Marcelo Alejandro Luda

In this work, we present the design, implementation, and construction of a linear Paul trap in a blade configuration. The trap was optimized to minimize micromotion and enable the formation of linear ion chains comprising tens of ions. We use ytterbium atoms, and in particular, we describe the trapping and cooling of the isotopes $^{174} \mathrm{Yb}^+$ and $^{171} \mathrm{Yb}^+$, starting from an isotope-selective ionization process based on laser frequency stabilization and optimization of fluorescence for each isotope. The electronic control system-including magnetic field generation, laser delivery, and microwave driving-was fully implemented and is described in detail. The system supports pulsed operation, and we performed Rabi oscillations of the hyperfine states in the $^2 \mathrm{S}_{1/2}$ level, demonstrating coherent spectroscopy. These capabilities are fundamental tools for the experiments we aim to pursue, including the use of structured light beams, quantum simulation protocols, and the generation of non-classical motional states.

We present an experiment investigating the rotational Doppler effect using a single trapped ion excited by two copropagating vortex laser beams. The setup isolates the azimuthal gradients of the fields, eliminating longitudinal and curvature effects. We provide a detailed characterization of the phenomenon by deterministically positioning a single ion across the beams, achieving a signal which depends on the angular velocity of the ion and the difference of optical orbital angular momentum between the two beams. The interpretation of the measurements is supported by numerical simulations and by a simplified analytical model. Our results reveal key properties of the rotational Doppler effect, showing that it increases approaching the center of the beam and that it is independent of the waist of the beam. This offers insights into the feasibility of super-kicks or super-Doppler shifts for sensing and manipulating atomic motion transverse to the beams' propagation direction.

We study the influence of micromotion on the spectrum of trapped ions with a lambda-type level scheme, leading to dark resonances due to coherent population trapping. We work with calcium ions trapped in a ring-shaped Paul trap, in which one can compensate excess micromotion for only one ion of the crystal. We observe that micromotion affects the shapes of the dark resonances and causes the appearance of "echoes" separated by intervals given by the drive frequency. We present a theoretical model that provides good fits to the measurements and can be used to estimate the amplitude of the micromotion modulation of the atomic motion. We estimate an effective temperature of the ions from the spectra and observe clear micromotion heating as well as impaired cooling for sufficiently large excess micromotion.