Precision spectroscopy by photon-recoil signal amplification

• DOI: 10.1038/ncomms4096
• Publication Date: 2014-01-30T09:56:23Z
• Authors: Yong Wan; Florian Gebert; Jannes B Wübbena; Nils Scharnhorst; Sana Amairi; Ian D Leroux; Börge Hemmerling; Niels Lörch; Klemens Hammerer; Piet O Schmidt
• Keywords: Recoil; Laser linewidth

Precision spectroscopy of atomic and molecular ions offers a window to new physics, but is typically limited to species with a cycling transition for laser cooling and detection. Quantum logic spectroscopy has overcome this limitation for species with long-lived excited states. Here we extend quantum logic spectroscopy to fast, dipole-allowed transitions and apply it to perform an absolute frequency measurement. We detect the absorption of photons by the spectroscopically investigated ion through the photon recoil imparted on a co-trapped ion of a different species, on which we can perform efficient quantum logic detection techniques. This amplifies the recoil signal from a few absorbed photons to thousands of fluorescence photons. We resolve the line centre of a dipole-allowed transition in Ca-40(+) to 1/300 of its observed linewidth, rendering this measurement one of the most accurate of a broad transition. The simplicity and versatility of this approach enables spectroscopy of many previously inaccessible species.