Studying an unbalanced two-ion crystal in a Penning trapTowards the quantum regime in a high magnetic field

Resumo

This Thesis has been devoted to study a new technique based on two simultaneously trapped ions with prospects for high-accuracy Penning-trap mass spectrometry. One of the two ions (called sensor) can be laser cooled, either to the Doppler limit or to the ground state. The other ion (called target), although not directly interacting with any laser, is sympathetically cooled to the same temperature by the Coulomb interaction. In this scenario, a crystal is formed. Information about the oscillations of the crystal is read out through photons scattered by the sensor ion. The unbalanced two-ion crystal has been theoretically studied for the rst time in a Penning trap in the course of this Thesis. A detailed study and analysis of the motional frequencies of the crystal has been carried out. The implications of the anharmonicities introduced by the Coulomb interaction in the frequency measurement process, quantifying shifts in the classical and in the quantum regime, have been studied. Part of these results have been published in Physical Review A and the software package built for this is available to the ion-trapping community. The experimental component of this thesis has two parts: i) the implementation of a new control and data acquisition system based on ARTIQ (Advanced Real-Time Infrastructure for Quantum physics), and ii) the study, modi cations and improvements around the open-ring Penning trap, where the crystal is formed. The work with ARTIQ has integrated the devices needed for ion trapping, dipolar/quadrupolar driving and image collection. The work on the open-ring Penning trap started by implementing a custom Laplace-solver program to stablish a tuning procedure that minimizes anharmonic terms. After that, technical issues related to ion production and lasers were overcome. The results, including the rst evidence of laser cooling of 40Ca+ under 7 Tesla, have been published in New Journal of Physics. The Thesis ends by showing our rst two-ion crystal, an unique experimental platform for the envisaged studies.