The measurement of the oscillatory motion of trapped ions is used in physics to perform stringent tests of quantum mechanics and precision measurements of the rest energies of fundamental particles. We have developed a new experimental method that allows measuring the oscillation of an isolated ion or a two-ion chain, which is based on the manipulation and detection of the fluorescence light emitted by the ions (see image (a)). In our apparatus, a distant mirror reflects part of the fluorescence radiation emitted by the ions back towards the ion. This setup allows us to self-interfere the fluorescence photons emitted by the ions. The interference of the primary and reflected fluorescence is constructive or destructive at our single-mode fiber detectors (SMFD) depending on the ion-mirror distance q. This feature enabled us to measure the oscillations of a single trapped ion with quantum sensitivity by controlling the position of the macroscopic mirror [1]. Compared to other methods, the new technique allows detecting all the oscillations' frequencies of the trapped ion simultaneously by only using the Doppler cooling radiation. The new method is suitable for precision studies of complex ion chains, in which one ion of interest may not be interacting with the light field, but is cooled and observed via the fluorescence emitted by the second ion (see image (b) and (c)) [2].
Links
[1] "Measuring Ion Oscillations at the Quantum Level with Fluorescence Light" G. Cerchiari, G. Araneda, L. Podhora, L. Slodička, Y. Colombe, and R. Blatt, Phys. Rev. Lett. 127, 063603 (2021) G. Cerchiari, G. Araneda, L. Podhora, L. Slodička, Y. Colombe, and R. Blatt, Phys. Rev. Lett. 127, 063603 (2021) G. Cerchiari, G. Araneda, L. Podhora, L. Slodička, Y. Colombe, and R. Blatt, Phys. Rev. Lett. 127, 063603 (2021)