Localized visible Ba+ mono-ion oscillator

Abstract

An individual barium ion, continuously observed by laser fluorescence, has been isolated in a Paul rf quadrupole trap at room temperature. By optical sideband cooling its microscopically measured image has been reduced in thickness to 2 m in the object plane, the diffraction limit. Estimated ion temperatures reached are Ti10 to <36 mK. With cooling, the ion could be held indefinitely, without cooling30 s. In the future the technique seems capable of attaining kinetic temperatures 10-8 K, much lower than realized so far by other means, with corresponding far-reaching implications. © 1980 The American Physical Society.