Injection locking of a trapped-ion phonon laser.

We report on injection locking of optically excited mechanical oscillations of a single, trapped ion. The injection locking dynamics are studied by analyzing the oscillator spectrum with a spatially selective Fourier transform technique and the oscillator phase with stroboscopic imaging. In both cases we find excellent agreement with theory inside and outside the locking range. We attain injection locking with forces as low as 5(1)×10{-24} N so this system appears promising for the detection of ultraweak oscillating forces.

Frequency metrology on single trapped ions in the weak binding limit: the 3s(1/2)-3p(3/2) transition in 24Mg+.

We demonstrate a method for precision spectroscopy on trapped ions in the limit of unresolved motional sidebands. By sympathetic cooling of a chain of crystallized ions, we suppress adverse temperature variations induced by the spectroscopy laser that usually lead to a distorted line profile and obtain a Voigt profile with negligible distortions. We applied the method to measure the absolute frequency of the astrophysically relevant D2 transition in single 24Mg+ ions and find 1 072 082 934.33(16) MHz, a nearly 400-fold improvement over previous results. Further, we find the excited state lifetime to be 3.84(10) ns.