
authors: D
authors: D
authors: Bakalov
authors: Joint Institute for Nuclear Research, 141980 Dubna, Russia.
authors: V I
authors: VI
authors: Korobov