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Abstract

Simultaneous control over both excitational and motional degrees of freedom of quantum objects facilitates measurement accuracies at a level that enables the measurement of subtle relativistic effects, tests of the Standard Model and even the search for expected effects of physics beyond it. Theoretical calculations predict enhanced sensitivities of forbidden optical transitions in highly charged ions (HCIs) to possible variations of fundamental constants, such as the fine structure constant. Within this thesis, a versatile preparation technique of cold and strongly localized HCIs has been developed and demonstrated, adding a multitude of laser accessible systems to the quantum toolbox, that have enhanced sensitivity to fundamental physics. HCIs are extracted from an electron beam ion trap (EBIT), where they are produced in the MK temperature range. Subsequently they are cooled down to the mK regime, needed for high precision laser spectroscopy, in a cryogenic linear Paul trap. Deceleration, precooling and multi-pass stopping approaches enable HCI implantation within a prestored, continuously laser-cooled Be+-Coulomb crystal. Here the HCIs are co-crystallized in mixed-species ensembles (specifically Ar¹³⁺ highly charged and Be⁺ coolant ions) - ranging from large 3-dimensional crystals over ion strings down to a single Ar¹³⁺ ion cooled by a single Be⁺ ion. The precooling, retrapping and sympathetic stopping process, as well as various Coulomb crystal configurations are characterized and compared to simulations and theoretical models. The developed experimental concept and its modular implementation enable, for the first time, the localization of HCIs in a microscopic region of a Paul trap, today's standard method for singly-charged ion frequency metrology. This is a necessary prerequisite for the development of novel ultra-precise optical clocks based on quantum logic spectroscopy on forbidden transitions in HCIs and subsequent low-energy searches for physics beyond the Standard Model.